iron nanoparticles thesis

Information

• Author Services

Initiatives

You are accessing a machine-readable page. In order to be human-readable, please install an RSS reader.

All articles published by MDPI are made immediately available worldwide under an open access license. No special permission is required to reuse all or part of the article published by MDPI, including figures and tables. For articles published under an open access Creative Common CC BY license, any part of the article may be reused without permission provided that the original article is clearly cited. For more information, please refer to https://www.mdpi.com/openaccess .

Feature papers represent the most advanced research with significant potential for high impact in the field. A Feature Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for future research directions and describes possible research applications.

Feature papers are submitted upon individual invitation or recommendation by the scientific editors and must receive positive feedback from the reviewers.

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

Original Submission Date Received: .

• Active Journals
• Find a Journal
• Proceedings Series
• For Authors
• For Reviewers
• For Editors
• For Librarians
• For Publishers
• For Societies
• For Conference Organizers
• Open Access Policy
• Institutional Open Access Program
• Special Issues Guidelines
• Editorial Process
• Research and Publication Ethics
• Article Processing Charges
• Testimonials
• Preprints.org
• SciProfiles
• Encyclopedia

Article Menu

• Subscribe SciFeed
• Recommended Articles
• PubMed/Medline
• Google Scholar
• on Google Scholar
• Table of Contents

Find support for a specific problem in the support section of our website.

Please let us know what you think of our products and services.

Visit our dedicated information section to learn more about MDPI.

JSmol Viewer

Green synthesis of iron nanoparticles and their environmental applications and implications.

Graphical Abstract

1. Introduction

2. green routes for the synthesis of metallic iron nanoparticles, 2.1. synthesis by biocompatible green reagents, 2.2. synthesis by microorganisms, 2.3. synthesis of iron nanoparticles from plant biomaterials, 2.4. other plant materials, 2.5. possible mechanism of nanoparticles synthesis, 3. environmental applications of green iron nanoparticles, 3.1. degradation of dyes, 3.2. removal of heavy metals, 3.3. wastewater treatment, 3.4. antibacterial activity, 3.5. stabilised/immobilised plant mediated fenps for degradation of pollutants, 4. environmental implications of iron nanoparticles, 5. conclusions and future perspective, acknowledgments, authors contribution, conflicts of interest, abbreviations.

• Christian, P.; Von der Kammer, F.; Baalousha, M.; Hofmann, T. Nanoparticles: Structure, properties, preparation and behaviour in environmental media. Ecotoxicology 2008 , 17 , 326–343. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Rotello, V.M. Nanoparticles: Building Blocks for Nanotechnology ; Springer Science & Business Media: New York, NY, USA, 2004. [ Google Scholar ]
• Virkutyte, J.; Varma, R.S. Chapter 2 Environmentally Friendly Preparation of Metal Nanoparticles. In Sustainable Preparation of Metal Nanoparticles: Methods and Applications ; The Royal Society of Chemistry: London, UK, 2013; pp. 7–33. [ Google Scholar ]
• Mandal, D.; Bolander, M.E.; Mukhopadhyay, D.; Sarkar, G.; Mukherjee, P. The use of microorganisms for the formation of metal nanoparticles and their application. Appl. Microbiol. Biotechnol. 2006 , 69 , 485–492. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Jebali, A.; Ramezani, F.; Kazemi, B. Biosynthesis of silver nanoparticles by Geotricum sp. J. Clust. Sci. 2011 , 22 , 225–232. [ Google Scholar ] [ CrossRef ]
• Lin, K.-S.; Chang, N.-B.; Chuang, T.-D. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater. Sci. Technol. Adv. Mater. 2008 , 9 , 025015. [ Google Scholar ] [ CrossRef ]
• Gui, M.; Smuleac, V.; Ormsbee, L.E.; Sedlak, D.L.; Bhattacharyya, D. Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water. J. Nanopart. Res. 2012 , 14 , 1–16. [ Google Scholar ] [ CrossRef ]
• He, F.; Zhao, D. Preparation and characterization of a new class of starch-stabilized bimetallic nanoparticles for degradation of chlorinated hydrocarbons in water. Environ. Sci. Technol. 2005 , 39 , 3314–3320. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Gao, S.; Shi, Y.; Zhang, S.; Jiang, K.; Yang, S.; Li, Z.; Takayama-Muromachi, E. Biopolymer-assisted green synthesis of iron oxide nanoparticles and their magnetic properties. J. Phys. Chem. C 2008 , 112 , 10398–10401. [ Google Scholar ] [ CrossRef ]
• Jegan, A.; Ramasubbu, A.; Saravanan, S.; Vasanthkumar, S. One-pot synthesis and characterization of biopolymer—Iron oxide nanocomposite. Int. J. Nano Dimens. 2011 , 2 , 105–110. [ Google Scholar ]
• Nadagouda, M.N.; Varma, R.S. A greener synthesis of core (Fe, Cu)-shell (Au, Pt, Pd, and Ag) nanocrystals using aqueous Vitamin C. Cryst. Growth Des. 2007 , 7 , 2582–2587. [ Google Scholar ] [ CrossRef ]
• Savasari, M.; Emadi, M.; Bahmanyar, M.A.; Biparva, P. Optimization of Cd(II) removal from aqueous solution by ascorbic acid-stabilized zero valent iron nanoparticles using response surface methodology. J. Ind. Eng. Chem. 2015 , 21 , 1403–1409. [ Google Scholar ] [ CrossRef ]
• Sreeja, V.; Jayaprabha, K.N.; Joy, P.A. Water-dispersible ascorbic-acid-coated magnetite nanoparticles for contrast enhancement in mri. Appl. Nanosci. 2014 , 5 , 435–441. [ Google Scholar ] [ CrossRef ]
• Krishna, R.; Titus, E.; Krishna, R.; Bardhan, N.; Bahadur, D.; Gracio, J. Wet-chemical green synthesis of l -lysine amino acid stabilized biocompatible iron-oxide magnetic nanoparticles. J. Nanosci. Nanotechnol. 2012 , 12 , 6645–6651. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Siskova, K.M.; Straska, J.; Krizek, M.; Tucek, J.; Machala, L.; Zboril, R. Formation of zero-valent iron nanoparticles mediated by amino acids. Procedia Environ. Sci. 2013 , 18 , 809–817. [ Google Scholar ] [ CrossRef ]
• Sayyad, A.S.; Balakrishnan, K.; Ci, L.; Kabbani, A.T.; Vajtai, R.; Ajayan, P.M. Synthesis of iron nanoparticles from hemoglobin and myoglobin. Nanotechnology 2012 , 23 , 055602. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Lu, W.; Shen, Y.; Xie, A.; Zhang, W. Green synthesis and characterization of superparamagnetic Fe 3 O 4 nanoparticles. J. Magn. Magn. Mater. 2010 , 322 , 1828–1833. [ Google Scholar ] [ CrossRef ]
• Sun, X.; Zheng, C.; Zhang, F.; Yang, Y.; Wu, G.; Yu, A.; Guan, N. Size-controlled synthesis of magnetite (Fe 3 O 4 ) nanoparticles coated with glucose and gluconic acid from a single Fe(III) precursor by a sucrose bifunctional hydrothermal method. J. Phys. Chem. C 2009 , 113 , 16002–16008. [ Google Scholar ] [ CrossRef ]
• Yan, Q.; Street, J.; Yu, F. Synthesis of carbon-encapsulated iron nanoparticles from wood derived sugars by hydrothermal carbonization (HTC) and their application to convert bio-syngas into liquid hydrocarbons. Biomass Bioenergy 2015 , 83 , 85–95. [ Google Scholar ] [ CrossRef ]
• Herrera-Becerra, R.; Rius, J.L.; Zorrilla, C. Tannin biosynthesis of iron oxide nanoparticles. Appl. Phys. A 2010 , 100 , 453–459. [ Google Scholar ] [ CrossRef ]
• Dorniani, D.; Hussein, M.Z.; Kura, A.U.; Fakurazi, S.; Shaari, A.H.; Ahmad, Z. Preparation of Fe 3 O 4 magnetic nanoparticles coated with gallic acid for drug delivery. Int. J. Nanomed. 2012 , 7 , 5745–5756. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Bharde, A.; Wani, A.; Shouche, Y.; Joy, P.A.; Prasad, B.L.V.; Sastry, M. Bacterial aerobic synthesis of nanocrystalline magnetite. J. Am. Chem. Soc. 2005 , 127 , 9326–9327. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Bharde, A.A.; Parikh, R.Y.; Baidakova, M.; Jouen, S.; Hannoyer, B.; Enoki, T.; Prasad, B.; Shouche, Y.S.; Ogale, S.; Sastry, M. Bacteria-mediated precursor-dependent biosynthesis of superparamagnetic iron oxide and iron sulfide nanoparticles. Langmuir 2008 , 24 , 5787–5794. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Moon, J.W.; Rawn, C.J.; Rondinone, A.J.; Love, L.J.; Roh, Y.; Everett, S.M.; Lauf, R.J.; Phelps, T.J. Large-scale production of magnetic nanoparticles using bacterial fermentation. J. Ind. Microbiol. Biotechnol. 2010 , 37 , 1023–1031. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Sundaram, P.A.; Augustine, R.; Kannan, M. Extracellular biosynthesis of iron oxide nanoparticles by Bacillus subtilis strains isolated from rhizosphere soil. Biotechnol. Bioprocess Eng. 2012 , 17 , 835–840. [ Google Scholar ] [ CrossRef ]
• Elcey, C.; Kuruvilla, A.T.; Thomas, D. Synthesis of magnetite nanoparticles from optimized iron reducing bacteria isolated from iron ore mining sites. Int. J. Curr. Microbiol. Appl. Sci. 2014 , 3 , 408–417. [ Google Scholar ]
• Bharde, A.; Rautaray, D.; Bansal, V.; Ahmad, A.; Sarkar, I.; Yusuf, S.M.; Sanyal, M.; Sastry, M. Extracellular biosynthesis of magnetite using fungi. Small 2006 , 2 , 135–141. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Kaul, R.K.; Kumar, P.; Burman, U.; Joshi, P.; Agrawal, A.; Raliya, R.; Tarafdar, J.C. Magnesium and iron nanoparticles production using microorganisms and various salts. Mater. Sci. Poland 2012 , 30 , 254–258. [ Google Scholar ] [ CrossRef ]
• Pavani, K.V.; Kumar, N.S. Adsorption of iron and synthesis of iron nanoparticles by Aspergillus species kvp 12. Am. J. Nanomater. 2013 , 1 , 24–26. [ Google Scholar ]
• Mohamed, Y.M.; Azzam, A.M.; Amin, B.H.; Safwat, N.A. Mycosynthesis of iron nanoparticles by Alternaria alternata and its antibacterial activity. Afr. J. Biotechnol. 2015 , 14 , 1234–1241. [ Google Scholar ] [ CrossRef ]
• Mahdavi, M.; Namvar, F.; Ahmad, M.B.; Mohamad, R. Green biosynthesis and characterization of magnetic iron oxide (Fe 3 O 4 ) nanoparticles using seaweed ( Sargassum muticum ) aqueous extract. Molecules 2013 , 18 , 5954–5964. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Subramaniyam, V.; Subashchandrabose, S.R.; Thavamani, P.; Megharaj, M.; Chen, Z.; Naidu, R. Chlorococcum sp. MM11—A novel phyco-nanofactory for the synthesis of iron nanoparticles. J. Appl. Phycol. 2015 , 27 , 1861–1869. [ Google Scholar ] [ CrossRef ]
• Dhillon, G.S.; Brar, S.K.; Kaur, S.; Verma, M. Green approach for nanoparticle biosynthesis by fungi: Current trends and applications. Crit. Rev. Biotechnol. 2012 , 32 , 49–73. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Kalaiarasi, R.; Jayallakshmi, N.; Venkatachalam, P. Phytosynthesis of nanoparticles and its applications. Plant Cell Biotechnol. Mol. Biol. 2010 , 11 , 1–16. [ Google Scholar ]
• Iravani, S. Green synthesis of metal nanoparticles using plants. Green Chem. 2011 , 13 , 2638–2650. [ Google Scholar ] [ CrossRef ]
• Mukunthan, K.S.; Balaji, S. Silver nanoparticles shoot up from the root of Daucus carrota (L.). Int. J. Green Nanotechnol. 2012 , 4 , 54–61. [ Google Scholar ] [ CrossRef ]
• Zambre, A.; Upendran, A.; Shukla, R.; Chanda, N.; Katti, K.K.; Cutler, C.; Kannan, R.; Katti, K.V. Chapter 6 Green Nanotechnology—A Sustainable Approach in the Nanorevolution. In Sustainable Preparation of Metal Nanoparticles: Methods and Applications ; The Royal Society of Chemistry: London, UK, 2013; pp. 144–156. [ Google Scholar ]
• Hoag, G.E.; Collins, J.B.; Holcomb, J.L.; Hoag, J.R.; Nadagouda, M.N.; Varma, R.S. Degradation of bromothymol blue by ‘greener’ nano-scale zero-valent iron synthesized using tea polyphenols. J. Mater. Chem. 2009 , 19 , 8671–8677. [ Google Scholar ] [ CrossRef ]
• Shahwan, T.; Abu Sirriah, S.; Nairat, M.; Boyacı, E.; Eroğlu, A.E.; Scott, T.B.; Hallam, K.R. Green synthesis of iron nanoparticles and their application as a fenton-like catalyst for the degradation of aqueous cationic and anionic dyes. Chem. Eng. J. 2011 , 172 , 258–266. [ Google Scholar ] [ CrossRef ]
• Markova, Z.; Novak, P.; Kaslik, J.; Plachtova, P.; Brazdova, M.; Jancula, D.; Siskova, K.M.; Machala, L.; Marsalek, B.; Zboril, R.; et al. Iron(II,III)—Polyphenol complex nanoparticles derived from green tea with remarkable ecotoxicological impact. ACS Sustain. Chem. Eng. 2014 , 2 , 1674–1680. [ Google Scholar ] [ CrossRef ]
• Nadagouda, M.N.; Castle, A.B.; Murdock, R.C.; Hussain, S.M.; Varma, R.S. In vitro biocompatibility of nanoscale zerovalent iron particles (nZVI) synthesized using tea polyphenols. Green Chem. 2010 , 12 , 114–122. [ Google Scholar ] [ CrossRef ]
• Machado, S.; Pinto, S.L.; Grosso, J.P.; Nouws, H.P.; Albergaria, J.T.; Delerue-Matos, C. Green production of zero-valent iron nanoparticles using tree leaf extracts. Sci. Total Environ. 2013 , 445–446 , 1–8. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Pattanayak, M.; Nayak, P.L. Green synthesis and characterization of zero valent iron nanoparticles from the leaf extract of Azadirachta indica (neem). World J. Nano Sci. Technol. 2013 , 2 , 6–9. [ Google Scholar ]
• Wang, Z. Iron complex nanoparticles synthesized by eucalyptus leaves. ACS Sustain. Chem. Eng. 2013 , 1 , 1551–1554. [ Google Scholar ] [ CrossRef ]
• Wang, Z.; Fang, C.; Megharaj, M. Characterization of iron-polyphenol nanoparticles synthesized by three plant extracts and their fenton oxidation of azo dye. ACS Sustain. Chem. Eng. 2014 , 2 , 1022–1025. [ Google Scholar ] [ CrossRef ]
• Luo, F.; Chen, Z.; Megharaj, M.; Naidu, R. Biomolecules in grape leaf extract involved in one-step synthesis of iron-based nanoparticles. RSC Adv. 2014 , 4 , 53467–53474. [ Google Scholar ] [ CrossRef ]
• Awwad, A.M.; Salem, N.M. A green and facile approach for synthesis of magnetite nanoparticles. Nanosci. Nanotechnol. 2012 , 2 , 208–213. [ Google Scholar ] [ CrossRef ]
• Pattanayak, M.; Nayak, P.L. Ecofriendly green synthesis of iron nanoparticles from various plants and spices extract. J. Plant Anim. Environ. Sci. 2013 , 3 , 68–76. [ Google Scholar ]
• Senthil, M.; Ramesh, C. Biogenic synthesis of Fe 3 O 4 nanoparticles using Tridax procumbens leaf extract and its antibacterial activity on Pseudomonas aeruginosa . Dig. J. Nanomater. Biostruct. 2012 , 7 , 1655–1660. [ Google Scholar ]
• Rao, A.; Bankar, A.; Kumar, A.R.; Gosavi, S.; Zinjarde, S. Removal of hexavalent chromium ions by Yarrowia lipolytica cells modified with phyto-inspired Fe 0 /Fe 3 O 4 nanoparticles. J. Contam. Hydrol. 2013 , 146 , 63–73. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Makarov, V.V.; Makarova, S.S.; Love, A.J.; Sinitsyna, O.V.; Dudnik, A.O.; Yaminsky, I.V.; Taliansky, M.E.; Kalinina, N.O. Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants. Langmuir 2014 , 30 , 5982–5988. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Prasad, A.S. Iron oxide nanoparticles synthesized by controlled bio-precipitation using leaf extract of garlic vine ( Mansoa alliacea ). Mater. Sci. Semicond. Process. 2016 , 53 , 79–83. [ Google Scholar ] [ CrossRef ]
• Mohan Kumar, K.; Mandal, B.K.; Siva Kumar, K.; Sreedhara Reddy, P.; Sreedhar, B. Biobased green method to synthesise palladium and iron nanoparticles using Terminalia chebula aqueous extract. Spectrochim. Acta A 2013 , 102 , 128–133. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Kumar, B.; Smita, K.; Cumbal, L.; Debut, A. Biogenic synthesis of iron oxide nanoparticles for 2-arylbenzimidazole fabrication. J. Saudi Chem. Soc. 2014 , 18 , 364–369. [ Google Scholar ] [ CrossRef ]
• Venkateswarlu, S.; Natesh Kumar, B.; Prasad, C.H.; Venkateswarlu, P.; Jyothi, N.V.V. Bio-inspired green synthesis of Fe 3 O 4 spherical magnetic nanoparticles using Syzygium cumini seed extract. Physica. B 2014 , 449 , 67–71. [ Google Scholar ] [ CrossRef ]
• Becerra, R.H.; Zorrilla, C.; Ascencio, J.A. Production of iron oxide nanoparticles by a biosynthesis method: An environmentally friendly route. J. Phys. Chem. 2007 , 111 , 16147–16153. [ Google Scholar ]
• Herrera-Becerra, R.; Zorrilla, C.; Rius, J.L.; Ascencio, J.A. Electron microscopy characterization of biosynthesized iron oxide nanoparticles. Appl. Phys. A 2008 , 91 , 241–246. [ Google Scholar ] [ CrossRef ]
• Njagi, E.C.; Huang, H.; Stafford, L.; Genuino, H.; Galindo, H.M.; Collins, J.B.; Hoag, G.E.; Suib, S.L. Biosynthesis of iron and silver nanoparticles at room temperature using aqueous Sorghum bran extracts. Langmuir 2011 , 27 , 264–271. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Venkateswarlu, S.; Rao, Y.S.; Balaji, T.; Prathima, B.; Jyothi, N.V.V. Biogenic synthesis of Fe 3 O 4 magnetic nanoparticles using plantain peel extract. Mater. Lett. 2013 , 100 , 241–244. [ Google Scholar ] [ CrossRef ]
• Ahmmad, B.; Leonard, K.; Shariful Islam, M.; Kurawaki, J.; Muruganandham, M.; Ohkubo, T.; Kuroda, Y. Green synthesis of mesoporous hematite (α-Fe 2 O 3 ) nanoparticles and their photocatalytic activity. Adv. Powder Technol. 2013 , 24 , 160–167. [ Google Scholar ] [ CrossRef ]
• Phumying, S.; Labuayai, S.; Thomas, C.; Amornkitbamrung, V.; Swatsitang, E.; Maensiri, S. Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe 3 O 4 ) nanoparticles. Appl. Phys. A 2012 , 111 , 1187–1193. [ Google Scholar ] [ CrossRef ]
• Huang, L.; Weng, X.; Chen, Z.; Megharaj, M.; Naidu, R. Synthesis of iron-based nanoparticles using Oolong tea extract for the degradation of malachite green. Spectrochim. Acta A 2013 , 117 , 801–804. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Wang, Z.; Fang, C.; Mallavarapu, M. Characterization of iron–polyphenol complex nanoparticles synthesized by sage ( Salvia officinalis ) leaves. Environ. Technol. Innov. 2015 , 4 , 92–97. [ Google Scholar ] [ CrossRef ]
• Kuang, Y.; Wang, Q.; Chen, Z.; Megharaj, M.; Naidu, R. Heterogeneous fenton-like oxidation of monochlorobenzene using green synthesis of iron nanoparticles. J. Colloid Interface Sci. 2013 , 410 , 67–73. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Huang, L.; Luo, F.; Chen, Z.; Megharaj, M.; Naidu, R. Green synthesized conditions impacting on the reactivity of Fe NPs for the degradation of malachite green. Spectrochim. Acta A 2015 , 137 , 154–159. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Madhavi, V.; Prasad, T.N.; Reddy, A.V.; Ravindra Reddy, B.; Madhavi, G. Application of phytogenic zerovalent iron nanoparticles in the adsorption of hexavalent chromium. Spectrochim. Acta A 2013 , 116 , 17–25. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Mystrioti, C.; Xenidis, A.; Papassiopi, N. Reduction of hexavalent chromium with polyphenol-coated nano zero-valent iron: Column studies. Desalination Water Treat. 2014 , 56 , 1162–1170. [ Google Scholar ] [ CrossRef ]
• Mystrioti, C.; Papassiopi, N.; Xenidis, A.; Dermatas, D.; Chrysochoou, M. Column study for the evaluation of the transport properties of polyphenol-coated nanoiron. J. Hazard. Mater. 2015 , 281 , 64–69. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Xiao, Z.; Yuan, M.; Yang, B.; Liu, Z.; Huang, J.; Sun, D. Plant-mediated synthesis of highly active iron nanoparticles for Cr(VI) removal: Investigation of the leading biomolecules. Chemosphere 2016 , 150 , 357–364. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Chrysochoou, M.; McGuirea, M.; Dahalb, G. Transport characteristics of green-tea nano-scale zero valent iron as a function of soil mineralogy. Chem. Eng. Trans. 2012 , 28 , 122–126. [ Google Scholar ]
• Wang, T.; Jin, X.; Chen, Z.; Megharaj, M.; Naidu, R. Green synthesis of Fe nanoparticles using Eucalyptus leaf extracts for treatment of eutrophic wastewater. Sci. Total Environ. 2014 , 466–467 , 210–213. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Wang, T.; Lin, J.; Chen, Z.; Megharaj, M.; Naidu, R. Green synthesized iron nanoparticles by green tea andeucalyptus leaves extracts used for removal of nitrate in aqueous solution. J. Clean. Prod. 2014 , 83 , 413–419. [ Google Scholar ] [ CrossRef ]
• Kiruba Daniel, S.C.G.; Vinothini, G.; Subramanian, N.; Nehru, K.; Sivakumar, M. Biosynthesis of Cu, ZVI, and Ag nanoparticles using Dodonaea viscosa extract for antibacterial activity against human pathogens. J. Nanopart. Res. 2012 , 15 , 1319. [ Google Scholar ] [ CrossRef ]
• Ponder, S.M.; Darab, J.G.; Mallouk, T.E. Remediation of Cr(VI) and Pb(II) aqueous solutions using supported, nanoscale zero-valent iron. Environ. Sci. Technol. 2000 , 34 , 2564–2569. [ Google Scholar ] [ CrossRef ]
• Hu, J.; Lo, I.; Chen, G. Removal of Cr(VI) by magnetite. Water Sci. Technol. 2004 , 50 , 139–146. [ Google Scholar ] [ PubMed ]
• Tang, S.C.; Lo, I.M. Magnetic nanoparticles: Essential factors for sustainable environmental applications. Water Res. 2013 , 47 , 2613–2632. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Suthersan, S.S.; Payne, F.C. In Situ Remediation Engineering ; Taylor & Francis: Oxfordshire, UK, 2004; p. 304. [ Google Scholar ]
• Smuleac, V.; Varma, R.; Sikdar, S.; Bhattacharyya, D. Green synthesis of Fe and Fe/Pd bimetallic nanoparticles in membranes for reductive degradation of chlorinated organics. J. Membr. Sci. 2011 , 379 , 131–137. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Tandon, P.K.; Shukla, R.C.; Singh, S.B. Removal of arsenic(III) from water with clay-supported zerovalent iron nanoparticles synthesized with the help of tea liquor. Ind. Eng. Chem. Res. 2013 , 52 , 10052–10058. [ Google Scholar ] [ CrossRef ]
• Prasad, K.S.; Gandhi, P.; Selvaraj, K. Synthesis of green nano iron particles (GnIP) and their application in adsorptive removal of As(III) and As(V) from aqueous solution. Appl. Surf. Sci. 2014 , 317 , 1052–1059. [ Google Scholar ] [ CrossRef ]
• Martínez-Cabanas, M.; López-García, M.; Barriada, J.L.; Herrero, R.; Sastre de Vicente, M.E. Green synthesis of iron oxide nanoparticles. Development of magnetic hybrid materials for efficient As(V) removal. Chem. Eng. J. 2016 , 301 , 83–91. [ Google Scholar ] [ CrossRef ]
• Vittori Antisari, L.; Carbone, S.; Gatti, A.; Vianello, G.; Nannipieri, P. Toxicity of metal oxide (CeO 2 , Fe 3 O 4 , SnO 2 ) engineered nanoparticles on soil microbial biomass and their distribution in soil. Soil Biol. Biochem. 2013 , 60 , 87–94. [ Google Scholar ] [ CrossRef ]
• Sacca, M.L.; Fajardo, C.; Costa, G.; Lobo, C.; Nande, M.; Martin, M. Integrating classical and molecular approaches to evaluate the impact of nanosized zero-valent iron (nZVI) on soil organisms. Chemosphere 2014 , 104 , 184–189. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Fajardo, C.; Sacca, M.L.; Martinez-Gomariz, M.; Costa, G.; Nande, M.; Martin, M. Transcriptional and proteomic stress responses of a soil bacterium Bacillus cereus to nanosized zero-valent iron (nZVI) particles. Chemosphere 2013 , 93 , 1077–1083. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Auffan, M.; Achouak, W.; Rose, J.; Roncato, M.-A.; Chanéac, C.; Waite, D.T.; Masion, A.; Woicik, J.C.; Wiesner, M.R.; Bottero, J.-Y. Relation between the redox state of iron-based nanoparticles and their cytotoxicity toward Escherichia coli . Environ. Sci. Technol. 2008 , 42 , 6730–6735. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Lee, C.; Kim, J.Y.; Lee, W.I.; Nelson, K.L.; Yoon, J.; Sedlak, D.L. Bactericidal effect of zero-valent iron nanoparticles on Escherichia coli . Environ. Sci. Technol. 2008 , 42 , 4927–4933. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Li, Z.; Greden, K.; Alvarez, P.J.J.; Gregory, K.B.; Lowry, G.V. Adsorbed polymer and NOM limits adhesion and toxicity of nano scale zerovalent iron to E. coli . Environ. Sci. Technol. 2010 , 44 , 3462–3467. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Phenrat, T.; Long, T.C.; Lowry, G.V.; Veronesi, B. Partial oxidation (“aging”) and surface modification decrease the toxicity of nanosized zerovalent iron. Environ. Sci. Technol. 2009 , 43 , 195–200. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Chen, P.J.; Wu, W.L.; Wu, K.C. The zerovalent iron nanoparticle causes higher developmental toxicity than its oxidation products in early life stages of Medaka fish. Water Res. 2013 , 47 , 3899–3909. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Baumann, J.; Koser, J.; Arndt, D.; Filser, J. The coating makes the difference: Acute effects of iron oxide nanoparticles on Daphnia magna . Sci. Total Environ. 2014 , 484 , 176–184. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Barhoumi, L.; Dewez, D. Toxicity of superparamagnetic iron oxide nanoparticles on green alga Chlorella vulgaris . BioMed Res. Int. 2013 , 2013 , 647974. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Li, H.; Zhou, Q.; Wu, Y.; Fu, J.; Wang, T.; Jiang, G. Effects of waterborne nano-iron on medaka ( Oryzias latipes ): Antioxidant enzymatic activity, lipid peroxidation and histopathology. Ecotoxicol. Environ. Saf. 2009 , 72 , 684–692. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Remya, A.S.; Ramesh, M.; Saravanan, M.; Poopal, R.K.; Bharathi, S.; Nataraj, D. Iron oxide nanoparticles to an indian major carp, Labeo rohita : Impacts on hematology, iono regulation and gill Na + /K + atpase activity. J. King Saud Univ. Sci. 2015 , 27 , 151–160. [ Google Scholar ] [ CrossRef ]
• Taze, C.; Panetas, I.; Kalogiannis, S.; Feidantsis, K.; Gallios, G.P.; Kastrinaki, G.; Konstandopoulos, A.G.; Vaclavikova, M.; Ivanicova, L.; Kaloyianni, M. Toxicity assessment and comparison between two types of iron oxide nanoparticles in Mytilus galloprovincialis . Aquat. Toxicol. 2016 , 172 , 9–20. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Blinova, I.; Kanarbik, L.; Irha, N.; Kahru, A. Ecotoxicity of nanosized magnetite to crustacean Daphnia magna and duckweed Lemna minor . Hydrobiologia 2015 . [ Google Scholar ] [ CrossRef ]
• He, S.; Feng, Y.; Ren, H.; Zhang, Y.; Gu, N.; Lin, X. The impact of iron oxide magnetic nanoparticles on the soil bacterial community. J. Soils Sediment. 2011 , 11 , 1408–1417. [ Google Scholar ] [ CrossRef ]
• El-Temsah, Y.S.; Joner, E.J. Ecotoxicological effects on earthworms of fresh and aged nano-sized zero-valent iron (nZVI) in soil. Chemosphere 2012 , 89 , 76–82. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Fajardo, C.; Gil-Diaz, M.; Costa, G.; Alonso, J.; Guerrero, A.M.; Nande, M.; Lobo, M.C.; Martin, M. Residual impact of aged nzvi on heavy metal-polluted soils. Sci. Total Environ. 2015 , 535 , 79–84. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Canivet, L.; Dubot, P.; Garcon, G.; Denayer, F.O. Effects of engineered iron nanoparticles on the bryophyte, Physcomitrella patens (hedw.) bruch & schimp, after foliar exposure. Ecotoxicol. Environ. Saf. 2015 , 113 , 499–505. [ Google Scholar ] [ PubMed ]
• El-Temsah, Y.S.; Joner, E.J. Impact of Fe and Ag nanoparticles on seed germination and differences in bioavailability during exposure in aqueous suspension and soil. Environ. Toxicol. 2012 , 27 , 42–49. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Shakibaie, M.; Shahverdi, A.R.; Faramarzi, M.A.; Hassanzadeh, G.R.; Rahimi, H.R.; Sabzevari, O. Acute and subacute toxicity of novel biogenic selenium nanoparticles in mice. Pharm. Biol. 2013 , 51 , 58–63. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Usha Rani, P.; Rajasekharreddy, P. Green synthesis of silver-protein (core-shell) nanoparticles using Piper betle L. Leaf extract and its ecotoxicological studies on daphnia magna. Colloids Surf. A 2011 , 389 , 188–194. [ Google Scholar ] [ CrossRef ]
• Filser, J.; Arndt, D.; Baumann, J.; Geppert, M.; Hackmann, S.; Luther, E.M.; Pade, C.; Prenzel, K.; Wigger, H.; Arning, J.; et al. Intrinsically green iron oxide nanoparticles? From synthesis via (eco-)toxicology to scenario modelling. Nanoscale 2013 , 5 , 1034–1046. [ Google Scholar ] [ CrossRef ] [ PubMed ]

Click here to enlarge figure

© 2016 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).

Share and Cite

Saif, S.; Tahir, A.; Chen, Y. Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications. Nanomaterials 2016 , 6 , 209. https://doi.org/10.3390/nano6110209

Saif S, Tahir A, Chen Y. Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications. Nanomaterials . 2016; 6(11):209. https://doi.org/10.3390/nano6110209

Saif, Sadia, Arifa Tahir, and Yongsheng Chen. 2016. "Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications" Nanomaterials 6, no. 11: 209. https://doi.org/10.3390/nano6110209

Article Metrics

Article access statistics, further information, mdpi initiatives, follow mdpi.

Subscribe to receive issue release notifications and newsletters from MDPI journals

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• Open access
• Published: 21 April 2021

One-pot green synthesis of iron oxide nanoparticles from Bauhinia tomentosa : Characterization and application towards synthesis of 1, 3 diolein

• Sushmitha Lakshminarayanan 2 ,
• M. Furhana Shereen 1 ,
• K. L. Niraimathi 2 ,
• P. Brindha 2 &
• A. Arumugam 1  

Scientific Reports volume  11 , Article number:  8643 ( 2021 ) Cite this article

14k Accesses

71 Citations

Metrics details

• Biomaterials
• Nanobiotechnology

An Author Correction to this article was published on 31 August 2021

This article has been updated

The green synthesis of NPs through plant extracts can be a modest, one-pot alternative synthesis to the conventional physical or chemical method. The prime focus of this study is to produce MNPs by the reducing effect of Bauhinia tomentosa leaf extract, and it was immobilized in porcine pancreatic lipase (PPL). Synthesized NPs were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy, UV–Vis Spectrometry, Thermogravimetry, and Differential Scanning Calorimeter (DSC), Zeta potential test, VSM, BET and Fourier Transform Infrared Spectroscopy (FTIR). The effect of process parameters was studied, about the efficiency of immobilization are enzyme stability, the extent of enzyme reusability, its separation from products, the activity of immobilized enzyme, recovery, and its loss. Finally, the immobilized lipase was used for the synthesis of 1,3-diolein using enzyme-mediated esterification of oleic acid and glycerol. Under optimized condition (reaction temp-55  \(^\circ \) C; molar ratio-2.5:1; pH-7) diolein yield was achieved to be 94%. Therefore, this work was further used for the industrial production of 1,3-diacylglycerol since a perfect enzyme-catalyzed process was observed.

Similar content being viewed by others

Facile synthesis of iron nanoparticles from Camellia Sinensis leaves catalysed for biodiesel synthesis from Azolla filiculoides

Palladium supported magnetic Fucus Vesiculosus extract as a natural and novel catalyst for the synthesis of N -alkyl-2-(4-methyl-1-oxoisoquinolin-2(1 H )-yl)-2-phenylacetamide derivatives

Immobilized lipase enzyme on green synthesized magnetic nanoparticles using Psidium guava leaves for dye degradation and antimicrobial activities

Introduction.

With integrated technology and science, the orientation of research from the subsisting microscopic theme towards the nanoscopic system is materializing with scientific relevance 1 . The large surface-to-volume ratio and high adsorption capacity have put nanoparticles under the good adsorbents category 2 . They are synthesized in the nanometer scale with a range of 1–100 nm 3 and shape, size, porosity, chemical composition, etc 4 are various factors they depend on. Medicine, electrical instrumentation, engineering, environment, buildings, biomedical and biological purposes, etc. are heterogeneous domain platforms where nanostructures have extensive applications. To date, innumerable metal and metal oxide nanoparticles are being chemically synthesized by various methods 5 , 6 . However, toxicity may be entangled in such methods paving the way for unsafe byproducts formation 7 , 8 . Therefore, for nanoparticle synthesis, a simple, environmentally friendly, and cost-effective tactic is being explored. Chief aspects that put green synthesis of NPs over chemical synthesis under the profitable category are being more economical, less labor-intensive, less toxicity, and greater stability nature 9 .

Magnetic nanoparticles that transpire to be promising practical support can trammel challenges faced by conventional NPs 10 . We can separate the magnetic NPs using a magnetic field, thereby improving their recovery, increasing the activity and stability, and also reducing steric hindrance 11 . An increase in particle stability reflects the correlation of green synthesized magnetic nanoparticles by availing the organic matter from various plant part extracts 12 , 13 . Also, it is a swift and reasonable method as the plant extracts containing secondary metabolites can act as both reducing and fixing agents.

Iron oxide is a transition metal oxide existing in about 16 forms, which include oxides, hydroxides, and oxide-hydroxide polymorphs, track recording unique physical and chemical properties 14 , 15 . This reveals the far-flung applications of iron oxide particles. Therefore, attempts for the synthesis of Iron oxide nanoparticles are in the forerun. Arularasu et al. 2018 studied the production of Fe 3 O 4 NPs using aqueous Kappaphycus alvarezii (red seaweed). The degradation of textile waste by catalytic activity was effective using NPs formed by a reduction reaction and also exhibited antibacterial activity 16 . Lakshmi Pravallika et al., 2019 synthesized iron oxide nanoparticles using ethanolic extract of Centella asiatica (CAIONPs) by reducing ferrous and ferric chlorides which were administered to Swiss albino mice with a dosage of 2000 mg/kg body weight. Nil effects of the NPs on various tissues were revealed by histopathological studies, indicating that green synthesized NPs were safe for use in biomedical and drug delivery systems 17 . In a similar study by Izadiyan et al., 2018, iron oxide nanoparticles were synthesized using Juglans regia green husk extract by co-precipitation method of FeCl 3 and FeCl 2 and the cytotoxicity tests were performed on mouse embryonic fibroblast cell lines and human colorectal adenocarcinoma cell lines by MTT assay which had no toxic effect on both normal and cancerous cell lines 12 . Khatami et al., 2019 synthesized super-paramagnetic iron oxide nanoparticles (SPIONs) produced using a zero-calorie stevia extract which acts as both reducing and stabilizing agents. The antioxidant effect studied by DPPH assay indicated the activity of produced NPs in the acceptable range 18 . Table 1 reports the comparative studies of the synthesis of iron oxide nanoparticles from various sources reported in the literature with the present work. Bauhinia tomentosa is a legume species in the Fabaceae family, rich in phytochemicals such as flavonoids, quinones, tannins, etc. act as stabilizing and reducing agents in NPs production. It plays a significant role in the formation, capping, and stabilization of Iron (II) oxide nanoparticles due to the presence of phytochemical and bioactive compounds. The process was demanding due to the presence of polyphenols and antioxidants which shield the NPs from oxidation and aggregation 19 .

In the case of 1,3 diolein, the enzymatic approach was employed due to environmental pleasantness, safety, and mild reaction condition with improved yield. Conventionally, diacylglycerol was used to reduce the accumulation of body fat. The green synthesis of nanoparticles for enzyme immobilization has benefits to instigate the enhancement of the greater surface area, lower diffusion limitation, particle mobility, thermal stability, storage capacity, modulation of catalytic activity, cost-effective, low toxicity, effective preparation, and availability, and high productivity in terms of binding efficiency with enzymes. In the present work, to maximize the diolein yield and to improve the operational stability of the enzyme, a new synthesis was employed 20 , 21 . This work emphasizes on green route for the synthesis of Fe 2 O 3 (Iron (III) oxide) nanoparticles produced from Bauhinia tomentosa leaf extract and to synthesize 1,3 diolein using immobilized PPL.

Materials and methods

The porcine pancreatic lipase (PPL) 5 (Type II, 100–500 U/mg protein using olive oil) was purchased from Sigma Aldrich Co. India. For enzyme activity analysis via the olive oil emulsion method, chemicals were obtained from Hi-Media Laboratories: dipotassium hydrogen Phosphate and Potassium dihydrogen phosphate (preparation of pH 7 buffer), gum arabic, pure olive oil, and Sodium hydroxide. Chromatographically pure monoolein and oleic acid were purchased from Sigma—Aldrich (Shanghai-china). Bradford reagent was prepared using Coomassie brilliant blue, ethanol, phosphoric acid (85% pure), and glycerol. Biosynthetic Iron (II) oxide nanoparticles were used as a support for immobilization which was prepared using leaf extract and 0.01 M FeCl 3 . The leaf from Bauhinia tomentosa plant was used in the present study complies with institutional, national, and international guidelines and legislation. Permission to take leaf samples were obtained.

Biosynthesis of Fe 2 O 3 nanoparticles

The aqueous extract of Bauhinia tomentosa leaves and 0.01 M FeCl 3 solution were combined to effectuate the synthesis of iron (II) oxide nanoparticles. The extract was prepared by soaking the leaves in distilled water for 24 h 22 . The freshly prepared 0.01 M FeCl 3 solution was added dropwise to the leaf extract in a 1:1 ratio with continuous stirring. The synthesis of nanoparticles was observed with a color change from orangish-brown solution to black precipitate. The solution was centrifuged at 4000 rpm for 15 min, followed by washing of pellet with distilled water thrice. The resultant pellet was air-dried in a hot air oven at 90ºC for 2 h to obtain black-colored, purified nanoparticles. The powder was then purified by washing with acetone 23 .

Lipase immobilization

Porcine pancreatic lipase (PPL) was immobilized on the synthesized Fe 2 O 3 nanoparticles separately by cross-linking. 25 mg of Fe 2 O 3 was dispersed in 25 mL of potassium phosphate buffer to a pH of 7 in two separate flasks. Precisely weighed lipase (25 mg) from both sources was added to the above mixture separately (equal concentration of enzyme and nanoparticles: 1 mg/mL). The reaction was set at 35ºC at 150 rpm for 24 h. Filtration was employed to separate the immobilized lipase. The percentage of immobilization and specific enzyme activity was also determined. The enzyme concentration was measured by Bradford assay 24 .

Diolein synthesis

The enzymatic esterification of oleic acid and glycerol was done with the support of immobilized PPL. The reaction was carried out in a 50 mL flask on a rotary shaker at 200 rpm 25 . To make up the reaction mixture, 1.5 mmol of oleic acid, 0.5 mmol glycerol, 10 mL of t-butanol, and an appropriate amount of immobilized lipase was added (15% (wt%) of the substrate). 4 Å molecular sieves were added into the reaction mixture to remove the water content. 50 µL of the sample was taken out from the reaction mixture and centrifuged to obtain the supernatant and analyzed by HPLC 26 . All the experiments were done in triplicates. Overall process layout for synthesis of iron oxide nanoparticles from Bauhinia tomentosa and 1, 3 diolein production was presented in the Fig.  1 .

Schematic diagram of synthesis of iron oxide nanoparticles from Bauhinia tomentosa and 1, 3 diolein production.

Analysis of the samples

According to 20 , 27 , external standards of 1-monoolein, 2-monoolein, 1,2-diolein, 1,3-diolein, and triolein were used to prepare 8 different concentrations of calibration solution. The results were examined by Shimadzu 20A HPLC along with an evaporative light scattering detector (ELSD). 2µL of sample and 1 mL of acetone was entirely mixed, out of which 20µL of the sample was injected in a chromatographic column—C18 column (5 µm, 250 mm × 4.6 mm) (Dikma technology, PLATISIL ODS, china). To analyze the reaction mixture, gradient elution with acetonitrile and dichloromethane was used under various reaction conditions mentioned (100/0,0–4 min; 90/10,12–25 min; 70/30, 25–30 min; 20/80, 35–45 min; 100/0, 55–60 min). The flow rate was maintained at 1.5 mL min \(^{ - 1}\) , Column temperature at −40 °C, drift pipe temperature at −70 °C, and nitrogen pressure was set at 320kpa. The reaction times of 2-monoolein, 1-monoolein, 1,3-diolein, 1,2-diolein and triolein were 3.753, 4.534, 23.128, 23.883 and 42.925 min respectively.

Results and discussion

Iron (II) oxide nanoparticles were synthesized using Bauhinia tomentosa leaf extract. Transformation in color was observed from an orangish-brown solution to a black precipitate. The nanoparticles were washed with water and acetone thrice and dried at 90 ºC in a hot air oven to achieve black-colored purified nanoparticles.

Ferric Chloride solution of 0.01 M concentration gets reduced to Ferric oxide and gets precipitated in the leaf extract. This reaction materializes in the company of oxidizing agents like Vitamin E 28 . Phytochemicals such as flavonoids, quinines, tannins, etc. act as stabilizing agents in nanoparticle production in the presence of a polar solvent, water. Phenols and terpenoids may play a significant role in the formation, capping, and stabilization of Iron (II) oxide nanoparticles 29 . Also, due to Surface Plasmon Resonance, a color change was observed. For measuring adsorption of material onto planar metal or the surface of metal NPs many standard tools are formed based on SPR 30 .

Characterization of Fe 2 O 3 nanoparticles

Uv–vis spectrometry.

UV–Vis Spectrometry has revealed the characteristic formation of nanoparticles during color change based on the absorption spectra. A scanning wavelength measurement from 300 to 900 nm was executed to reveal a peak value at 328 nm which indicated the formation of nanoparticles (Fig.  2 ). A characteristic peak at 328 nm confirmed the formation of Fe 2 O 3 Nanoparticles 31 .

UV-V is Spectroscopy of Fe 2 O 3 Nanoparticles synthesized from Bauhinia tomentosa leaf extract using the FeCl 3 solution. The characteristic peak formed at 328 nm shows the formation of nanoparticles.

Fourier transform infrared spectroscopy

FTIR is ascribed to functional groups (=C–H, C=O, N–O, C–O, C–N) present in the compound (Fig.  3 ). FTIR spectroscopic studies confirm the presence of amides, phenols, nitrogen, and aromatic compounds that has a strong binding affinity with Fe and thus play a significant role in reducing and capping ferrous ions 32 . The spectrum reveals characteristic peaks at 3385.9 cm −1 stretching to O–H, 1624.7 cm −1 stretching to N=O, 1172.4 cm −1 and 1055.6 cm −1 stretching to O–C, 810.8 cm −1 and 555.7 cm −1 stretching to Fe–O stretches of Fe 2 O 3 7 . The synthesis of Fe 2 O 3 nanoparticles extracted from Bauhinia tomentosa aqueous leaf extract has been evinced by these chemical groups.

FT-IR Spectrum of bare Fe 2 O 3 Nanoparticles and lipase immobilized nanoparticles.

The stretching of carbonyl groups in lipase was observed by a broadening of peaks in the range of 3345 cm −1 –3650 cm −1 for both forms of the immobilized formulation. The amplitude of peaks at 3483, 2922, 1652, and 650 cm −1 increased dramatically, suggesting that lipase was effectively immobilized 33 . The peak strength of covalently immobilized lipase, on the other hand, decreased (Figure. 3 ), indicating that the enzyme-nano relationship was stable. Because of the pairing of NH-bending with CN stretching, the band based at 1541 cm −1 was credited to the amide II of enzymes.

Thermogravimetry and differential scanning calorimeter

Mass changes of a sample as a function of temperature in scanning mode are examined by TGA (dynamic TGA) (Fig.  4 ). The physical and chemical properties of materials, as a function of increasing temperature, can be determined. This decomposition/degradation temperature bear witness to mass changes in the materials. The approximate temperature of Fe 2 O 3 s transition of interest was found to be around 930  \(^\circ \) C. Characterization of coatings on NPs by evolved gas analysis can be achieved using TG-DSC techniques. DSC was grounded on the differences in the amount of heat required to increase the temperature of the sample. In combination with TGA, it was applied to study melting point, gas transitions, and exothermic decompositions. The graph depicts that the decomposition melting of the sample starts at around 250  \(^\circ \) C and ends at about 700  \(^\circ \) C revealing that the sample was Iron (II) oxide 34 . At a temperature of around 180 °C, the TGA curve showed a weight loss of around 3.0446 percent in the study. This weight loss may be attributed to the removal of water molecules removed by nanoparticles from the atmosphere, during which the sample weight is almost stable, indicating the sample's thermal stability.

DSC-TGA for Fe 2 O 3 nanoparticles synthesized from Bauhinia tomentosa leaf extract using FeCl 3 solution.

Zeta potential and field emission-scanning electron microscopy

Size is an important factor to define NPs although considerable debate exists on the size threshold to distinguish NPs from bulk materials. The particles were dispersed in water with a dielectric constant of 78.5, a refractive index of 1.33, and a viscosity of 0.887 cP 35 . A potential of −16 mV was found which was a good manifestation for nanoparticle formation. The potential difference between the EDL (electric double layer) of electrophoretically mobile particles and the layer of dispersant around them at the slipping plane is reflected by the zeta potential (Fig.  5 A). It is also termed electrokinetic potential, the potential at the slipping/shear plane of a colloid particle moving under the electric field. Therefore, the particle size distribution and magnitude of electric charge at the particle surface are determined 36 . Also, a zeta sizer was employed to determine the size of the particles. The size distribution was scanned by intensity (Fig.  5 B). However, due to differences in dispersion co-efficient and cluster formation, it did not provide accurate results. The FE-SEM image revealed the size of the synthesized nanoparticles (Fig.  6 ). Thus, eminently meticulous results were provided by FE-SEM. The average size was observed to be around 70 nm which is acceptable.

( A ) Zeta Potential for Fe 2 O 3 synthesized nanoparticles. From the graphical result, the potential was found to be −16 mV which was a good indication for the formation of nanoparticles. ( B ) Zeta sizer for Fe 2 O 3 synthesized nanoparticles from Bauhinia tomentosa leaf extract.

Scanning electron microscope (SEM) image of synthesized Fe 2 O 3 nanoparticle.

X-ray diffraction

X-Ray Diffraction (XRD) was performed to understand the crystalline structure of the nanoparticles. The sample consisting of fine grains of crystalline material to be studied was usually in powdered form 37 (Fig.  7 ). At a theta scale value of 27.4, the peak intensity was found to be the highest. The intensity count and percent intensity were found to be 169 and 100%, respectively. The JCPDS file 019–0629 closely matched with the XRD pattern observed in this study showing the characteristic peaks at 2θ of 21.6, 25.77, 31.06, 40.68, 45.45, 53.49, 56.44, and 61.11 corresponding to the face-centered cubic phase of (211), (220), (202), (213), (431), (512), (150) and (613) planes, respectively. The presence of strong and sharp peaks of Fe 2 O 3 crystals is attributed to the highly crystalline nature. The characteristic peaks at 2θ of 70.91 correspond to the crystal planes of (620) of crystalline Fe 3 O 4 -NPs, respectively. Material match analysis revealed the presence of Fe 2 O 3 at higher amounts in the sample with trace amounts of Fe 3 O 4 . This indicated the formation of Iron (II) oxide.

X-ray diffraction (XRD) pattern for synthesized iron oxide (Fe 2 O 3 ) nanoparticle. The figure illustrated that the peak intensity was found to be highest at a theta scale value of 27.4.

Brunauer–Emmett–Teller (BET) surface area analysis

N 2 adsorption/desorption isotherms at liquid nitrogen temperature were used to determine the precise surface area (Brunauer–Emmett–Teller, BET) pore size and pore volume of the samples. Figure  8 displays the outcomes of the BET analysis 38 . The synthesized iron oxide nanoparticles display TYPE IV adsorption–desorption isotherm. The prepared nanoparticles showed Brunauer–Emmett–Teller (BET) surface area, pore-volume, and diameter were calculated to be 48.8 m 2 /g with 0.096 cm 3 /g and 7.9 nm respectively. From the adsorption–desorption isotherm, it can be noticed that around 62.04 cm 3 /g of nitrogen was adsorbed at maximum relative pressure (P/P 0 ) of 1 39 . The hysteresis pattern shows that the condensation occurred approximately from 0.4 to 0.9 (P/P 0 ) (Fig.  8 ). These findings suggest that these particles have a large surface area and are nanometer in size. In contrast to the other samples, the iron oxide Np sample had the highest surface area and had a very small particle size along with a strong adsorption property, according to the BET report 40 .

N 2 adsorption–desorption graph with a variation of pore diameter with respect to dV/dlog(D).

Vibrating sample magnetometer (VSM) analysis

A vibrating sample magnetometer was used to test the magnetic properties of the iron oxide nanoparticles, at room temperature, the hysteresis loops of the bare Fe 3 O 4 and iron coated NPs are shown in Fig.  9 41 . As the magnetic field is withdrawn from both prepared NPs, the magnetization decreases from a plateau state to zero. This action clearly shows superparamagnetic behavior 42 . The bare Fe 3 O 4 and nanoparticles have a saturation magnetization (Ms) of 87.8 emu/g and coercivity (Ce) of 4.09 Oe, suggesting that they have strong magnetic properties. Similarly, iron-oxide nanoparticles show (Ms) of 55.83 emu/g and (Ce) of 1.02 Oe. It can also be categorized as a soft magnet material category due to its low coercivity value. These findings indicate that our synthesized nanoparticles exhibit a suitable behavior and can be used for enzyme immobilization and ease of recovery after the completion of the reaction.

VSM curves for the prepared iron oxide nanoparticle and bare Fe 3 O 4 .

Determination of enzyme activity

The percentage immobilization of PPL on iron-oxide nanoparticles was found to be 70.1%. The enzyme activity of PPL covalently immobilized on the Fe 2 O 3 matrix was calculated to be 266 U/mL 43 . Either by covalent bonding or adsorption, the interaction of enzymes with the NPs surface provides the inkling of the operational stability of enzymes 24 . However, a conclusion has been derived by the higher enzyme activity of PPL immobilized on Fe 2 O 3 nanoparticles that this matrix could be more competitive compared to other matrices. The catalyst turnover number (TON) and the turnover frequency (TOF) for the immobilized enzyme on iron (II) oxide nanoparticles for the synthesis of 1, 3 diolein are 1.17 mol/g and 0.0039 mol/g.min.

Effect of various reaction parameters

Finding the effect of various parameters that affect the diolein yield based on reaction time, temperature, substrate molar ratio, and reusability of the immobilized enzyme has been pivoted in this study (Fig.  10 ). An indispensable role is played by the reaction temperature in biocatalysts. Higher temperature results in the deactivation of the enzyme. This work entails five different temperatures (40, 45, 50, 55, 60, and 65 °C) and was ascertained to observe the diolein yield. At 55  \(^\circ \) C, diolein yield reaches the highest value of 92.5%. More than that range, the yield and initial reaction rate of diolein get decreased and simultaneously acyl migration will take place which results in triolein formation and diolein yield reaches optimum value after 7 h of reaction time.

Effect of process parameters for the conversion of 1,3-diolein synthesis via esterification of oleic acid with monoolein catalyzed by immobilized Porcine pancreatic lipase. ( A ) The time course percentage conversion. ( B ) Temperature. ( C ) Substrate molar ratio. ( D ) Reusability studies.

To investigate the optimum level of the substrate molar ratio based on the yield of 1,3 diolein, different ranges were taken to experiment (2:1, 2.5:1, 3:1, 3.5:1, and 4:1). The diolein yield will not be tremendously affected by an escalation in the molar ratio of oleic acid to glycerol. But higher concentrations of oleic acid will simultaneously diminish the yield of 1,3 diolein formation. Therefore, based on molar ratios, no significant difference was observed in the diolein yield. And from this work, it was observed that the substrate molar ratio of oleic acid to glycerol (2.5:1) shows the highest yield of diolein as 94%. Cost efficiency is imperatively influenced by the reusability of the immobilized enzyme 44 . The operational stability of immobilized lipase was carried out under optimized conditions. From the results, it was observed that 90% of the original activity was maintained until 10 cycles and in this case, a maximum yield of 1,3 diolein was achieved 45 . Therefore, the catalytic activity of the enzyme was not lost, and also it was proved how effectively the enzyme binds to the matrix. From the above results, it was clearly shown that Fe 2 O 3 nanoparticles were an eminent matrix for lipase (PPL) immobilization. Therefore, the immobilization of enzymes on a solid support such as nanoparticles is more advantageous due to improved stability, enhanced thermal efficiency and pH, increased enzyme loading, and reusability with simple handling and separation making the process feasible with maximal yield. Table 2 represents the detailed comparison studies reported in the literature for the synthesis of 1,3 diolein using lipase catalysis with the present work. It was found that a higher yield of 1,3 diolein was obtained with the lipase immobilization on the iron oxide nanoparticles and also the immobilized enzyme eases the process of recovery and reuse. This reduces the overall production cost of the 1,3 diolein synthesis.

This work highlighted the green synthesis of Fe 2 O 3 nanoparticles from Bauhinia tomentosa leaf extract and it was efficaciously implemented for lipase immobilization. Moreover, it was the pragmatic approach for enhancing the synthesis of 1,3-diolein by the esterification of oleic acid and glycerol. The phenolic compounds present in Bauhinia leaf extract play a vital role in boosting up the stability of Fe 2 O 3 nanoparticles. The distinct characteristics, size, and shape of Fe 2 O 3 nanoparticles were identified using FTIR and SEM analysis. XRD, TGA, and UV–Vis spectroscopic techniques were used to recognize the crystallographic structure, thermal stability, and optical behavior of the green synthesized nanoparticles were studied. Further, due to the high stability, effectiveness, enzyme activity, greater safety, low energy consumption, and high product quality of the immobilized lipase, it was employed for 1,3-diolein synthesis which will gain momentum for various applications. Finally, this greener optimistic work will aid in the large-scale synthesis of 1,3 diolein using the effective binding of immobilized lipase.

Data availability

The datasets used during the current study are available from the corresponding author on reasonable request.

Change history

31 august 2021.

A Correction to this paper has been published: https://doi.org/10.1038/s41598-021-97276-6

Ahghari, M. R., Soltaninejad, V. & Maleki, A. Author Correction: Synthesis of nickel nanoparticles by a green and convenient method as a magnetic mirror with antibacterial activities. Sci. Rep. 10 , 1–10. https://doi.org/10.1038/s41598-020-69679-4 (2020).

Article   CAS   Google Scholar  

Hua, M. et al. Heavy metal removal from water/wastewater by nanosized metal oxides: a review. J. Hazard. Mater. 212 , 317–331 (2012).

Karthik, K., Dhanuskodi, S., Gobinath, C. & Prabukumar, S. Multifunctional properties of CdO nanostructures synthesised through microwave assisted hydrothermal method multifunctional properties of CdO nanostructures Synthesised through microwave assisted hydrothermal method. Mater. Res. Innov. 8917 , 1–8 (2018).

Google Scholar  

Mahmoudi, H., Beitollahi, H., Tajik, S. & Jahani, S. Voltammetric determination of droxidopa in the presence of carbidopa using a nanostructured base electrochemical sensor. Russ. J. Electrochem. 53 , 452–460 (2017).

Article   Google Scholar  

Manjunatha, M., Kumar, R., Sahoo, B., Damle, R. & Ramesh, K. P. Determination of magnetic domain state of carbon coated iron nanoparticles via 57Fe zero-external-field NMR. J. Magn. Magn. Mater. https://doi.org/10.1016/j.jmmm.2018.01.017 (2018).

Miri, A., Darroudi, M., Entezari, R. & Sarani, M. Biosynthesis of gold nanoparticles using Prosopis farcta extract and its in vitro toxicity on colon cancer cells. Res. Chem. Intermed. https://doi.org/10.1007/s11164-018-3299-y (2018).

Lassoued, A., Dkhil, B., Gadri, A. & Ammar, S. Control of the shape and size of iron oxide (α-Fe2O3) nanoparticles synthesized through the chemical precipitation method. Results Phys. 7 , 3007–3015 (2017).

Article   ADS   Google Scholar  

Kayani, Z. N., Arshad, S., Riaz, S. & Naseem, S. Synthesis of iron oxide nanoparticles by sol&-gel technique and their characterization. IEEE Trans. Magn. 50 , 2200404/1-2200404/4 (2014).

Singh, A. et al. Green synthesis of metallic nanoparticles as effective alternatives to treat antibiotics resistant bacterial infections: A review. Biotechnol. Rep. 25 , e00427 (2020).

Rossi, L. M., Costa, N. J. S., Silva, F. P. & Wojcieszak, R. Magnetic nanomaterials in catalysis: advanced catalysts for magnetic separation and beyond. Green Chem. 16 , 2906–2933 (2014).

Kazemnejadi, M. et al. Fe 3 O 4 @SiO 2 @Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime. J. Mol. Struct. 1186 , 230–249 (2019).

Article   ADS   CAS   Google Scholar  

Izadiyan, Z. et al. Cytotoxicity assay of plant-mediated synthesized iron oxide nanoparticles using Juglans regia green husk extract. Arab. J. Chem. https://doi.org/10.1016/j.arabjc.2018.02.019 (2018).

Bharathi, D., Diviya Josebin, M., Vasantharaj, S. & Bhuvaneshwari, V. Biosynthesis of silver nanoparticles using stem bark extracts of Diospyros montana and their antioxidant and antibacterial activities. J. Nanostruct. Chem. 8 , 83–92 (2018).

Maleki, A., Hajizadeh, Z. & Salehi, P. Mesoporous halloysite nanotubes modified by CuFe 2 O 4 spinel ferrite nanoparticles and study of its application as a novel and efficient heterogeneous catalyst in the synthesis of pyrazolopyridine derivatives. Sci. Rep. 9 , 1–8 (2019).

Karpagavinayagam, P. & Vedhi, C. Green synthesis of iron oxide nanoparticles using Avicennia marina flower extract. Vacuum 160 , 286–292 (2019).

Arularasu, M. V., Devakumar, J. & Rajendran, T. V. An innovative approach for green synthesis of iron oxide nanoparticles: Characterization and its photocatalytic activity. Polyhedron 156 , 279–290 (2018).

Lakshmi Pravallika, P., Krishna Mohan, G., Venkateswara Rao, K. & Shanker, K. Biosynthesis, characterization and acute oral toxicity studies of synthesized iron oxide nanoparticles using ethanolic extract of Centella asiatica plant. Mater. Lett. 236 , 256–259 (2019).

Khatami, M. et al. Super-paramagnetic iron oxide nanoparticles (SPIONs): Greener synthesis using Stevia plant and evaluation of its antioxidant properties. J. Clean. Prod. 208 , 1171–1177 (2019).

Farshchi, H. K., Azizi, M., Jaafari, M. R., Nemati, S. H. & Fotovat, A. Green synthesis of iron nanoparticles by Rosemary extract and cytotoxicity effect evaluation on cancer cell lines. Biocatal. Agric. Biotechnol. 16 , 54–62 (2018).

Duan, Z. Q., Du, W. & Liu, D. H. Improved synthesis of 1,3-diolein by Novozym 435-mediated esterification of monoolein with oleic acid. J. Mol. Catal. B Enzym. 89 , 1–5 (2013).

Wang, X. et al. Preparation of 1,3-diolein by irreversible acylation. JAOCS J. Am. Oil Chem. Soc. 92 , 185–191 (2015).

Sharmila, G. et al. Biosynthesis, characterization, and antibacterial activity of zinc oxide nanoparticles derived from Bauhinia tomentosa leaf extract. J. Nanostructure Chem. 8 , 293–299 (2018).

Othman, A. M., Elsayed, M. A., Al-Balakocy, N. G., Hassan, M. M. & Elshafei, A. M. Correction to: Biosynthesis and characterization of silver nanoparticles induced by fungal proteins and its application in different biological activities. J. Genet. Eng. Biotechnol. 18 , 1–13. https://doi.org/10.1186/s43141-019-0008-1 (2020).

Arumugam, A., Jegadeesan, G. B. & Ponnusami, V. Comparative studies on catalytic properties of immobilized lipase on low-cost support matrix for transesterification of pinnai oil. Biomass Convers. Biorefinery 8 , 1 (2018).

Yesiloglu, Y. & Kilic, I. Lipase-Catalyzed Esterification of Glycerol and Oleic Acid. JAOCS . J. Am. Oil Chem. Soc. 81 , 281–284 (2004).

Maleki, A. One-pot multicomponent synthesis of diazepine derivatives using terminal alkynes in the presence of silica-supported superparamagnetic iron oxide nanoparticles. Tetrahedron Lett. 54 , 2055–2059 (2013).

Duan, Z. Q., Du, W. & Liu, D. H. Rational synthesis of 1,3-diolein by enzymatic esterification. J. Biotechnol. 159 , 44–49 (2012).

Article   CAS   PubMed   Google Scholar  

Beach, R. United States Patent (19). (1975).

Singh, J. et al. ‘Green’ synthesis of metals and their oxide nanoparticles: applications for environmental remediation. J. Nanobiotechnol. 16 , 1–24 (2018).

Jana, J., Ganguly, M. & Pal, T. Enlightening surface plasmon resonance effect of metal nanoparticles for practical spectroscopic application. RSC Adv. 6 , 86174–86211 (2016).

Rufus, A., Sreeju, N. & Philip, D. Synthesis of biogenic hematite (α-Fe2O3) nanoparticles for antibacterial and nanofluid applications. RSC Adv. 6 , 94206–94217 (2016).

Hayyan, M., Hashim, M. A. & Alnashef, I. M. Superoxide ion: generation and chemical implications. Chem. Rev. 116 , 3029–3085 (2016).

Asmat, S., Husain, Q. & Khan, M. S. A polypyrrole-methyl anthranilate functionalized worm-like titanium dioxide nanocomposite as an innovative tool for immobilization of lipase: Preparation, activity, stability and molecular docking investigations. New J. Chem. 42 , 91–102 (2018).

Sharma, A. K., Pawar, C. A., Prasad, N. R., Yewale, M. A. & Kamble, D. B. Antimicrobial efficacy of green synthesized iron oxide nanoparticles (2018).

Thanh, N. T. K., Maclean, N. & Mahiddine, S. Mechanisms of nucleation and growth of nanoparticles in solution. Chem. Rev. 114 , 7610–7630 (2014).

Lowry, G. V. et al. Guidance to improve the scientific value of zeta-potential measurements in nanoEHS. Environ. Sci. Nano 3 , 953–965 (2016).

Predescu, A. M. et al. Synthesis and characterization of dextran-coated iron oxide nanoparticles. R. Soc. Open Sci. 5 , 1 (2018).

Paredes-García, V. et al. One pot Solvothermal synthesis of organic acid coated magnetic iron oxide Nanoparticles. J. Chil. Chem. Soc. 58 , 2011–2015 (2013).

Ansari, S. A. M. K. et al. Magnetic iron oxide nanoparticles: Synthesis, characterization and functionalization for biomedical applications in the Central Nervous System. Materials (Basel) 12 , 1 (2019).

Pershina, A. G. et al. Supporting data and methods for the characterization of iron oxide nanoparticles conjugated with pH-(low)-insertion peptide, testing their cytotoxicity and analyses of biodistribution in SCID mice bearing MDA-MB231 tumor. Data Br. 29 , 105062 (2020).

Patwa, R., Zandraa, O., Capáková, Z., Saha, N. & Sáha, P. Effect of iron-oxide nanoparticles impregnated bacterial cellulose on overall properties of alginate/casein hydrogels: Potential injectable biomaterial for wound healing applications. Polymers (Basel). 12 , 1–21 (2020).

El-Boubbou, K. et al. Preparation of iron oxide mesoporous magnetic microparticles as novel multidrug carriers for synergistic anticancer therapy and deep tumor penetration. Sci. Rep. 9 , 1–20 (2019).

Arumugam, A., Thulasidharan, D. & Jegadeesan, G. B. Process optimization of biodiesel production from Hevea brasiliensis oil using lipase immobilized on spherical silica aerogel. Renew. Energy 116 , 1 (2018).

Maleki, A. & Firouzi-Haji, R. L-Proline functionalized magnetic nanoparticles: a novel magnetically reusable nanocatalyst for one-pot synthesis of 2,4,6-triarylpyridines. Sci. Rep. 8 , 1–8 (2018).

Arumugam, A., Karuppasamy, G. & Jegadeesan, G. B. Synthesis of mesoporous materials from bamboo leaf ash and catalytic properties of immobilized lipase for hydrolysis of rubber seed oil. Mater. Lett. 225 , 113–116 (2018).

Dai, L., Liu, D., Liu, H. & Du, W. Kinetics and Mechanism of Solvent In fl uence on the Lipase- Catalyzed 1, 3-Diolein Synthesis. (2020).

Bi, Y. et al. Evaluation of the Candida sp. 99–125 lipase positional selectivity for 1,3-diolein synthesis. Biomed. Res. Int. 2019 , 1 (2019).

Zhao, J. F., Lin, J. P., Yang, L. R. & Wu, M. B. Preparation of high-purity 1, 3-diacylglycerol using performance-enhanced lipase immobilized on nanosized magnetite particles. Biotechnol. Bioprocess Eng. 24 (2), 326–336 (2019).

Duan, Z. Q., Fang, X. L., Wang, Z. Y., Bi, Y. H. & Sun, H. Sustainable process for 1,3-diolein synthesis catalyzed by immobilized lipase from penicillium expansum. ACS Sustain. Chem. Eng. 3 , 2804–2808 (2015).

Wang, Z., Du, W., Dai, L. & Liu, D. Study on Lipozyme TL IM-catalyzed esterification of oleic acid and glycerol for 1,3-diolein preparation. J. Mol. Catal. B Enzym. 127 , 11–17 (2016).

Duan, Z. Q., Du, W. & Liu, D. H. The mechanism of solvent effect on the positional selectivity of Candida antarctica lipase B during 1,3-diolein synthesis by esterification. Bioresour. Technol. 102 , 11048–11050 (2011).

Duan, Z. Q., Du, W. & Liu, D. H. The pronounced effect of water activity on the positional selectivity of Novozym 435 during 1,3-diolein synthesis by esterification. Catal. Commun. 11 , 356–358 (2010).

Duan, Z. Q., Du, W. & Liu, D. H. The solvent influence on the positional selectivity of Novozym 435 during 1,3-diolein synthesis by esterication. Bioresour. Technol. 101 , 2568–2571 (2010).

Rosu, R., Yasui, M., Iwasaki, Y. & Yamane, T. Enzymatic synthesis of symmetrical 1,3-diacylglycerols by direct esterification of glycerol in solvent-free system. JAOCS J. Am. Oil Chem. Soc. 76 , 839–843 (1999).

Sigurdardóttir, S. B. et al. Enzyme Immobilization on Inorganic Surfaces for Membrane Reactor Applications: Mass Transfer Challenges, Enzyme Leakage and Reuse of Materials. Advanced Synthesis & Catalysis 360 (14), 2578–2607 (2018).

Poorakbar, E. et al. Synthesis of magnetic gold mesoporous silica nanoparticles core shell for cellulase enzyme immobilization: Improvement of enzymatic activity and thermal stability. Process Biochemistry 71 , 92–100 (2018).

Park, H. J., Driscoll, A. J. & Johnson, P. A. The development and evaluation of β-glucosidase immobilized magnetic nanoparticles as recoverable biocatalysts. Biochemical Engineering Journal 133 , 66–73 (2018).

Saranya, S., Vijayarani, K. & Pavithra, S. Green Synthesis of Iron Nanoparticles using Aqueous Extract of Musa ornata Flower Sheath against Pathogenic Bacteria. Indian Journal of Pharmaceutical Sciences 79 (5), (2017).

S. Kanagasubbulakshmi, & Kadirvelu, K. Green synthesis of Iron oxide nanoparticles using Lagenaria siceraria and evaluation of its Antimicrobial activity. Defence Life Science Journal 2 (4), 422 (2017).

Park, H. J., McConnell, J. T., Boddohi, S., Kipper, M. J. & Johnson, P. A. Synthesis and characterization of enzyme–magnetic nanoparticle complexes: effect of size on activity and recovery. Colloids and Surfaces B: Biointerfaces 83 (2), 198–203 (2011).

Hoag, G. E. et al. Degradation of bromothymol blue by ‘greener’ nano-scale zero-valent iron synthesized using tea polyphenols. Journal of Materials Chemistry 19 (45), 8671 (2009).

Download references

Acknowledgements

The authors gratefully acknowledge the financial support provided by SERB (Science & Engineering Research Board), INDIA (Grant No. ECR/2017/001038/2017-20) to carry out the esterification process involved in the research work.

All of the sources of funding for the work described in this publication are acknowledged below: We acknowledge the financial support provided by the Research board, INDIA (Grant No. ECR/2017/001038/2017–20—SERB) in accompanying us to complete the work.

Author information

Authors and affiliations.

Bioprocess Intensification Laboratory, Centre for Bioenergy, School of Chemical and Biotechnology, SASTRA Deemed To Be University, Thirumalaisamudram, Thanjavur, 613401, India

M. Furhana Shereen & A. Arumugam

Centre for Advanced Research in Indian System of Medicine (CARISM), SASTRA Deemed University, Thirumalaisamudram, Thanjavur, 613401, India

Sushmitha Lakshminarayanan, K. L. Niraimathi & P. Brindha

You can also search for this author in PubMed   Google Scholar

Contributions

S.L. Collected the data; Wrote the paper F.M; Contributed data or analysis tools; Performed the analysis N.K.L; Conceived and designed the analysis; Contributed data or analysis tools B.P.; Conceived and designed the analysis; Contributed data or analysis tools A.A.; Conceived and designed the analysis; Contributed data or analysis tools; Performed the analysis; Wrote the paper. We confirm that the manuscript has been read and approved by all named authors. We confirm that the order of authors listed in the manuscript has been approved by all named authors.

Corresponding author

Correspondence to A. Arumugam .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The original online version of this Article was revised: The original version of this Article contained an error in the spelling of the author Sushmitha Lakshminarayanan which was incorrectly given as Sushmitha Lakshmnarayanan.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

Lakshminarayanan, S., Shereen, M.F., Niraimathi, K.L. et al. One-pot green synthesis of iron oxide nanoparticles from Bauhinia tomentosa : Characterization and application towards synthesis of 1, 3 diolein. Sci Rep 11 , 8643 (2021). https://doi.org/10.1038/s41598-021-87960-y

Download citation

Received : 18 September 2020

Accepted : 26 March 2021

Published : 21 April 2021

DOI : https://doi.org/10.1038/s41598-021-87960-y

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

This article is cited by

Biogenic nanoparticles: pioneering a new era in breast cancer therapeutics—a comprehensive review.

• Shahnawaz Ahmad Bhat
• Vijay Kumar
• Praveen C. Ramamurthy

Discover Nano (2024)

Characterization and nematicidal potential of copper, iron and zinc nanoparticles synthesized from Tridax procumbens L. Extract on Meloidogyne incognita infected cabbage plants

• Oluwatoyin Fabiyi
• Agbaje Lateef
• Gabriel Olatunji

European Journal of Plant Pathology (2024)

Greener Assembly of Nano Catalysts and Sustainable Applications of Magnetically Retrievable and Plasmonic Nano Catalysts

• Ananya Sridhar
• Cyril Koshy Sunil
• Suma Sarojini

Topics in Catalysis (2024)

Synergetic effect using green nano-zero-valent iron and biodegradation (Pseudomonas BSPS_PHE2) for cyanide and phenol removal in coke-oven wastewater

• Megha Tyagi
• Sheeja Jagadevan
• Deepak Kukkar

Clean Technologies and Environmental Policy (2024)

Biosensing and anti-inflammatory effects of silver, copper and iron nanoparticles from the leaf extract of Catharanthus roseus

• Mst.Jesmin Sultana
• Al Ibne Shahariar Nibir
• Fazle Rabbi Shakil Ahmed

Beni-Suef University Journal of Basic and Applied Sciences (2023)

By submitting a comment you agree to abide by our Terms and Community Guidelines . If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Sign up for the Nature Briefing: Translational Research newsletter — top stories in biotechnology, drug discovery and pharma.

Advertisement

A narrative review of the synthesis, characterization, and applications of iron oxide nanoparticles

• Open access
• Published: 10 October 2023
• Volume 18 , article number  125 , ( 2023 )

Cite this article

You have full access to this open access article

• Joseph Ekhebume Ogbezode 1 , 2 ,
• Ucheckukwu Stella Ezealigo 1 ,
• Abdulhakeem Bello 1 , 3 , 4 ,
• Vitalis Chioh Anye 1 &
• Azikiwe Peter Onwualu 1  

3488 Accesses

7 Citations

1 Altmetric

Explore all metrics

The significance of green synthesized nanomaterials with a uniform shape, reduced sizes, superior mechanical capabilities, phase microstructure, magnetic behavior, and superior performance cannot be overemphasized. Iron oxide nanoparticles (IONPs) are found within the size range of 1–100 nm in nanomaterials and have a diverse range of applications in fields such as biomedicine, wastewater purification, and environmental remediation. Nevertheless, the understanding of their fundamental material composition, chemical reactions, toxicological properties, and research methodologies is constrained and extensively elucidated during their practical implementation. The importance of producing IONPs using advanced nanofabrication techniques that exhibit strong potential for disease therapy, microbial pathogen control, and elimination of cancer cells is underscored by the adoption of the green synthesis approach. These IONPs can serve as viable alternatives for soil remediation and the elimination of environmental contaminants. Therefore, this paper presents a comprehensive analysis of the research conducted on different types of IONPs and IONP composite-based materials. It examines the synthesis methods and characterization techniques employed in these studies and also addresses the obstacles encountered in prior investigations with comparable objectives. A green engineering strategy was proposed for the synthesis, characterization, and application of IONPs and their composites with reduced environmental impact. Additionally, the influence of their phase structure, magnetic properties, biocompatibility, toxicity, milling time, nanoparticle size, and shape was also discussed. The study proposes the use of biological and physicochemical methods as a more viable alternative nanofabrication strategy that can mitigate the limitations imposed by the conventional methods of IONP synthesis.

Similar content being viewed by others

Core to concept: synthesis, structure, and reactivity of nanoscale zero-valent iron (NZVI) for wastewater remediation

Synthesis, Characterizations and Applications of Iron Oxide-Based Nanocomposites

Nanoscale zero-valent metals: a review of synthesis, characterization, and applications to environmental remediation

Avoid common mistakes on your manuscript.

Introduction

Study background.

The production of atomic and molecular particles between 1 and 100 nm is known as nanotechnology and nanoscience, respectively [ 1 , 2 ]. Nanomaterials are substances that exhibit the characteristics of microscopic objects. Optics [ 3 , 4 ], mechanics [ 5 , 6 ], bioengineering [ 6 , 7 ], medicine [ 8 , 9 ], and environmental remediation [ 10 , 11 ] are all engineering disciplines that utilize these particles. According to the literature [ 9 , 10 , 11 ], numerous strategies have been employed to produce metallic nanoparticles (MNPs). Nanoparticles (NPs) are often produced using chemical [ 12 ], biological [ 13 ], and mechanical [ 14 ] techniques. Physical and chemical processes are used to produce metal/metal oxide nanoparticles [ 15 ]. However, the limitations of these techniques reveal that the synthesis of metal and metal oxide nanoparticles necessitates the use of toxic, environmentally unfriendly, and highly reactive reducing agents [ 16 ]. This biological compound includes sodium hydroxide, hydrazine hydrate, wheat, glucose, xylose, and vitamin C [ 17 ]. Given that nanoparticle synthesis relies on the use of nontoxic methods to avoid the involvement of hazardous chemical agents [ 18 ], it is imperative for researchers to consistently endeavor to develop highly efficient biochemical reduction agents and acquire environmentally friendly resources for the production of nanoparticles.

Extensive research has been conducted on iron nanoparticles (FeNPs) [ 19 , 20 ] due to their promising application in various fields, including medicine, environmental remediation, and sewage treatment. In addition, the process of water purification can be effectively achieved by using nanoscale and nanofiltration techniques [ 21 , 22 ]. Recent advancements in nanotechnology have examined the importance of removing toxic compounds from nanoparticles by using an environmentally friendly technique. For instance, iron nanoparticles (FeNPs) in water and the environment compete favorably with hazardous chemical contaminants [ 23 ]. Utilizing environmentally friendly nanoparticle production processes has the potential to expedite advancements in the biological, economic, and technical domains [ 24 ]. This article provides an assessment of the economic, biological, and environmental implications linked to the production of iron and iron oxide nanoparticles, considering their extensive range of potential applications.

Synthesis of iron oxide nanoparticles

Considering the wide range of physical and chemical properties exhibited by IONPs, researchers continue to show substantial interest in their production and application. This is due to the various structural and non-structural uses that IONPs provide [ 25 ]. For instance, IONPs have various properties, including strong magnetic behavior, phase microstructure, mechanical and thermal properties, etc. These properties indirectly influence their suitability for use in scientific and engineering fields as well as multidisciplinary purposes. Many works of literature have attempted to identify and delineate the different systematic approaches used in the synthesis and applications of IONPs. To appreciate the usage of nano-materials, there is a need to conduct an in-depth review of existing research on metal oxide nanoparticles and nanocomposite-related articles. However, the state of the art in nanoparticle research encompasses their diverse applications, while the selection of nanoparticles is driven by their exceptional properties. This work's novelty stems from its innovative synthesis approach, addressing a knowledge gap in precise nanoparticle control, and its contribution to advancing energy storage applications. The knowledge gap further expositions of recent trends in nano-synthesis, and the application of IONPs in modern-day nanotechnology has been enumerated in the study. Despite the notable strides in nanoparticle research, several knowledge gaps persist. A prominent gap lies in the synthesis of nanoparticles with precise control over their characteristics, particularly regarding size, shape, and surface chemistry. Furthermore, understanding the long-term effects of nanoparticles on human health and the environment remains a challenge, prompting the need for safer and more sustainable synthesis methods. Therefore, this paper presents a comprehensive overview of recent articles that have made significant contributions to the advancement of knowledge in the areas of synthesis, characterization, nanofabrication, and applications of IONPs.

Overview of research articles on IONPs and their significance

The significance of synthesized IONPs cannot be overemphasized due to their extensive potential applications in various disciplines such as science, engineering, and medicine. The application of IONPs includes but is not limited to electronic appliances, automobiles, biomedicine, water purification, environmental remediation, and drug delivery systems. Saif et al. [ 26 ] conducted a green synthesis of zero-valent metallic iron (ZVMI) from hematite and magnetite and evaluated the ecotoxicological contrast between green and non-green iron nanoparticle synthesis. The study provides a detailed summary of the latest advancements in nanoscience and nanotechnology in the production of new nanomaterials (NMs). The purpose of the study explains the negative impact of supplementary and derivative chemicals on nanofabricated materials. The review validates the green synthesis strategy for the production of zero-valent metallic iron (ZVMI) from hematite and magnetite, as well as their application in environmental pollution and the water filtration process. The paper also provided an ecotoxicological contrast between green and non-green IONP synthesis.

Natarajan et al. [ 27 ] describe numerous approaches for producing magnetic iron oxide nanoparticles (MIONPs) for biomedical applications, surface modification, and cytotoxic effects. It also provides a comprehensive understanding of the potential state-of-the-art technique required to mitigate the cytotoxic effect of MIONP free radicals in industrial and biomedical applications. In addition, it provides a viewpoint on surface-modified MIONPs in medicinal and industrial applications for general well-being.

Rosen et al. [ 28 ] describe the use of functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for cancer and solid tumor diagnosis and treatment. The study concluded that functionalized SPIONs techniques are superior to magnetic resonance imaging for cancer and solid tumor diagnosis and treatment.

Kolhatkar et al . [ 29 ] highlight the unique production and application of different nanoparticles. The shapes, sizes, and elemental composition of these magnetic nanoparticles were studied. This research also provided insight into several methods of adjusting magnetic nanoparticles for greater effectiveness and specific use. Khan et al . [ 30 ] provided a comprehensive review of the synthesis, application, and toxicity of nanoparticles made from various materials (ceramics, metals, polymers, etc.) with particle sizes between 1 and 100 nm. The characteristics of produced nanoparticles are dependent on their size, shape, and crystalline structure. The presented knowledge supports the potential of the produced nanoparticles for extensive use in medical, imaging, energy-based research, and environmental applications.

Jalil et al. [ 31 ] synthesized hematite (Fe 3 O 4 ) NPs from its natural iron ore using a mechanical alloying process. The morphological, mineralogical, and phase composition of the produced Fe 2 O 3 samples were analyzed by SEM, XRD, and XRF. The results of XRD and XRF analyses of the synthesized sample exhibit similar and consistent properties. The study demonstrates that the nano-hematite (Fe 2 O 3 ) phase produced by mechanical or ball milling is crucial to the magnetic behavior of natural iron ore sources for the production of electromagnetic devices.

Ganapathe et al . [ 32 ] synthesized magnetite (Fe 3 O 4 ) NPs using a ball-milling process. The results of the XRD and XRF analyses exhibit similar and consistent properties. Concise information about the most recent methodologies and developments in magnetite nanoparticle synthesis, with a focus on their possible applications. The article provided a platform for future research by expanding our understanding of the possible applications of new organic and inorganic materials through case studies of their use in vitro and in vivo. Ali et al . [ 33 ] provided an overview of recent advancements in the synthesis, characterization, and applications of iron oxide nanoparticles with enhanced characteristics. The paper provides a comprehensive summary of IONP preparation processes, their applications, and potential limitations. The objective of this study was to provide additional extensive data on the present research interest in IONP production, from synthesis to characterization and application. Petrovský et al . [ 34 ] investigate the magnetic properties of magnetite nanoparticles produced from the stoichiometric combination of hematite ore samples with metallic iron particles in an inert atmosphere using the mechanical ball-milling technique for a predetermined time. It also provides additional support for the influence of magnetic properties and hardness on magnetite NPs produced by ball milling in the presence of a hot inert gas atmosphere. This is based on their relevance and applications in water filtration and environmental remediation. Thus, the metal-ion-sensing potential of IONPs made it possible for their usage in heavy metal elimination from polluted water due to their minor size, magnetic potential, and larger surface area.

Singh et al. [ 35 ] synthesized nanocrystalline FeCr alloy using the mechanical alloying method. The review is based on the need to probe the challenges involved in the thermal processing of synthesized iron-alloyed nanoparticles using oxidation-resistant nanocrystalline materials. It was concluded that it was necessary to troubleshoot the structural defects in nanocrystalline FeCr alloy. It is quite imperative to introduce similar nanostructure alloys to ascertain grain compactness within the metal matrix structure of the base particle. Mohapatra et al . [ 36 ] provide a comprehensive review of the preparation and application of α-Fe 2 O 3 NPs synthesized by precipitation method. Iron oxide properties such as goethite (α-FeOOH), hematite (α-Fe 2 O 3 ), and maghemite (γ-Fe 3 O 4 ) were synthesized according to their size, crystalline structure, and magnetic properties. The synthesized iron oxide particles were extensively substituted in biomedical, catalytic materials, magnetic recording devices, wastewater treatment, and medicine. The review explains the basic classifications of nanoparticles, the top-down approach and bottom-up approach, and the different forms of iron nanoparticle synthesis. It also explains how iron oxide nanoparticles can be synthesized with less energy utilization and decreased particle size.

Irfan et al . [ 37 ] explain the basic classifications of NPs (i.e., organic, ceramic, non-organic, and carbon-based NPs) and the kind of technological basis for their synthesis and characterization. The top-down approach and the bottom-up approach are the two major techniques used in nanoparticle synthesis. Also, metal and metal oxide nanoparticles (MONPs) are direct sub-classifications of inorganic nanoparticles. Classification of nanoparticles into one-dimension, two-dimension, and three-dimension forms is done. The basic techniques and novel applications of different nanoparticles based on their mechanical properties were reviewed.

Guo et al . [ 38 ] reviewed the basic techniques and novel applications of different nanoparticles based on their mechanical properties. Special nanoparticle mechanical properties vis-à-vis their interracial forces acting on the surface and the basics of physics were explained. Young modulus, hardness, friction, and abrasion were surveyed, as well as the parameters involved in reinforced or coated nanoparticles and nanofabrication operations. The study gave a summary and future perspective on the effect of mechanical properties, and the parameters were involved in reinforced or coated NPs and nanofabrication operations.

Satyanarayana, et al . [ 39 ] also reviewed various techniques for the preparation of nanomaterials, which were enumerated. Synthesized NPs, which include mechanical, electrochemical, sonochemical, micro-emulsion, and physical and chemical reduction, were discussed in detail. The paper postulates a future perspective into research for NP synthesis, operations, production strategy, and their applications.

Ali et al . [ 40 ] further gave a comprehensive review of the synthesis, applications, and challenges involved in the production of iron oxide nanoparticles. The review further enumerates the various methods of iron oxide nanoparticle synthesis according to works of literature, with emphasis on biocompatibility, magnetic characteristics, and morphology control. The report revealed that magnetic iron oxide nanoparticles (MIONPs) with good magnetic susceptibility are better applied in biomedical research, drug delivery, and pharmaceutics. The study was designed to give up-to-date information on the synthesis, characterization, and applications of iron nanoparticles. Samrot et al . [ 41 ] reviewed the numerous fields of applications of SPION that were elucidated. The various methods of SPION synthesis, which include physical, chemical, and biological methods, were also elaborated. The report shows that the synthesis and characterization of SPIONs are properties- and feature-based. The exceptional magnetic property of SPIONs encourages its application as a contrast agent in magnetic resonance imaging and for biomedical purposes. The report also elaborated on the synthesis and application of surface-functionalized MIONPs. This nanomaterial has elaborate applications in biomedical, drug delivery, environmental remediation, radiation therapy, tissue engineering, etc. Wu et al . [ 42 ] elaborated on the synthesis and application of surface-functionalized magnetic iron oxide nanoparticles (SFMION), which have wide applications in the field of biotechnology. Recent developments in the preparation strategies and practical applications of SFMION were elaborately discussed. The properties of functionalized iron oxide nanoparticles, such as stability, biocompatibility, and surface function characteristics, were also briefly discussed. The study was concluded by enumerating the major challenges associated with the production and synthesis of the NPs, while future perspectives for research were suggested.

Dobson [ 43 ] reviewed the use of synthesized IONPs for magnetic devices and drug delivery systems and stressed the need for further studies in gene and drug delivery operations. The study provided an explanation of the use of various magnetic NP designs for biomedical purposes, including clinical and animal trials. The contribution to nanoparticle research established the need for further studies in gene and drug delivery operations. The report stressed the need to further advance the applications of magnetic nanoparticles for tumor treatments and clinical applications. Wu et al . [ 44 ] review focuses on the strategies and development of recent advances in the synthesis, characterization, and applications of functionalized IONPs in biomedicine. The study considers the various challenges, functionalized strategies, and problems involved in the bio-applications of IONPs and their future research prospects. Xu et al . [ 45 ] explained the recent advances in the use of iron oxide nanoparticles for wastewater treatment and gave future research perspectives on the likely challenges and solutions. Iron oxide coated with gold nanoparticles was synthesized using the sonochemistry method. The paper explains the recent advances in the use of IONPs as a cleanup technological strategy for wastewater treatment in the modern age. The study bridges the gaps and limitations involved in the various synthesis, characterization, and application of IONPs for water purification. The work also gave future research perspectives on the likely challenges and solutions that may affect the continued use of such water purification methods and their environmental impact.

Gul, et al . [ 46 ] attempted to substantiate the recent advances in the production and application of magnetic IONPs as a theranostic agent. Several methods of synthesizing magnetic iron oxide nanoparticles were enumerated, and the connections between the synthetic routes, magnetic properties, and size of the nanoparticle were extensively investigated. Generally, the importance of IONPs and composites is enshrined in their vast application in wastewater treatment, environmental remediation, biomedical and electrical appliances, microchips, superparamagnetism, magnetic resonance imaging (MRI), cancer treatment, etc. The extent of their importance is based on various factors, which vary from IONP type, size, shape, magnetic properties, physical properties, morphological tendencies, etc. For instance, the synthesis of inorganic metals coated with IONPs has gained research attention in recent times with applications in cancer cell eradication and biomedical processes. Dheyab, et al. [ 47 ] performed a comprehensive review of the synthesis of iron oxide coated with gold nanoparticles (Fe 3 O 4 @AuNPs) using the sonochemistry method. This involves the modification of chemical reactions using ultrasound. The study addresses the fundamental principles of the sonochemistry approach. It also described the properties of the synthesized IONP products using the sonochemistry method through the summary of key works of literature from relevant publications using case studies such as Fe 3 O 4 NPs, AuNPs, and Fe 3 O 4 @AuNPs [ 48 , 49 , 50 ]. A simple, rapid stabilization process of Fe 3 O 4 NPs using the citric acid modification method was conducted by Dheyab et al. [ 51 ]. The study employed the rapid method of one-step co-precipitation to synthesize magnetite NPs in the presence of magnetized citric acid in the form of an aqueous colloidal solution (Fe 3 O 4 @CA). The as-prepared Fe 3 O 4 @CA had a Zeta potential value increment from − 31 to − 45 mV due to its high magnetic saturation capacity. Thus, the synthesized IONPs do possess a high magnetic saturation value of 54.8 emu/g, which in turn leads to promising sustainability for biomedical applications. These IONPs can be used as theranostic agents for cancer cell eradication, biomedical processes, and drug delivery systems. Several studies also attempted to use the sonochemical approach for the synthesis of Fe 3 O 4 @Au NPs used for cancer cell eradication via magnetic resonance imaging (MRI) and computed tomography. The IONPs synthesized in such gold (Au) powder were precipitated to produce NPs with a size of 22 nm in 5 min and have proven to be efficient as a theranostic agent through a sonochemical approach for cancer cell eradication [ 52 , 53 ]. The study concluded because of the potential applicability and future research prospects of IONPs and their importance as theranostic agents for cancer cell eradication, biomedical processes, and drug delivery systems. For easy understanding, this paper specified that the production of IONPs was classified into two different ways based on their method of preparation and application in various fields of study, as depicted in Fig.  1 .

Top-down and bottom-up methods of nanoparticle production [ 25 ] Copyright 2011: NanoTrust-Dossier

The two basic strat e gies for the production of nanomaterials are top-bottom and bottom-up approaches. The top-bottom method involves mechanical crushing of the base materials, while the bottom-up method involves a chemical process to alter the structure of the base materials, depending on the chemical characteristics of the nanoparticles as depicted in Fig.  1 . Also, Fig.  2 shows a comprehensive summary on the production route for metal/metal oxide nanoparticles from the known conventional methods.

Overview of the production processing of nanomaterials

The top-bottom/mechanical production method

For the generation of NPs, the top-down/mechanical production method employs a mechanical/milling crushing process that is time-consuming and energy-intensive [ 54 , 55 ]. This procedure is time-consuming and employs mechanical abrasion procedures that are energy-intensive. Metallic oxide continues to be the conventional source of material that is pulverized by a stoichiometric operation before being crushed using high-energy ball mills [ 56 ]. The mills are manufactured from a high-strength steel material with superior mechanical hardness [ 57 ]. As depicted in Fig.  2 , the mechanical/physical/crushing method produces nanoparticles that are considerably larger than those produced by the chemo-physical method.

The bottom-up/chemical production method

The bottom-up/chemical production method involves co-precipitation and aerosol activities and generates nanomaterials with superior geometric structures and size ranges. These nanomaterials are formed by homogeneous nucleation via the solid–liquid reaction or by condensation reaction in the gas–solid reaction.

This method also involves an atomic-molecular interaction between a nanoparticle of base metallic oxide and a chemical reducing agent. This technique generates a sophisticated strategy for the synthesis of nanoparticles, which takes delight in its ability to generate nanomaterials with superior geometric structure and size ranges [ 58 ]. Figure  3 depicts the schematics of IONPs synthesis using co-precipitation and aerosol activities. Nanoparticles produced using any of the aforementioned physiochemical processes are formed either by homogeneous nucleation via the solid–liquid reaction or by condensation reaction in the gas–solid reaction, as well as particle coalescence technique from particle fusion, which has applications in wall reactors, plasma jets, and carbon nanotubes [ 59 ]. Through physiochemistry, as shown in Fig.  4 , nanoparticles created by gas–solid chemical reactions yield vapor product materials [ 60 ].

Overview of nanomaterial production by mechanophysical process

Overview of nanomaterial production by physiochemical process

Conventional routes for IONPs synthesis and extraction

Over the decades, different authors have postulated various methods for the synthesis and characterization of IONPs [ 61 , 62 , 63 , 64 , 65 ], including physical [ 66 ], chemical [ 67 ], or biological [ 68 ]. Recently, a few pieces of literature have attempted to combine two or more methods of the known conventional technique of synthesizing nanoparticles [ 69 , 70 , 71 , 72 ]. Physicochemical, biochemical, and biophysical approaches are included. No published effort has been able to simultaneously synthesize and characterize IONPs utilizing all three conventional approaches. This is indeed a new area of nanotechnology research in which researchers can advance the applications of nanoparticles beyond the known fields of study, as the literature demonstrates that the method employed in the synthesis of nanomaterials determines their quality in terms of sizes, shapes, magnetic behavior, surface functionality, and applicability [ 73 , 74 ]. Listed below are several conventional techniques for producing nanomaterials. For the sake of clarity, a systematic review of the synthesis and characterization of iron oxide nanoparticles (IONPs) was performed. The study also gives a holistic background on the various production routes of IONPs and investigates their nanocrystalline phase structure and characteristics in real-time experiments. It also summarizes diverse applications of IONPs and iron oxide nanocomposite-based materials in wastewater filtration, environmental remediation, plant development, drug delivery, bone repair, cancer cell eradication, tissue regeneration, and the biomedical field. Additionally, the influence of their mineralogical properties, morphology, phase structure, biocompatibility, magnetic properties, toxicity, nano-processing time, nanocrystalline size, and shape was also discussed.

Synthesized iron oxide nanoparticles’ mechanical alloying method

This method for extracting NPs of iron oxide is an energy-intensive procedure that includes a grinding medium, making it a completely mechanical operation [ 75 ]. A ball-mining machine is used to crush natural iron oxide particles into polycrystalline NPs less than 5 nm in size [ 76 ]. The milling procedure exerts abrasive force for approximately 23 h. The approach is capable of providing a nanoscale particle size reduction impact on raw iron oxide material [ 77 ]. The ball-milling machine utilized for the mechanical alloying of iron oxide particles is rotated at 300 rpm for 20 h, and the morphological and microstructural changes of the grounded iron oxide particles are examined using XRD and high-resolution SEM micrographs [ 78 ]. Using X-ray fluorescence (XRF) and energy-dispersive spectroscopy (EDS), the elemental composition of the ground FeNPs was examined. Using a magnetic detecting device, such as the vibrating-sample magnetometer, reveals other properties, such as magnetic behavior (VSM).

Synthesized iron oxide nanoparticles by mechanochemical method

A solid-state chemical reaction technique is used to synthesize iron oxide nanoparticles by collective annealing and milling. Iron oxide particles are annealed at temperatures between 300 and 700 degrees Celsius [ 79 ]. Using a ball-milling machine, the iron oxide particles are crushed into powered NPs with an average size range of 10 to 100 nm. The produced NPs can be evaluated utilizing techniques such as X-ray diffractometry (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), electro-dispersive spectrometry (EDS), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). In recent years, the mechanochemical approach has been used to create iron oxide nanoparticles due to their unusual chemical and physical properties [ 80 ]. This method is easy, has a high yield scale, and has minimal economic consequences, but could present a difficulty in their post-processing stages and applications [ 81 ]. Mechanochemical nanoparticle processing of iron/iron oxide is a novel technology for iron ore production and characterization. The method combines concurrent procedures that combine ball-milling and solid-state displacement methodologies with a low energy demand and a high propensity toward environmental friendliness [ 82 ].

However, the development of the mechanochemical approach to NPs for large-scale manufacturing could present a difficulty in their post-processing stages and applications [ 83 ]. Several industrial preparations of iron oxide nanoparticles have been done to improve the nanomaterials' physical and magnetic properties [ 84 , 85 ]. This method is restricted to the anticipated industrial uses of the synthesized iron nanoparticles, such as pigmentation [ 86 ], catalysis [ 87 ], wastewater treatment [ 88 ], gas purification [ 89 ], combustion [ 90 ], electrochemical [ 91 ], co-precipitation [ 92 ], and superparamagnetism [ 93 ]. In light of this, the mechanochemical approach remains a pollution-free and eco-friendly physical technique due to its absence of organic solvents and ecological cleanliness [ 94 ]. Consequently, the primary objective of this iron nanoparticle manufacturing method is to manufacture nanoparticles that are environmentally friendly and support the green synthetic approach to nanomaterial fabrication.

Synthesized IONPs by chemical and biological methods

The importance of producing green nanomaterials with little environmental impact through the use of green technology cannot be overstated. There is a need to commence laboratory-scale nanoscience-related research due to the constraints of massive material acquisitions and their cost implications, which are key obstacles to the sustainability of nanodevice manufacture in the engineering industry. The chemical and biological methods of nanoparticle synthesis are commonly employed in nanosciences to synthesize, extract, and manufacture nanomaterials for laboratory-scale research experiments [ 95 ]. This technology has demonstrated its potential for generating environmentally friendly nanomaterials with a minimal economic impact on end-users [ 96 ]. Over the years, several biochemical methods have been used to generate nanoparticles from bulk materials, including co-precipitation, hydrothermal, sol–gel, inert gas condensation, microwave-assisted method, micro-emulsion, sputtering, chemical vapor deposition, sonochemical vapor deposition, physical vapor deposition, liquid infiltration, rapid solidification based on their atomic and molecular structure [ 97 ]. This is made feasible by introducing additional particles into the metal matrix of the base materials with the aid of biological and chemical reagents [ 98 ]. At specific chemical energies, different ionic exchanges occur to restructure and rearrange the microstructure characteristics of the basic materials [ 99 , 100 , 101 , 102 ]. Numerous published publications have utilized the various biochemical methods of nanoparticle extraction to manufacture even more challenging engineered materials [ 103 , 104 , 105 , 106 ]. In this study, the biochemical approaches for manufacturing NPs of iron and iron oxide were examined. According to Iqbal et al. [ 107 ] and Issa et al. [ 108 ], the biochemical techniques used to synthesize iron oxide nanoparticles include co-precipitation, hydrothermal, sol–gel, inert gas condensation, microwave-assisted method, micro-emulsion, sputtering, chemical vapor deposition, sonochemical vapor deposition, physical vapor deposition, liquid infiltration, rapid solidification, and so on. Baaziz et al. [ 109 ] generated iron oxide nanoparticles in coated sand using the biochemical approach; the purpose of the study was to solve water treatment-related problems via the biochemical manufacture and characterization of iron oxide nanoparticles from coated sands.

Co-precipitation technique

Wu et al. [ 110 ] used the co-precipitation method to synthesize magnetite particles; the co-precipitation strategy used in the study involves varying the reactant concentration and reaction temperature, as these variables affect the process parameters as well as the microstructural and magnetic properties of the base material. The product exhibits high-quality, crystalline NPs with applications in water purification and medication delivery. Chen et al. [ 111 ] used extraction solvents to generate iron nanoparticles, and XRD, SEM/EDS, TGA, and FTIR analyses were performed to evaluate the produced magnetite NPs. Tri-butyl phosphate (TBP) and tri-octyl phosphine oxide (TOPO) were utilized as extraction solvents. Both heptanol and 2-ethyl-hexanol are employed as diluents and modifiers [ 112 ]. The analysis confirms that after magnetite nanoparticles were exposed to various solvents, the Scherrer equation [ 113 ] demonstrated that all investigated extraction solvents had a substantial effect on the sample's mean crystallite size. Co-precipitation production of iron oxide nanoparticles uses hydrated ferric chloride [ 114 ], deionized water [ 115 ], and ammonium hydroxide [ 116 ] as chemical reagents. Magnetite crystals are produced by the ionization of chemical reagents in the presence of nitrogen gas at varied temperatures and with strong stirring [ 117 ]. Hence, the benefits of co-precipitation over alternative biochemical approaches for the synthesis of iron oxide nanoparticles include its simplicity, fast preparation at low temperatures, and energy efficiency [ 118 ].

Reverse co-precipitation technique

Estelrich et al. [ 119 ] completed a reverse chemical co-precipitation synthesis using an active reduction reagent as a stabilizer on magnetite (Fe 3 O 4 ) NPs. The characteristics of Fe 3 O 4 and Fe 3 O 4 NPs coated with dimethyl sulfoxide (DMSO) were compared with those of the uncoated material. Using X-ray diffraction (XRD) and scanning electron microscopy (SEM), the microstructural and mineralogical features of both samples were investigated. The results demonstrated that DMSO-coated sample particles respond better to Fourier studies and SEM examination than uncoated Fe 3 O 4 nanoparticles [ 120 ]. Co-precipitation and reverse co-precipitation procedures are time-consuming, have repeatability issues when employing base materials with varying reactant rates, and have the potential to introduce foreign particles into the metal matrix structure of the iron oxide nanoparticle product [ 121 ].

Hydrothermal technique

The hydrothermal approach for generating iron oxide nanoparticles by oxidizing iron has gained remarkable popularity among nonscientists in recent years [ 122 ]. The hydrothermal synthesis of iron oxide nanoparticles has applications in the fields of superconductors, microporous crystals, complicated iron oxide ceramics for solid electronic conductors, and magnetic materials. The hydrothermal breakdown involves a heat treatment in which iron nanoparticles ranging in size from 15 to 25 nm are generated [ 123 ]. Under certain temperatures and pressures, nanoparticles of iron oxide are produced in a reactor through crystallization. The manufactured nanoparticles are crystal growth products derived from warmed iron oxide materials employing organic solvents and precursor solutions as reagents. Hydrothermal processing of iron oxide nanoparticles has the advantage of producing homogeneous nanoparticles with reduced size, shape dispersion, and uniform nanostructure crystallinity [ 124 ]. Nanoparticles must be created in high-temperature, high-pressure reactors, which has significant financial ramifications.

Sputtering technique

Sputtering is an atomic ejection-based process in which charged particles are ejected off the surface of a substance. It is a phenomenon that occurs when a particle with extremely high kinetic energy strikes the surface of a metallic material [ 125 ]. On the substrate layer of the targeted material's surface, sputtered atomic particles are deposited. There are three types of sputtering procedures for atomic particle ejection from their base materials: which include reactive sputtering, DC sputtering, and magnetron sputtering. This includes reactive sputtering, in which an inert gas (such as argon) is employed as the sputtering gas and is activated [ 126 ]. At all costs, avoid the reaction between the inert gas and the sputtered atom. In this procedure, powered sputtering gas or inert gas is used to remove oxides and nitrides off the surface of metals (i.e., iron oxide). DC sputtering is yet another form of sputtering technology [ 127 ]. This occurs when a substantial number of charged particles expel ionized atoms (or molecules) (i.e., plasma). After the energized ions from the plasma contacted the target, the charged particles returned to their starting state of atomic neutralization. The neutralized ion is deposited as nanoparticles on the surface of the target substance. The shapes and sizes of nanoparticles created by the aforementioned sputtering technique depend on the substrate's temperature, layer thickness, and annealing time. Peng et al. [ 128 ] and Roy et al. [ 129 ] have examined thin films deposited by an iron oxide target by sputtering. A blend of hematite, magnetite, and a silicon or glass substrate composes the foundation material. They found that the particles exhibit critical thickness growths as a result of a phenomenon known as substrate bias, which enhanced their magnetic properties. Sputtering techniques for creating IONPs are adaptable to nearly all material kinds, but their basic target materials are frequently costly. Sputtering target poisoning must be prevented through the use of a preventative control mechanism. [ 77 ]. Using a high-resolution transmission electron microscope (HRTEM), the crystallographic defect observed on the film surface of the produced iron oxide nanoparticles [ 130 ] was investigated. Several works of literature [ 131 , 132 , 133 ] have confirmed that metallic nanoparticles (NM) created by the sputtering approach have superior magnetic and microstructural properties compared to those produced by other bottom-up procedures. The greatest benefit of nanoparticles created by the sputtering technique is their adaptability to nearly all material kinds [ 134 ]. It is possible to manage the material composition to avoid unanticipatedly complex chemical processes. The downside of sputtering approaches for IONPs is that their basic target materials are frequently costly [ 135 ]. NPs are not energy-efficient; thus, sputtering target poisoning must be prevented through the use of a preventative control mechanism. Additional biological techniques for the creation of iron oxide nanoparticles include spark discharge [ 136 ], micro-emulsion [ 137 ], microwave-assisted methods [ 138 ], laser ablation [ 139 ], ultrasound [ 140 ], and the sol–gel approach [ 141 ].

Synthesized iron oxide nanoparticles’ mechanophysical method

Sahoo et al. [ 142 ] stated that the necessity of producing iron oxide nanoparticles stems from the fact that oxidizing iron into IONPs modifies its characteristics. According to scientific research, metallic oxide NPs are more reactive than their base metals [ 143 ]. This indicates that iron oxides are more reactive than nanoparticles of iron [ 144 ]. Thus, IONPs are often created by thermal decomposition, lithography, sputtering, and mechanical/ball-milling. These procedures are utilized as convectional physical procedures to create IONPs.

Mechanical/ball-milling technique

Arbain et al. [ 145 ] synthesized α-Fe 2 O 3 from natural iron ore using the mechanical alloying technique. Using SEM, XRD, and XRF, the morphological, mineralogical, and phase composition of the produced Fe 2 O 3 samples were analyzed. The XRD and XRF analyses of the synthesized sample reveal similar and consistent properties. Hence, the study demonstrates that the nano-hematite (α-Fe 2 O 3 ) phase formed by the mechanical milling process plays a crucial role in the magnetic behavior of its natural ore sources [ 146 ]. To determine the magnetic properties of nanoparticles, Chen et al. [ 147 ] produced magnetite NPs using the ball-milling process. The phase structure and mineralogical characteristics of the NPs were determined by XRD and XRF analysis. NPs with strong magnetic properties are the outcome of the stoichiometric mixing of hematite samples with metallic iron particles in an inert atmosphere over a predetermined period. The study provides additional support for the indisputable influence of magnetic properties and hardness on magnetite nanoparticles produced by ball milling in the presence of a hot, inert gas atmosphere.

Heat treatment/thermal decomposition technique

In general, the thermal decomposition heat treatment technique can be used to synthesize nanomaterials from iron oxides at temperatures exceeding 250 °C [ 148 ]. The technique of thermal decomposition is an endothermic procedure involving a chemical reaction. The chemical production of nanoparticles occurs when chemical bonds, or van der Waal forces, are disrupted by a hot reaction [ 149 ]. This heat of reaction is the temperature at which the chemical elements decompose. Using the thermal breakdown approach on iron oxides invariably results in the presence of NPs, which are further synthesized into nanomaterials according to their uses [ 150 ]. The produced nanoparticles are more beneficial in superparamagnetic, biomedical, drug delivery, and wastewater treatment applications of which FeNPs and IONPs are such nanomaterials. The limitations of superparamagnetic iron oxide nanoparticles are their inability to be stored for an extended period, their poor maintenance structures when agglomerated, and their instability [ 151 ].

When iron ore is heated to 265 °C, the general breakdown method creates monodispersed iron oxide nanoparticles, which can be functionalized by the direct reduction of single metal ions on the surface of IONPs at a high temperature [ 152 ]. At an annealing temperature of 250 °C, magnetite NPs decompose readily into maghemite (γ-Fe 2 O 3 ) NPs via an oxidation reaction [ 153 ]. Sun et al. [ 154 ] and Shao et al. [ 155 ] studied the size-controlled mechanism of monodispersed Fe 3 O 4 NPs by the thermal decomposition technique. The monodispersed character of the nanoparticles is a clear indicator that the magnetite crystal structure is changed into α-Fe 2 O 3 nanoparticles via thermal decomposition without the need for size reduction [ 156 ]. Consequently, functionalized iron oxide nanoparticles can be generated by the direct reduction of single metal ions on the surface of IONPs at a high temperature.

Lithographic technique

The lithographic process is one of the physical approaches used to produce nanoparticles. The procedure has proven to be highly costly and energy-intensive over time [ 157 ]. Nanomaterials created by the lithographic process have several uses in electronic devices and computer accessories. Lithographic synthesis is a top-down technique that can be utilized to create micro- and NPs. Fusion-ion lithography, electron beam lithography, photolithography, nano-imprint lithography, and dip-print lithography are some of the known diverse methods of synthesis [ 158 ]. It has numerous uses, including additive manufacturing and semiconductors.

Parameters of synthesized IONPs

Size and shape of ionps.

Generally, most production parameters involved in iron or ferrous metal-related nanofabrication processes are interdependent. Therefore, it is important to understand the correlation between other nano-processing parameters and the precise size of iron oxide nanoparticles. For instance, the ferromagnetic behavior of maghemite and magnetite is similar when their particles are synthesized at a nano-sized range between 15 nm and − 45 nm [ 159 ]. Also, nano-size variations of IONPs are produced based on their functionality and applications in many known conventional processes, especially in magnetic and biomedical-related fields [ 160 ]. Therefore, to fully ascertain the precise size of iron oxide nanoparticles, it is important to understand the correlation between other nano-processing parameters (i.e., shape, magnetic property, etc.) and their various areas of applications [ 161 , 162 ]. For example, at the magnetism saturation point of 92 emu g −1 , γ-Fe 2 O 3, Fe 3 O 4, and α-Fe 2 O 3 revealed that both nanoparticles do exhibit weak ferrimagnetic and ferromagnetic tendencies at room temperature, respectively [ 163 ]. Furthermore, the superparamagnetic properties of iron oxide nanoparticles are revealed whenever their synthesized size is below 15 nm [ 11 ]. Also, depending on the degree of energy barrier due to anisotropic properties over thermal energy, IONPs can be processed to have NPs of 13–18 nm with better magnetic NPs in a size range of 13–18 nm and demagnetization tendencies [ 164 ]. Xing et al . [ 165 ] and Vergnat et al . [ 166 ] studied the production of iron nanoparticles from Fe 3 O 4 particles using a high-pressure gas condenser surrounded by a maghemite shell. The study revealed that the synthesized iron core nanoparticle has a size range of 10–20 nm. The shape and size of the iron nanoparticles are strongly influenced by the energy generated by the gas environment. The overall particle behavioral characteristics of the produced nanoparticles were investigated based on their superparamagnetic fractions and magnetic susceptibility to frequency dependence.

Lesiak et al . [ 167 ] studied the systematic production of FeNPs from recently discovered Fe 3 O 4 particles of distinct size ranges 85–5 μm in the Coloradan iron ore deposit in Mexico. The changes in mineralogical and morphological characteristics of the magnetite particles were done using XRD and Mossbauer spectroscopy. High-resolution transition electron microscopy (TEM) was used to investigate the crystallographic changes in sizes of the magnetite particles upon transition from micro-metric to nanometric structures [ 168 ]. The overall particle behavioral characteristics of the produced nanoparticles were investigated based on their superparamagnetic fractions and magnetic susceptibility to frequency dependence. In addition, the isothermal efficiency, coactivity, and remnant magnetization properties of the IONPs were investigated [ 128 , 169 ]. The study of NP sizes as reported in the literature reveals that the direct magnetic separation method could serve as an alternative approach to the production of metallic iron NPs, especially for Fe 3 O 4 materials that are acquired as run-off mines [ 170 ].

Another approach to ascertain the size and size distribution of IONPs is the use of morphological analysis of the synthesized particles using a transmission electron microscope (TEM), scanning electron microscope (OPM), and optical imaging micrograph (OPM). IONP size distribution within the metal matrix revealed the more precise size and shape of the grain boundary by intergranular paths along with the grain size [ 171 , 172 ]. The overall nanoparticle behavioral characteristics of the produced nanoparticles were investigated based on their superparamagnetic fractions and magnetic susceptibility to frequency dependence [ 138 , 173 ], and recent advances have been made in the areas of nano-imaging [ 174 ], magnetic resonance imaging [ 175 ], and size control [ 176 ] with diverse applications found mainly in biomedicine and drug delivery systems. In addition, IONP size separation [ 177 ] using TEM, where nanoparticles of similar shapes with almost the same size range are coerced or condensed within the functionary surface of the IONP metal matrix, can be classified based on their grain sizes and particle density within the phase metal matrix structure of the Fe-alloyed using the composite materials magnetic resonance imaging (MRI) technique [ 178 ].

Magnetic properties of IONPs

Numerous published articles have proposed a scientific strategy for transforming conventional IONPs into superparamagnetic IONPs via surface functionalization techniques. Loss of magnetism and disparity have been regarded as insurmountable obstacles for magnetic IONPs. These strategies include shell–core–shell, matrix dispersion structure, core–shell structure, and Janus-type structures, among others. The Janus structure improves the magnetic behavior of IONPs' base materials under the influence of a magnetic force field by employing functionalized magnetic IONPs as stabilizing nanomaterials. Loss of dissimilarity in magnetic nanoparticles is the ability of magnetic NPs to have less surface energy within their magnetic force field when smaller NPs join together to make larger particles for magnetic resonance imaging [ 179 ]. Also, the loss of magnetism is accompanied by chemical activity inside the metal matrix of IONPs. This activity destabilizes the NPs' crystal structure, which makes them less useful [ 180 ]. Several publications [ 181 ] have suggested different techniques to fix the structural damage that IONPs obtain from chemical activity, very large energy, and particle aggregation to fix the problem with their magnetic behavior. Hence, the damage restoration approach includes shell–core–shell, matrix dispersion structure, core–shell structure, and Janus-type structures, among others [ 182 ].

The core–shell structure involves encapsulating a microstructure of iron oxide with nano-coating materials [ 183 ]. These coating materials exist in the form of magnetic composites that travel into the nuclei of the IONP to fill the space within the crystal structure of the IONP's base materials and create stability within its elemental core shells. In the shell–core–shell structural strategy, two functional materials are positioned next to one another on magnetic IONPs [ 184 ]. These materials provide crystal support for the magnetic IONPs by shielding their core from chemical interactions that could compromise their colloidal stability inside their metal matrix crystal structure. These surface functionalization and protection materials, sometimes known as "shells," prevent any undesirable interactions or chemical activity from penetrating the core of IONPs. In addition, the physical strategy for performing the matrix dispersion experiment necessitates preventing tiny superparamagnetic nanoparticles from growing into larger but weaker magnetic IONPs [ 185 ]. In contrast, the Janus structure solves the issue of loss of disparity and magnetism in IONPs by employing functionalized magnetic IONPs as stabilizing nanomaterials, which improve the magnetic behavior of the IONPs' base materials under the influence of a magnetic force field. The Janus particle's magnetic field eliminates discrepancies and enhances the magnetic characteristics of the IONP's base material. The Janus structure modifies the microstructure of the IONP's base materials [ 186 ]. Thus, the microstructure of the IONPs' base material must be investigated to comprehend various methods for enhancing the magnetic properties of IONPs and resolving issues related to their superparamagnetic capabilities, such as loss of disparity and loss of magnetism.

Microstructure and morphological properties of IONPs

Most FeNPs and IONPs are characterized using SEM/EDS, XRD, TEM, etc., which are all powerful electromagnetic devices. Experiments are carried out under very specific conditions. Sun et al. [ 187 ] produced nanoparticles of magnetite iron oxide through the hydrothermal technique and examined their morphology in terms of the atomic or crystalline grain arrangements of the produced nanomaterials. The SEM image of the synthesized IONPs demonstrated the production of a highly crystalline particle with a considerable change in particle size (from 15 to 31 nm). Figures  5 and 6 depict the TEM and SEM micrographs and morphology of several IONPs manufactured in various published publications using various nanofabrication methods [ 188 ]. IONPs are typically subjected to TEM analysis to examine their morphology in terms of the atomic or crystalline grain arrangements of the produced nanomaterials [ 189 ]. Using the principle of electron diffraction of NPs, the morphology of selected portions of the phase microstructure is illustrated. Figure  5 (a) depicts a TEM picture of synthesized magnetite exhibiting an ellipsoidal particle form. IONPs produced by the hydrothermal technique have a typical Fe 3 O 4 nanostructure, while IONPs generated under high-temperature conditions have a dispersed microstructure with smaller particle sizes. The size and shape of manufactured IONPs are loaded into nanocarriers without altering their mechanochemical properties. In contrast, IONPs synthesized using the thermal breakdown approach, as represented in Fig.  5 (b), have a dispersed microstructure with smaller particle sizes, indicating that IONPs generated under high-temperature conditions contain nanoparticles with smaller sizes. At room temperature, the size dependency of high-quality α-Fe 2 O 3 NPs is examined in Fig.  5 (c) using the thermal decomposition approach. Notable is the fact that adjusting the ambient temperature of the manufactured IONPs may affect the magnetic and sizing properties of the nanoparticles. The IONPs underwent a change that modified the crystallinity structure from α-Fe 2 O 3 to Fe 3 O 4 . The TEM picture of IONPs was created using the physicochemical technique, as depicted in Fig.  5 (d). The micrograph also displays the number of IONPs contained within the nanocarrier. The size and shape of manufactured IONPs are loaded into nanocarriers without altering their mechanochemical properties. This implies that IONPs generated by inductive heating are monodispersed and uniformly distributed [ 190 ]. Figure  5 (e) depicts the characterization of the TEM image of IONPs generated by inductive heating. In the crystals of the microstructure, the synthesized IONPs are monodispersed, uniformly distributed, and have averagely lower dimensions than IONPs generated by other known conventional techniques. IONPs generated by chemical co-precipitation have a consistent size and comparable magnetic and chemical properties. Depending on the reaction precursor and time, the synthesized NPs produced by these procedures have averagely lower dimensions. In comparison with other known conventional techniques of IONP synthesis, IONPs synthesized by the inductive method have been demonstrated to be safer and easier to duplicate at an industrial scale. Accordingly, Fig.  5 depicts the size dependence of the IONPs generated by chemical co-precipitation Fig.  5 (f). The nanostructure of IONPs produced by the co-precipitation process demonstrates their monodispersed crystal structure [ 191 ]. Hence, IONP generated using this method has a consistent size and comparable magnetic and chemical properties. Similarly, TEM examination of certain IONPs produced using well-known conventional techniques revealed that the nanocrystals were homogeneous and possessed consistent properties. These characteristics are highly unique to the vast majority of IONP types, their synthesis, and their characterization methodologies, regardless of the iron oxide base materials employed.

Copyright: 2009, 2011, 2020 American Chemical Society; 2012, 2015, 2018 Elsevier

TEM micrographs of IONPs (Fe 3 O 4 / γ -Fe 2 O 3 ) with size range a 5–26 nm hydrothermal [ 23 ], b 5–24 nm thermal decomposition [ 32 ], c 4–20 nm, thermal decomposition [ 33 ], d 13–25 nm, physiochemical method [ 34 ], e 3–11 nm rapid induction heating method [ 35 ], f 10–24 nm, co-precipitation technique [ 40 ].

Copyright: 2008 American Chemical Society; 2009, 2011 Springer Science; 2012 Trans Tech; 2016, 2021 Elsevier

SEM micrographs of IONPs at 60 min a α -Fe 2 O 3 , mechanochemical process [ 147 ] b α-Fe 2 O 3, mechanical milling [ 151 ] c CoFe 2 O 4 , mechanical milling [ 156 ] d Fe 3 O 4 , co-precipitation [ 149 ] e Fe 3 O 4 , sol–gel method [ 158 ] f Fe 3 O 4 , chemical co-precipitation [ 159 ].

In addition, IONPs (Fe 3 O 4 /Fe 2 O 3 ) can be synthesized by hydrothermal, thermal decomposition, physiochemical, and rapid induction heating methods. Anjum et al. [ 192 ] synthesized IONPs using the solid-state chemical reaction movement technique, SEM/EDS, and thermogravimetric analysis (TGA) at a temperature range of 50–800 °C. The milling time for synthesized IONPs ranges between 30 and 60 min. The SEM micrograph illustrated in Fig.  6 (a) demonstrates that the phase of IONPs remains stable as particle size decreases with time. The SEM results concur with the XRD findings. When the TGA temperature rises, the iron phase of the produced nanoparticles changes. Hence, α-phase IONPs transform into γ-phases IONPs as the reaction temperature transitions from endothermic to exothermic and reaches 800 °C within 6 min. In Fig.  6 (b), the Fe 2 O 3 particle size was produced by mechanical milling for 15–60 min. The iron oxide phase of the described nanoparticle displays bulky or compacted grains with a strong oxygen trace [ 193 ]. The SEM result shown in Fig.  6 (b) is consistent with the results reported in the following figures, which demonstrated that the phase IONPs remain unchanged when the particle size decreases with milling time. This suggests that the dense microstructure phase of CoFe 2 O 4 produced by mechanical milling, as depicted in Fig.  6 (c), validates the nature of cobalt (Co) when burned in the presence of oxygen. Due to the presence of cobalt inside the produced IONP metal matrix, the iron phases of Fig.  6 (c) display an ice-cake-like appearance with a dense, whitish microstructure. Figure  6 (d) is the SEM micrograph of IONPs that were chemically produced utilizing the co-precipitation method. The properties of the presented SEM micrograph reveal a grain resembling a dense cake, as the IONPs phase is a dense structure devoid of microspores. Figure  6 (e) shows the SEM image of the synthesized IONPs, which are chemically produced by the sol–gel biochemical technique, and coated with sand. Due to the presence of silica particles in the coated sand, the morphology displays a spherical iron-phase microstructure surrounded by monodispersed micropores, which promotes stability and shields the NPs from acidic conditions. In contrast, Fig.  6 (f) displays a fibrous crystal structure of the iron oxide phase with widely spread, uniform-sized micropores. The properties of the presented SEM micrographs reveal a grain resembling a dense cake devoid of microspores, and a fibrous crystal structure of the iron oxide phase with widely spread, uniform-sized micropores. The scattered character of the Fe 3 O 4 phase may have been the outcome of the coated chemical agent's chemical action (i.e., C 12 H 25 OSO 3 Na). Hence, the SEM micrographs of Figs. 6 (a) through 6(f) reaffirmed the importance of the synthesis method, coating materials, temperature variations, and chemical agents utilized in the nanofabrication and nano-processing of metals and metallic alloys. Depending on the physical, chemical, and biological properties of the starting material, these processes have enormous effects on the nanoparticles' size, shape, magnetic behavior, morphology, and microstructure.

Biocompatibility effect and biological activity of IONPs

Magnetic iron oxide nanoparticles (MIONPs) have proven to be quite suitable for biological and biomedical applications because of their good saturation magnetization and high magnetization moment. These MIONPs include maghemite and magnetite. The importance of magnetic IONPs is mostly attributed to so many factors, which are in turn based on the method of synthesis and the proposed areas of application. These factors include size distribution, morphology, surface charge, surface chemistry, capping agents, etc. (see Fig.  7 ). MIONPs have also been exploited as model organisms in biosystem multifunctional nanomaterials based on their biological activity, which includes antibacterials, toxicity, and drug delivery [ 194 , 195 , 196 ]. The biological activity and biocompatibility of MIONPs can be influenced by their morphological properties, particle size, and magnetic behavior [ 197 , 198 ]. This often occurs during synthesis based on the nanocrystalline phase transformation characteristics and growth mechanism. The changes in properties of MIONPs based on their nanocrystals' growth mechanism and phase transformation mostly occur through the nucleation process during synthesis [ 199 ].

Schematics of magnetic IONPs synthesis, influential factors and applications in nano-biosystems

For instance, the mechanism of action during biological activities in MNIOPs entails a nano-interaction process between the crystal lattices in living cells and energy changes by the nucleation process. This involves the promotion of catalytic activities in enzymes to enhance or cause performance reduction in the cells [ 200 ]. Also, this interaction could lead to a malfunction or death of such living cells because of the energy changes caused by cell disruption integrity, which may occur within the cell membrane [ 201 ]. The synthesis of IONPs using biological methods is often referred to as green synthesis. It has several advantages over the traditional physicochemical methods. Figure  8 depicts the overview of the superiority of the biosynthesis method based on green nano-processing and application. The superiority of biologically synthesized IONPs over the physicochemical method is based on their wide applicability, cost-effectiveness, biocompatibility, reduced toxicity, narrow size distribution, environmentally friendly, reduced energy consumption, scalability, bio-functionalization, and biological catalysis tendencies [ 202 ].

Schematics of synthesis of IONPs using biological method and application [ 203 ]

The eco-friendly factor of the biosynthesis method of IONPs utilizes natural microorganisms and compounds to minimize hazardous waste and environmental impact and reduce the need for harsh chemicals and high temperatures in nanoparticle synthesis [ 204 ]. In the biological synthesis of IONPs, there is less likelihood of adverse reactions in living organisms because the use of biocompatible materials results in IONPs suitable for biomedical applications, imaging, and drug delivery systems with lower toxicity [ 205 ]. Also, biosynthesized IONPs have a biocompatibility advantage with enhanced surface modifications ensuring their suitable applications in pharmaceutics and biomedicine [ 206 ]. IONPs are mostly synthesized by mechanochemical process, mechanical milling, co-precipitation, sol–gel method, and chemical co-precipitation. However, these methods can promote or cause performance reduction in the cells, even malfunction or death of such living cells. IONPs synthesized by biological methods can yield narrow size distribution properties, which are essential for application in MRI contrast agents with uniform-sized NPs for better imaging quality [ 207 ]. To allow IONPs to suit some specific applications, the biological synthesis method can be fine-tuned to control the size, shape, and excellent multifunctional properties. Also, the use of microorganisms in the biosynthesis of IONPs can often be cultivated inexpensively. Thus, biological synthesis is less expensive than physicochemical methods because they require fewer chemicals and energy-intensive processes. Invariably, green synthesized IONPs biological synthesis at lower temperatures and pressures reduces energy consumption compared to high-temperature physicochemical methods. This lesser economic implication can be adapted for large-scale production as a result of reduced energy consumption, lower temperature, and pressure required during production, which is most crucial during industrial applications [ 208 ]. The bio-functionalization factor associated with IONPs is synthesized biologically for application in biomolecules (i.e., antibodies and enzymes) without any need for additional chemical modifications. In addition, the catalytic properties of biologically synthesized IONPs using microorganisms and enzymes can be highly efficient in reducing the need for chemical reagents and promoting the formation of such NPs. Thus, the superiority of biologically synthesized IONPs over physicochemical methods is dependent on specific requirements and applications in the modern-day nanofabrication process. The biological activities of IONPs can be maintained by molecule traffic control and cell protection mechanisms within and outside the cell membrane. These biological activities are better explained during the application of such IONPs in drug delivery systems, cancer cell eradication, and other biomedical-related processes as discussed in detail in the upcoming section.

Applications of synthesized iron oxide nanoparticles

Nanomaterials are created on purpose by chemical reactions or physical actions using engineering techniques, and they exhibit unique physical and chemical properties. They are used in engineering, biology, pharmacology, and environmental remediation. Table 1 contains examples of IONPs and composite-based IONPs used for various engineering and medicinal applications. Regardless of the numerous uses of synthesized IONPs, such as plant and tissue remediation, biomedical treatments, pharmaceutics and drug delivery systems, and wastewater treatment, it is essential to recognize that the need for nanomaterials cannot be overstated. Thus, the part that follows describes in detail the endeavors and achievements of researchers regarding the applicability of IONPs in engineering, biology, pharmacology, and environmental remediation procedures.

Remedy for bone repair and tissue degradation

IONPs are useful in tissue engineering and cell regeneration, as well as in horticulture and cancer patient treatment for plants and humans, respectively. However, additional research on IONPs' duration, size precision, and magnetic field intensity is necessary before their application in gene protein acceleration for bone tissue regeneration and skill remediation. IONPs' repair capabilities and application in horticulture and cancer patient treatment for plants and humans, respectively, are among their numerous advantageous applications [ 209 ]. Fathi-Achachelouei et al. [ 210 ] provided an overview of iron oxide nanoparticles' applications in tissue engineering and regenerative medicine. Recent breakthroughs in the application of IONPs in convection-based medicinal practices have centered on the use of nanomaterials to monitor skin-related harm in therapeutic medicine [ 211 ], cancer therapy [ 212 ], and cell regeneration [ 213 ]. Yet, the translation of synthesized IONPs into clinical medicine applications continues to be plagued by numerous obstacles. This issue mostly includes toxicity investigations on IONPs, which are crucial for clinical translation [ 214 ]. In practice, multi-parameter labeling and inadequate handling of nanomaterials may hinder their clinical transferability for tissue engineering and cell regeneration [ 215 ]. Consequently, the successful translation of clinical medicine must involve an in vivo and in vitro toxicological process before the bio-distribution of IONPs in the injured tissue. Bone tissue restoration is another biomedical application of IONPs, as IONPs, with their non-toxicity and good magnetic and semi-conducting properties, are extraordinarily useful for tissue repair [ 216 ]. The IONPs are integrated into stem cells, which strengthen the muscle fibers surrounding the bones of affected individuals [ 217 ]. Using magnetic action, this combination increases the materialization process of the protein fiber surrounding the afflicted bone area [ 218 ]. Before its application in gene protein acceleration for bone tissue regeneration and skill remediation, however, additional research on the IONP's duration, size precision, and magnetic field intensity is necessary.

Drug delivery systems and cancer treatment

Superparamagnetic IONPs are employed in medicine delivery systems via magnetic resonance analysis and are also used in radiology and pharmaceutical medicine via MRI to treat cancer. Numerous publications have examined the biocompatibility applications of superparamagnetic IONPs and their use in clinical and diagnostic medicine [ 219 ]. The use of synthetic magnetic IONPs in drug delivery systems relies on the magnetic resonance analysis concept, in which the action of molecular medicine transports the nanoparticles to the precise location of damaged tissues. Thus, the migration of medications into the afflicted tissue does not necessarily impact the magnetic characteristics of the IONP. In addition, multifunctional IONPs can be used in imaging and drug delivery systems for prostate cancer, and they also have applications in breast cancer medicine delivery systems. Gutierrez et al. [ 220 ] investigate the use of such IONPs in MRI and drug delivery systems for prostate cancer. The process is referred to as the double-receptor targeting method, which suggests an alternative to chemotherapy for prostate cancer. By targeting nanoparticle therapy at the damaged region, harmful chemicals delivered by anticancer drugs into cells and tissues are decreased. This approach also has the disadvantages of being expensive, time-consuming, difficult to use, and requiring multiple clinical investigations on the IONPs before usage. Before using IONPs in any form for drug delivery or medicinal applications, the magnetic characteristics must be understood. Failing to determine the magnetic sensitivity of IONPs can result in clinical failure. The most significant benefit of the magnetically sensitive nature of IONPs over convectional physical methods is their versatility of application in drug delivery domains due to their simplicity, low cost, and shortened incubation time [ 221 ]. Magnetic IONPs also have applications in breast cancer medicine delivery systems [ 222 ]. In this method, pure maghemite (γ-Fe 2 O 3 ) is substituted with magnetite NPs, which may produce harmful radicals that degrade into health concerns [ 223 ]. Consequently, the growing interest in magnetic nanoparticles (γ-Fe 2 O 3 ) as an alternative to magnetite IONP is minimizing the risk of generating hazardous Fe (II) ion radicals on the surface of malignant breast tissue. However, a comprehensive biocompatibility process must be executed on the various types of IONPs for drug delivery and cancer treatment [ 224 ] for applications in biomedicine.

Waste water and environmental remediation

The importance of nanomaterial synthesis, characterization, and application research cannot be overstated. The applications of IONPs are most prominent in wastewater treatment, environmental remediation, pollution prevention, and the sensing and detention of foreign bodies in water bodies purification, environmental remediation, pollution prevention, and the sensing and detention of foreign bodies in the waterways [ 225 ]. In terms of nanotechnology, water purification involves the removal of pollutants and the treatment of wastewater [ 226 ]. Hence, despite the advancements made in nanotechnology for environmental science and wastewater purification, there is a need for a scientific study aimed at the discovery of high-precision nanomaterials and nanotechnological processes [ 227 ]. The nanofiltration technique is the principal technological method for wastewater treatment [ 228 ], and it uses membrane filtration to remove numerous pollutants. Magnetic IONPs are used in wastewater treatment to neutralize extremely alkaline groundwater. This approach offers a high level of water purification by removing numerous pollutants [ 227 ]. Also, the approach is effective for treating solid waste [ 229 ], pathogens [ 230 ], monovalent and divalent compounds [ 231 ], and wastewater [ 232 ].

Powell, et al. [ 233 ] utilized IONPs for the treatment of treated wastewater in underflow situations via a magnetic nanoparticle device (MagNERD). The method employs superparamagnetic magnetite that was created, collected, and isolated from improved MagNERD.

Magnetic γ-Fe 2 O 3 IONPs are utilized by Shipley et al. [ 70 ] for the remediation of subsurface soil and groundwater. The low PH value (3–5) of IONPs was utilized to neutralize extremely alkaline groundwater. This method is the standard wastewater treatment and soil remediation method that has been optimized [ 234 , 235 , 236 ]. Nonetheless, significant technological improvements have been documented in the exploitation, implementation, and application of IONPs in wastewater treatment [ 237 , 238 , 239 ]. Due to their strong reactivity, tiny sizes, and outstanding surface functionality, IONPs perform very well as absorbents in wastewater treatment, according to the vast majority of nanomaterials research [ 240 , 241 ]. This development in the use of IONPs for waste remediation is based on their participation in magnetic particle generation, flocculation, and ionic and bio-separation processes [ 242 , 243 ]. The major limitations of IONP application for wastewater and environmental remediation are largely attributable to poor regeneration and reuse of the synthesized IONPs, lack of engagement of IONPs in green technology research, and increased treatment water filtration, modification of biosynthesized materials extraction due to their non-biodegradable nature, and increased treatment water filtration due to the highly insoluble nature of the ionized iron hydroxide (FeOOH) nanoparticle [ 244 , 245 , 246 ]. Thus, the development of IONPs for water purification, environmental remediation, and biomedical applications remains crucial for the growth of applications of metallic nanofabricated materials for human health and future nanotechnology trends and advances.

Conclusion and future perspectives

This work examined how IONPs are manufactured and how they might be utilized in biomedicine, wastewater treatment, and environmental cleanup, among other domains. The paper provided an up-to-date examination of the synthesis, characterization, and application methodologies for iron oxide nanoparticles, as well as new developments in nanofabrication and applications. The literature review supports the numerous iron oxide categories, such as maghemite, hematite, and magnetite, and their preparation processes (i.e., mechanical milling, lithography, thermal decomposition, mechanochemical, co-precipitation method, etc.). This is the conclusion of the study:

Important factors for the synthesis, characterization, and application of iron oxide nanoparticles include, but are not limited to, nanoparticle sizes, shapes, magnetic properties, and surface functioning. Because the aforementioned parameters are the consequential catalytic activity, microstructure phase, and crystallinity of IONPs, nanotechnology has been demonstrated to be useful and necessary in areas such as wastewater treatment, the creation of superparamagnetic devices, drug delivery, and biomedical applications.

With the development of sophisticated research and methods in the field of green technology for the manufacture of nanomaterials and nanocomposites, the difficulties and hazards connected with nano-processing iron oxides can be reduced.

The study explains the dependability of IONPs as regards human and environmental concerns cannot be overstated. Using nanofabrication processes to produce innovative engineering materials can be energy-, time-consuming, and capital-intensive.

The superparamagnetic properties of IONPs (magnetite and maghemite) have encouraged their suitability in diverse areas of applications, including plant development, biomedicine, drug delivery, cancer cell eradication, and environmental pollutants. These interesting magnetization properties are enshrined in biocompatibility, being low toxicity, environmentally friendly, less time-consuming, and having high biomedicine and pharmaceutical tendencies.

The promising future of treatment of diseases, microbial pathogens, and cancer cell eradication through the introduction of green synthesized IONPs for drug delivery purposes remains a key aspect of the application of the nanofabrication process. Also, IONPs can be used as an alternative remedy for persistent dye removal from soils and the eradication of environmental pollutants.

It is important to note that the choice between biological and physicochemical approaches for IONP synthesis is determined by the application's specific requirements. While biological approaches have numerous advantages, physicochemical methods may be preferred in some situations, such as when precise control over nanoparticle properties or specific surface coatings is required. Cost, scalability, and the intended usage of the nanoparticles should all be considered.

For future studies, the synthesis of iron oxide nanoparticles using environmentally friendly technology has numerous advantages, but it is important to conduct a comparative investigation of IONPs created via green fabrication. In terms of their reactivity, particle stability, phase microstructure, and bio-toxicology features, it is necessary to conduct a comparative investigation of iron oxide nanoparticles created via green fabrication.

The methods of synthesis, characterization, and applications of IONPs and IONP-based composites, which include AuNPs, MIONPs, Fe 3 O 4 @AuNP, nZVI, and SFMIONPs, were discussed in this paper.

In addition, the risk evaluation of particle aggregation, material dissolution, and kinetics of synthetic iron oxide nanoparticles must be used to provide a solid foundation for functionalized applications of synthesized IONPs made using the green engineering method.

Data availability

Raw data is available upon request from the corresponding author.

Code availability

Source code is available upon request from the corresponding author.

Abbreviations

Gold nanoparticles

Energy-dispersive spectroscopy

Dimethyl sulfoxide

High-resolution transmission electron microscope

Fourier transform infrared

Magnetic resonance Imaging

Nanoparticles

Iron oxide-coated gold nanoparticles

• Iron oxide nanoparticles

Magnetite nanoparticles

Magnetic iron oxide nanoparticles

Nanoscale zero-valent iron

Scanning electron microscope

Surface-functionalized magnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles

Transmission electron microscope

Tri-butyl phosphate

Thermogravimetric analysis

Thermogravimetric/thermal differential analysis

Tri-octyl phosphine oxide

X-ray absorption spectroscopy technique

X-ray diffraction

X-ray fluorescence

Zero-valent metallic iron

Gopal SV, Mini R, Jothy VB, Joe IH. Synthesis and characterization of Iron oxide nanoparticles using DMSO as a stabilizer. Mater Today: Proc. 2015;2(3):1051–5. https://doi.org/10.1016/j.matpr.2015.06.036 .

Article   Google Scholar  

Rivas-Sánchez ML, Alva-Valdivia LM, Arenas-Alatorre J, Urrutia-Fucugauchi J, Perrin M, Goguitchaichvili A, Molina MAR. Natural magnetite nanoparticles from an iron-ore deposit: size dependence on magnetic properties. Earth, Planets Space. 2009;61(1):151–60. https://doi.org/10.1186/bf03352895 .

Sebehanie KG, del Rosario AV, Ali AY, Femi OE. Production of magnetite nanoparticles from Ethiopian iron ore using solvent extraction and studying parameters that affect crystallite size. Mater Res Express. 2020. https://doi.org/10.1088/2053-1591/abc2df .

Wierzbinski KR, Szymanski T, Rozwadowska N, Rybka JD, Zimna A, Zalewski T, Kurpisz MK. Potential use of superparamagnetic iron oxide nanoparticles for in vitro and in vivo bioimaging of human myoblasts. Sci Rep. 2018. https://doi.org/10.1038/s41598-018-22018-0 .

Li J, Shi X, Shen M. Hydrothermal synthesis and functionalization of iron oxide nanoparticles for MR imaging applications. Part Part Syst Charact. 2014;31(12):1223–37. https://doi.org/10.1002/ppsc.201400087 .

Article   CAS   Google Scholar  

Wu J-H, Ko SP, Liu H-L, Kim S, Ju J-S, Kim YK. Sub 5 nm magnetite nanoparticles: synthesis, microstructure, and magnetic properties. Mater Lett. 2007;61(14–15):3124–9. https://doi.org/10.1016/j.matlet.2006.11.032 .

Reich M, Utsunomiya S, Kesler SE, Wang L, Ewing RC, Becker U. Thermal behaviour of metal nanoparticles in geologic materials. Geology. 2006;34(12):1033. https://doi.org/10.1130/g22829a.1 .

Frandsen C, Mørup S. Reversible aggregation and magnetic coupling of α-Fe 2 O 3 nanoparticles. J Phys: Condens Matter. 2006;18(31):7079–84. https://doi.org/10.1088/0953-8984/18/31/003 .

Lu A-H, Salabas EL, Schüth F. Magnetic nanoparticles: synthesis, protection, functionalization, and application. Angew Chem Int Ed. 2007;46(8):1222–44. https://doi.org/10.1002/anie.200602866 .

Yang H-H, Zhang SQ, Chen XL, Zhuang ZX, Xu JG, Wang XR. Magnetite-containing spherical silica nanoparticles for biocatalysis and bioseparations. Anal Chem. 2004;76(5):1316–21. https://doi.org/10.1021/ac034920m .

Wu S, Sun A, Zhai F, Wang J, Xu W, Zhang Q, Volinsky AA. Fe 3 O 4 magnetic nanoparticles synthesis from tailings by ultrasonic chemical co-precipitation. Mater Lett. 2011;65(12):1882–4. https://doi.org/10.1016/j.matlet.2011.03.065 .

Lee B, Koo S. Preparation of silver nanoparticles on the surface of fine magnetite particles by a chemical reduction. J Ind Eng Chem. 2011;17(4):762–6. https://doi.org/10.1016/j.jiec.2011.05.030 .

Lian S, Wang E, Kang Z, Bai Y, Gao L, Jiang M, Xu L. Synthesis of magnetite nanorods and porous hematite nanorods. Solid State Commun. 2004;129(8):485–90. https://doi.org/10.1016/j.ssc.2003.11.043 .

Darezereshki E, Khodadadi Darban A, Abdollahy M. Synthesis of magnetite nanoparticles from iron ore tailings using a novel reduction-precipitation method. J Alloy Compounds. 2018;15(749):336–43. https://doi.org/10.1016/j.jallcom.2018.03.278 .

Suh YJ, Do MT, Kil DS, Jang HD, Cho K. Production of high-purity magnetite nanoparticles from a low-grade iron ore via solvent extraction. Korean Chem Eng Res. 2015;53(1):39–45. https://doi.org/10.9713/kcer.2015.53.1.39 .

Pérez N, López-Calahorra F, Labarta A, Batlle X. Reduction of iron by decarboxylation in the formation of magnetite nanoparticles. Phys Chem Chem Phys. 2011;13(43):19485. https://doi.org/10.1039/c1cp20457b .

Cho D-W, Song H, Schwartz FW, Kim B, Jeon BH. The role of magnetite nanoparticles in the reduction of nitrate in groundwater by zero-valent iron. Chemosphere. 2015;125:41–9. https://doi.org/10.1016/j.chemosphere.2015.01 .

Zhu K, Ju Y, Xu J, Yang Z, Gao S, Hou Y. Magnetic nanomaterials: chemical design, synthesis, and potential applications. Acc Chem Res. 2018;51(2):404–13. https://doi.org/10.1021/acs.accounts.7b00407 .

Marciello M, Luengo Y, Morales MP. Iron oxide nanoparticles for cancer diagnosis and therapy. Nanoarchitectonics Smart Deliv Drug Target. 2016. https://doi.org/10.1016/b978-0-323-47347-7.00024-0 .

Lu S, Sun Y, Chen C. Adsorption of radionuclides on carbon-based nanomaterials. Emerging Nat Tailored Nanomater Radioact Waste Treat Environ Remediation - Princ Methodol. 2019. https://doi.org/10.1016/b978-0-08-102727-1.00004-2 .

Soshnikova Y, Omelchenko A, Shekhter A, Sobol E. Magnetite nanoparticles for diagnostics and laser repair of cartilage. Nanobiomater Hard Tissue Eng. 2016. https://doi.org/10.1016/b978-0-323-42862-0.00015-8 .

Epherre R, Goglio G, Mornet S, Duguet E. Hybrid magnetic nanoparticles for targeted delivery. Compr Biomater. 2011. https://doi.org/10.1016/b978-0-08-055294-1.00145-8 .

Takai ZI, Mustafa MK, Asman S. Synthesis and characterization of magnetite (Fe 3 O 4 ) nanoparticles with different levels of aniline dimer-COOH by Co-precipitation method. Nanosci Nanotech: Nano-SciTech. 2019. https://doi.org/10.1063/1.5124670 .

Unni M, Uhl AM, Savliwala S, Savitzky BH, Dhavalikar R, Garraud N, Lena F, Andrew JS, Rinaldi CR. Thermal decomposition synthesis of iron oxide nanoparticles with diminished magnetic dead layer by controlled addition of oxygen. ACS Nano. 2017;11(2):2284–303. https://doi.org/10.1021/acsnano.7b00609 .

Huelser TP, Wiggers H, Ifeacho P, Dmitrieva O, Dumpich G, Lorke A. Morphology, structure and electrical properties of iron nanochains. Nanotechnology. 2006;17(13):3111–5. https://doi.org/10.1088/0957-4484/17/13/005 .

Saif S, Tahir A, Chen Y. Green synthesis of iron nanoparticles and their environmental applications and implications. Nanomaterials. 2016;6(11):209. https://doi.org/10.3390/nano6110209 .

Natarajan S, Harini K, Gajula GP, Sarmento B, Neves-Petersen MT, Thiagarajan V. Multifunctional magnetic iron oxide nanoparticles: diverse synthetic approaches, surface modifications, cytotoxicity towards biomedical and industrial applications. BMC Materials. 2019. https://doi.org/10.1186/s42833-019-0002-6 .

Rosen JE, Chan L, Shieh DB, Gu FX. Iron oxide nanoparticles for targeted cancer imaging and diagnostics. Nanomed Nanotech Biol Med. 2012;8(3):275–90. https://doi.org/10.1016/j.nano.2011.08.017 .

Kolhatkar A, Jamison A, Litvinov D, Willson R, Lee T. Tuning the magnetic properties of nanoparticles. Int J Mol Sci. 2013;14(8):15977–6009. https://doi.org/10.3390/ijms140815977 .

Khan I, Saeed K, Khan I. Nanoparticles: properties, applications and toxicities. Arab J Chem. 2017. https://doi.org/10.1016/j.arabjc.2017.05.011 .

Jalil Z, Rahwanto A, Mulana F, Handoko E. Synthesis of nano-hematite (Fe 2 O 3 ) extracted from natural iron ore prepared by the mechanical alloying method. Nanosci Nanotech: Nano-Scitech. 2019. https://doi.org/10.1063/1.5124671 .

Ganapathe LS, Mohamed MA, Mohamad Yunus R, Berhanuddin DD. Magnetite (Fe 3 O 4 ) nanoparticles in biomedical application: from synthesis to surface functionalisation. Magnetochemistry. 2020;6(4):68. https://doi.org/10.3390/magnetochemistry60400 .

Ali A, Zafar H, Zia M, Haq I, Phull AR, Ali JS, Hussain A. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles. Nanotechnol Sci Appl. 2016;9:49–67. https://doi.org/10.2147/nsa.s99986 .

Petrovský S, Holliger N, Pfromm PH, Liu B, Chikan V. Size-controlled synthesis of iron and iron oxide nanoparticles by the rapid inductive heating method. ACS Omega. 2020. https://doi.org/10.1021/acsomega.0c02793 .

Singh K, Raman RK. Mechanical alloying of elemental powders into nanocrystalline (NC) Fe-Cr alloys: remarkable oxidation resistance of NC alloys. MPDI Metals. 2021;46(11):695. https://doi.org/10.3390/met11050695 .

Mohapatra M, Anand S. Synthesis and applications of nano-structured iron oxides/hydroxides – a review. Int J Eng Sci Technol. 2011. https://doi.org/10.4314/ijest.v2i8.63846 .

Irfan I, Ezaz G, Ammara N, Aysha B. Detail review on chemical, physical and green synthesis, classification, characterizations and applications of nanoparticles. Green Chem Lett Rev. 2020;13(3):59–81. https://doi.org/10.1080/17518253.2020.1802517 .

Guo D, Xie G, Luo J. Mechanical properties of nanoparticles: basics and applications. J Phys D: Appl Phys. 2013;47(1):013001. https://doi.org/10.1088/0022-3727/47/1/013001 .

Satyanarayana T, Reddy TS. A review on chemical and physical synthesis methods of nanomaterials. Int J Res Appl Sci Eng Technol. 2018;13(3):59–81.

Google Scholar  

Ali A, Zafar H, Zia M, Haq I, Phull AR, Ali JS, Hussain A. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles. Nanotech, Sci Appl. 2016;9:49–67. https://doi.org/10.2147/nsa.s99986 .

Samrot AV, Sahithya CS, Selvarani AJ, Purayil SK, Ponnaiah P. A review on synthesis characterization and potential biological applications of superparamagnetic iron oxide nanoparticles. Curr Res Green Sustain Chem. 2020. https://doi.org/10.1016/j.crgsc.2020.100042 .

Wu W, He Q, Jiang C. Magnetic iron oxide nanoparticles: synthesis and surface functionalization strategies. Nanoscale Res Lett. 2008;3(11):397–415. https://doi.org/10.1007/s11671-008-9174-9 .

Dobson J. Magnetic nanoparticles for drug delivery. Drug Dev Res. 2006;67(1):55–60. https://doi.org/10.1002/ddr.20067 .

Wu W, Wu Z, Yu T, Jiang C, Kim W-S. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications. Sci Technol Adv Mater. 2015;16(2):023501. https://doi.org/10.1088/1468-6996/16/2/023501 .

Xu P, Zeng GM, Huang DL, Feng CL, Hu S, Zhao MH, Lai C, Wei Z, Huang C, Xie GX, Liu ZF. Use of iron oxide nanomaterials in wastewater treatment: a review. Sci Total Environ. 2012;424:1–10. https://doi.org/10.1016/j.scitotenv.2012.02 .

Gul S, Khan SB, Rehman IU, Khan MA, Khan MI. A comprehensive review of magnetic nanomaterials modern day theranostics. Front Mater. 2019. https://doi.org/10.3389/fmats.2019.00179 .

Dheyab MA, Aziz AA, Jameel MS. Recent advances in inorganic nanomaterials synthesis using sonochemistry: a comprehensive review on iron oxide, gold and iron oxide coated gold nanoparticles. Molecules. 2021;26:2453. https://doi.org/10.3390/molecules26092453 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Potential of a sonochemical approach to generate MRI-PPT theranostic agents for breast cancer. Photodiagnosis Photodyn Ther. 2021;33:102177. https://doi.org/10.1016/j.pdpdt.2021.102177 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Excellent relaxivity and X-ray attenuation combo properties of Fe 3 O 4 @Au CSNPs produced via Rapid sonochemical synthesis for MRI and CT imaging. Mater Today Commun. 2020;25:101368. https://doi.org/10.1016/j.mtcomm.2020.10136 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Gold-coated iron oxide nanoparticles as a potential photothermal therapy agent to enhance eradication of breast cancer cells. J Phys Conf Ser. 2020;1497:102003. https://doi.org/10.1088/1742-6596/1497/1/012003 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Simple rapid stabilization method through citric acid modification for magnetite nanoparticles. Sci Rep. 2020;10(1):10793. https://doi.org/10.1038/s41598-020-67869-8 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Mechanisms of effective gold shell on Fe 3 O 4 core nanoparticles formation using sonochemistry method. Ultrasonics Sonochem. 2020. https://doi.org/10.1016/j.ultsonch.2019.104865 .

Dheyab MA, Aziz AA, Jameel MS. Synthesis and optimization of the sonochemical method for functionalizing gold shell on Fe 3 O 4 core nanoparticles using response surface methodology. Surf Interfaces. 2020;21:100647. https://doi.org/10.1016/j.surfin.2020.100647 .

Dheyab MA, Aziz AA, Jameel MS, Noqta OA, Khaniabadi PM, Mehrdel B. Synthesis and coating methods of biocompatible iron oxide/gold nanoparticle and nanocomposite for biomedical applications. Chin J Phys. 2020;64:305–25. https://doi.org/10.1016/j.cjph.2019.11.014 .

Kheshtzar R, Berenjian A, Taghizadeh S-M, Ghasemi Y, Asad AG, Ebrahiminezhad A. Optimization of reaction parameters for the green synthesis of zero-valent iron nanoparticles using pine tree needles. Green Process Synth. 2019;8(1):846–55. https://doi.org/10.1515/gps-2019-0055 .

Choi WI, Kim J-Y, Heo SU, Jeong YY, Kim YH, Tae G. The effect of mechanical properties of iron oxide nanoparticle-loaded functional nano-carrier on tumour targeting and imaging. J Control Release. 2012;162(2):267–75. https://doi.org/10.1016/j.jconrel.2012.07.020 .

Seabra AB, Pelegrino MT, Haddad PS. Antimicrobial applications of superparamagnetic iron oxide nanoparticles. Nanostruct Antimicrob Ther. 2017. https://doi.org/10.1016/b978-0-323-46152-8.00024-x .

Andrade RGD, Veloso SRS, Castanheira EMS. Shape anisotropic iron oxide-based magnetic nanoparticles: synthesis and biomedical applications. Int J Mol Sci. 2020;21(7):2455. https://doi.org/10.3390/ijms21072455 .

Luo S, Ma C, Zhu M-Q, Ju W-N, Yang Y, Wang X. Application of iron oxide nanoparticles in the diagnosis and treatment of neurodegenerative diseases with emphasis on Alzheimer’s disease. Front Cell Neurosci. 2020. https://doi.org/10.3389/fncel.2020.00021 .

Friedrich RP, Cicha I, Alexiou C. Iron oxide nanoparticles in regenerative medicine and tissue engineering. Nanomaterials. 2021;11:2337. https://doi.org/10.3390/nano11092337 .

Lu D, Wu X, Wang W, Ma C, Pei B, Wu S. Synthesis and application of iron oxide nanoparticles in bone tissue repair. J Nanomater. 2021. https://doi.org/10.1155/2021/3762490 .

Cortajarena AL, Ortega D, Ocampo SM, Gonzalez-García A, Couleaud P, Miranda R, Ayuso-Sacido A. Engineering iron oxide nanoparticles for clinical settings. Nanobiomedicine. 2014;1:2. https://doi.org/10.5772/58841 .

Couto D, Freitas M, Carvalho F, Fernandes E. Iron oxide nanoparticles: an insight into their biomedical applications. Curr Med Chem. 2015;22:1808–28. https://doi.org/10.2174/0929867322666150311151403 .

Maharramov AM, Alieva IN, Abbasova GD, Ramazanov MA, Nabiyev NS, Saboktakina MR. Iron oxide nanoparticles in drug delivery systems. Dig J Nanomater Biostruct. 2011;6(2):419–31.

Ahmed MS, Bin Salam A, Yates C, Willian K, Jaynes J, Turner T, Abdalla M. Double-receptor-targeting multifunctional iron oxide nanoparticles drug delivery system for the treatment and imaging of prostate cancer. Int J Nanomed. 2017;12:6973–84. https://doi.org/10.2147/ijn.s139011 .

Ovid’ko IA, and Pande CS and Masumura RA,. Grain boundaries in nanomaterials. Taylor Francis. 2006. https://doi.org/10.1201/9781420004014.ch18 .

Afshari V, Dehghanian C. The influence of grain size of pure iron metal on corrosion inhibition in presence of sodium nitrite. Int J Mod Phys Conf Ser. 2012;05:793–800. https://doi.org/10.1142/s2010194512002760 .

Marcu A, Pop S, Dumitrache F, Mocanu M, Niculite CM, Gherghiceanu M, Morjan I. Magnetic iron oxide nanoparticles as drug delivery system in breast cancer. Appl Surf Sci. 2013;281:60–5. https://doi.org/10.1016/j.apsusc.2013.02.072 .

Kumar P, Agnihotri S, Roy I. Preparation and characterization of superparamagnetic iron oxide nanoparticles for magnetically guided drug delivery. Int J Nanomed. 2018;13:43–6. https://doi.org/10.2147/ijn.s125002 .

Powell CD, Atkinson AJ, Ma Y, Marcos-Hernandez M, Villagran D, Westerhoff P, Wong MS. Magnetic nanoparticle recovery device (MagNERD) enables application of iron oxide nanoparticles for water treatment. J Nanopart Res. 2020. https://doi.org/10.1007/s11051-020-4770-4 .

Ahmad NS, Radiman S, Yaacob WZ. Stability and transportation of iron oxide nanoparticles in subsurface water and soil. ASM Sci J. 2021;14:1–9. https://doi.org/10.32802/asmscj.2020.488 .

Aragaw TA, Bogale FM, Aragaw BA. Iron-based nanoparticles in wastewater treatment: a review on synthesis methods, applications, and removal mechanisms. J Saudi Chem Soc. 2021;25(8):101280. https://doi.org/10.1016/j.jscs.2021.101280 .

Santhosh C, Malathi A, Dhaneshvar E, Bhatnagar A, Grace AN, Madhavan J. Iron oxide nanomaterials for water purification. Nanoscale Mater Water Purif. 2019. https://doi.org/10.1016/b978-0-12-813926-4.00022-7 .

Subha V, Divya K, Gayathri S, et al. Applications of iron oxide nanocomposite in wastewater treatment–dye decolourisation and antimicrobial activity. MOJ Drug Des Develop Ther. 2018;2(5):178–84. https://doi.org/10.15406/mojddt.2018.02.00058 .

Tiwari DK, Behari J, Sen P. Application of nanoparticles in waste water treatment. World Appl Sci J. 2008;3(3):417–33.

Singh S, Kumar V, Romero R, Sharma K, Singh J. Applications of nanoparticles in wastewater treatment. In: Prasad R, Kumar V, Kumar M, Choudhary D, editors. Nanobiotechnology in bioformulations. Springer, Cham: Nanotechnology in the Life Sciences; 2019.

Krispin M, Ullrich A, Horn S. Crystal structure of iron-oxide nanoparticles synthesized from ferritin. J Nanopart Res. 2012;14(2):1–11. https://doi.org/10.1007/s11051-011-0669-4 .

Ismail I, Balachandran S, Devi MG. Synthesis, characterization and application of nanoparticles in wastewater treatment. Indian Chem Eng. 2018. https://doi.org/10.1080/00194506.2018.1469099 .

Zelić E, Vuković Z, Halkijević I. Application of nanotechnology in wastewater treatment. J Croatian Assoc Civil Eng. 2018;70(04):315–23. https://doi.org/10.14256/jce.2165.2017 .

Mai TN, Tetsu Y. Sputtering onto a liquid: interesting physical preparation method for multi-metallic nanoparticles. Sci Technol Adv Mater. 2018;19:883–98. https://doi.org/10.1080/14686996.2018.1542926 .

Nie M, Sun K, Meng DD. Formation of metal nanoparticles by short-distance sputters deposition in a reactive ion etching chamber. J Appl Phys. 2009;106(5):054314. https://doi.org/10.1063/1.3211326 .

Acsente T, Gabriela Carpen L, Matei E, Bita B, Negrea R, Bernard E, Dinescu G. Tungsten nanoparticles produced by magnetron sputtering gas aggregation: process characterization and particle properties. Progress Fine Part Plasmas. 2020. https://doi.org/10.5772/intechopen.91733 .

Nakagawa K, Narushima T, Udagawa S, Yonezawa T. Preparation of copper nanoparticles in liquid by matrix sputtering process. J Phys Conf Ser. 2013;417:012038. https://doi.org/10.1088/1742-6596/417/1/012038 .

Aubry E, Liu T, Dekens A, Perry F, Mangin S, Hauet T, Billard A. Synthesis of iron oxide films by reactive magnetron sputtering assisted by plasma emission monitoring. Mater Chem Phys. 2019;223:360–5. https://doi.org/10.1016/j.matchemphys.2018.11 .

Kumpika T, Ruˇcman S, Polin S, Kantarak E, Sroila W, Thongsuwan W, Panthawan A, Sanmuangmoon P, Jhuntama N, Singjai P. Studies on the characteristics of nanostructures produced by sparking discharge process in the ambient atmosphere for air filtration application. Crystals. 2021;11:140. https://doi.org/10.3390/cryst11020140 .

Drmota A, Drofenik M, Koselj J, Nidari A. Microemulsion method for synthesis of magnetic oxide nanoparticles. Microemulsions - Introduction Properties Appl. 2012. https://doi.org/10.5772/36154 .

Mitar I, Guć L, Soldin Ž, Vrankić M, Paut A, Prkić A, Krehula S. Rapid microwave method for synthesis of iron oxide particles under specific conditions. Crystals. 2021;11(4):383. https://doi.org/10.3390/cryst11040383 .

Rivera-Chaverra MJ, Restrepo-Parra E, Acosta-Medina CD, Mello A, Ospina R. Synthesis of oxide iron nanoparticles using laser ablation for possible hyperthermia applications. Nanomaterials. 2020;10(11):2099. https://doi.org/10.3390/nano10112099 .

Sathya K, Saravanathamizhan R, Baskar G. Ultrasound-assisted photosynthesis of iron oxide nanoparticles. Ultrason Sonochem. 2017;39:446–51. https://doi.org/10.1016/j.ultsonch.2017.05.01 .

Masthoff I-C, Kraken M, Menzel D, Litterst FJ, Garnweitner G. Study of the growth of hydrophilic iron oxide nanoparticles obtained via the non-aqueous sol-gel method. J Sol-Gel Sci Technol. 2015;77(3):553–64. https://doi.org/10.1007/s10971-015-3883-1 .

Wen D, Song P, Zhang K, Qian J. Thermal oxidation of iron nanoparticles and its implication for chemical-looping combustion. J Chem Technol Biotechnol. 2010;86(3):375–80. https://doi.org/10.1002/jctb.2526 .

Suryanarayana C. Synthesis of nanocomposites by mechanical alloying. J Alloy Compd. 2011;509:S229–34. https://doi.org/10.1016/j.jallcom.2010.09.063 .

Olekšáková D, Kollár P, Füzer J, Kusý M, Roth S, Polanski K. The influence of mechanical milling on the structure and soft magnetic properties of NiFe and NiFeMo alloys. J Magn Magn Mater. 2007;316(2):e838–41. https://doi.org/10.1016/j.jmmm.2007.03.111 .

Tulinski M, Jurczyk M. Nanomaterials synthesis methods. Metrol Standardization Nanotech Protoc Indus Innov. 2017;15:75–98.

Glasgow W, Fellows B, Qi B, Darroudi T, Kitchens C, Ye L, Mefford OT. Continuous synthesis of iron oxide (Fe 3 O 4 ) nanoparticles via thermal decomposition. Particuology. 2016;26:47–53. https://doi.org/10.1016/j.partic.2015.09.011 .

Dixit S, Jeevanandam P. Synthesis of iron oxide nanoparticles by thermal decomposition approach. Adv Mater Res. 2009;67:221–6. https://doi.org/10.4028/www.scientific.net/am .

Chen Z. Size and shape controllable synthesis of monodisperse iron oxide nanoparticles by thermal decomposition of iron oleate complex. Synth React Inorg, Met-Org, Nano-Met Chem. 2012;42(7):1040–6. https://doi.org/10.1080/15533174.2012.680126 .

Amara D, Margel S. Synthesis and characterization of elemental iron and iron oxide nano/micro composite particles by thermal decomposition of ferrocene. Nanotechnol Rev. 2013. https://doi.org/10.1515/ntrev-2012-0061 .

Toyos-Rodríguez C, Calleja-García J, Torres-Sánchez L, López A, Abu-Dief AM, Costa A, Elbaile L, Crespo RD, Garitaonandia JS, Lastra E, García JA, García-Alonso FJ. A simple and reliable synthesis of superparamagnetic magnetite nanoparticles by thermal decomposition of Fe(acac) 3 . J Nanomater. 2019. https://doi.org/10.1155/2019/2464010 .

Maity D, Kale SN, Kaul-Ghanekar R, Xue J-M, Ding J. Studies of magnetite nanoparticles synthesized by thermal decomposition of iron (III) acetylacetonate in tri(ethylene glycol). J Magn Magn Mater. 2009;321(19):3093–8. https://doi.org/10.1016/j.jmmm.2009.05.020 .

Vorozhtsov S, Zhukov I, Vorozhtsov A, Zhukov A, Eskin D, Kvetinskaya A. Synthesis of micro- and nanoparticles of metal oxides and their application for reinforcement of Al-based alloys. Adv Mater Sci Eng. 2015. https://doi.org/10.1155/2015/718207 .

Mazrouaa AM, Mohamed MG, Fekry M. Physical and magnetic properties of iron oxide nanoparticles with different molar ratio of ferrous and ferric. Egypt J Pet. 2019. https://doi.org/10.1016/j.ejpe.2019.02.002 .

Colson P, Henrist C, Cloots R. Nanosphere lithography: a powerful method for the controlled manufacturing of nanomaterials. J Nanomater. 2013;2013:1–19. https://doi.org/10.1155/2013/948510 .

Lee JS, Hill RT, Chilkoti A, Murphy WL. Surface patterning. Biomater Sci. 2020. https://doi.org/10.1016/b978-0-12-816137-1.00037-4 .

Lassenberger A, Grünewald TA, van Oostrum PDJ, Rennhofer H, Amenitsch H, Zirbs R, Reimhult E. Monodisperse iron oxide nanoparticles by thermal decomposition: elucidating particle formation by second-resolved in situ small-angle X-ray scattering. Chem Mater. 2017;29(10):4511–22. https://doi.org/10.1021/acs.chemmater.7b01207 .

Martins PM, Lima AC, Ribeiro S, Lanceros-Mendez S, Martins P. Magnetic nanoparticles for biomedical applications: from the soul of the earth to the deep history of ourselves. ACS Appl Bio Mater. 2021;4(8):5839–70. https://doi.org/10.1021/acsabm.1c00440 .

Iqbal A, Iqbal K, Li B, Gong D, Qin W. Recent advances in iron nanoparticles: preparation, properties, biological and environmental application. J Nanosci Nanotechnol. 2017;17(7):4386–409. https://doi.org/10.1166/jnn.2017.14196 .

Issa B, Obaidat I, Albiss B, Haik Y. Magnetic nanoparticles: surface effects and properties related to biomedicine applications. Int J Mol Sci. 2013;14(11):21266–305. https://doi.org/10.3390/ijms141121266 .

Baaziz W, Pichon BP, Fleutot S, Liu Y, Lefevre C, Greneche J-M, Toumi M, Mhiri T, Begin-Colin S. Magnetic iron oxide nanoparticles: reproducible tuning of the size and nanosized-dependent composition, defects, and spin canting. J Phys Chem C. 2014;118(7):3795–810. https://doi.org/10.1021/jp411481p .

Wu K, Liu J, Saha R, Peng C, Su D, Wang YA, Wang J-P. Investigation of commercial iron oxide nanoparticles: structural and magnetic property characterization. ACS Omega. 2021;6(9):6274–83. https://doi.org/10.1021/acsomega.0c05845 .

Chen L, Xie J, Wu H, Li J, Wang Z, Song L, Zang F, Ma M, Gu N, Zhang Y. Precise study on size-dependent properties of magnetic iron oxide nanoparticles for in vivo magnetic resonance imaging. J Nanomater. 2018;2018:1–9. https://doi.org/10.1155/2018/3743164 .

Bumajdad A, Ali S, Mathew A. Characterization of iron hydroxide/oxide nanoparticles prepared in microemulsions stabilized with cationic/non-ionic surfactant mixtures. J Colloid Interface Sci. 2011;355(2):282–92. https://doi.org/10.1016/j.jcis.2010.12.022 .

Campos EA, Stockler Pinto DVB, de Oliveira JIS, Mattos EDC, Dutra RDCL. Synthesis, characterization and applications of iron oxide nanoparticles - a short review. J Aerosp Technol Manag. 2015;7(3):267–76. https://doi.org/10.5028/jatm.v7i3.471 .

Li Q, Kartikowati CW, Horie S, Ogi T, Iwaki T, Okuyama K. Correlation between particle size/domain structure and magnetic properties of highly crystalline Fe 3 O 4 nanoparticles. Sci Rep. 2017. https://doi.org/10.1038/s41598-017-09897-5 .

Zeinoun M, Domingo-Diez J, Rodriguez-Garcia M, Garcia O, Vasic M, Ramos M, Olmedo JJ. Enhancing magnetic hyperthermia nanoparticle heating efficiency with non-sinusoidal alternating magnetic field waveforms. Nanomaterials. 2021;11:3240. https://doi.org/10.3390/nano11123240 .

Van Berkum S, Dee J, Philipse A, Erné B. Frequency-dependent magnetic susceptibility of magnetite and cobalt ferrite nanoparticles embedded in PAA hydrogel. Int J Mol Sci. 2013;14(5):10162–77. https://doi.org/10.3390/ijms140510162 .

Mohapatra DP, Kirpalani DM. Process effluents and mine tailings: sources, effects and management and role of nanotechnology. Nanotechnol Environ Eng. 2017;2(1):1–12. https://doi.org/10.1007/s41204-016-0011-6 .

Agudelo-Giraldo JD, Restrepo-Parra E, Restrepo J. Grain boundary anisotropy on nano-polycrystalline magnetic thin films. Sci Rep. 2020. https://doi.org/10.1038/s41598-020-61979-z .

Estelrich J, Escribano E, Queralt J, Busquets M. Iron oxide nanoparticles for magnetically-guided and magnetically-responsive drug delivery. Int J Mol Sci. 2015;16(12):8070–101. https://doi.org/10.3390/ijms16048070 .

Alekseeva S, Fanta AB, Iandolo B, Antosiewicz TJ, Nugroho FA, Wagner JB, Burrows A, Zhdanov VP, Langhammer C. Grain boundary mediated hydriding phase transformations in individual polycrystalline metal nanoparticles. Nat Commun. 2017;8(1):1084. https://doi.org/10.1038/s41467-017-00879-9 .

Yu X, Ji Z. Grain boundary in oxide scale during high-temperature metal processing. Stud Grain Bound Character. 2017. https://doi.org/10.5772/66211 .

Cret BE-B, Dodi G, Shavandi A, Gardikiotis I, Serban IL, Balan V. Imaging constructs: the rise of iron oxide nanoparticles. Molecules. 2021;26:3437. https://doi.org/10.3390/molecules26113437 .

Fatima H, Kim K-S. Iron-based magnetic nanoparticles for magnetic resonance imaging. Adv Powder Technol. 2018. https://doi.org/10.1016/j.apt.2018.07.017 .

Marashdeh MW, Ababneh B, Lemine OM, Alsadig A, Omri K, El Mir L, Mattar E. The significant effect of size and concentrations of iron oxide nanoparticles on magnetic resonance imaging contrast enhancement. Res Phys. 2019;15:102651. https://doi.org/10.1016/j.rinp.2019.102651 .

Witte K, Müller K, Grüttner C, Westphal F, Johansson C. Particle size and concentration-dependent separation of magnetic nanoparticles. J Magn Magn Mater. 2017;427:320–4. https://doi.org/10.1016/j.jmmm.2016.11.006 .

Gradinaru LM, Barbalata MM, Drobota M, Aflori M, Butnaru M, Spiridon M, Doroftei F, Aradoaei M, Ciobanu RC, Vlad S. Composite materials based on iron oxide nanoparticles and polyurethane for improving the quality of MRI. Polymers. 2021;13:436. https://doi.org/10.3390/polym13244316 .

Kovář D, Malá A, Mlčochová J, Kalina M, Fohlerová Z, Hlaváček A, Hubálek J. Preparation and characterisation of highly stable iron oxide nanoparticles for magnetic resonance imaging. J Nanomater. 2017. https://doi.org/10.1155/2017/7859289 .

Peng Y, Park C, Laughlin DE. Fe 3 O 4 thin films sputter deposited from iron oxide targets. J Appl Phys. 2003;93(10):7957–9. https://doi.org/10.1063/1.1556252 .

Roy A. Nanotechnology in industrial wastewater treatment. Water Intell Online. 2014. https://doi.org/10.2166/9781780406886 .

Chavali MS, Nikolova MP. Metal oxide nanoparticles and their applications in nanotechnology. SN Appl Sci. 2019. https://doi.org/10.1007/s42452-019-0592-3 .

Reguera J, Jiménez de Aberasturi D, Henriksen-Lacey M, Langer J, Espinosa A, Szczupak B, Wilhelm C, Liz-Marzán LM. Janus plasmonic–magnetic gold–iron oxide nanoparticles as contrast agents for multimodal imaging. Nanoscale. 2017;9(27):9467–80. https://doi.org/10.1039/c7nr01406f .

Ahmadpoor F, Masood A, Feliu N, Wolfgang JP, Shojaosadati SA. The effect of surface coating of iron oxide nanoparticles on magnetic resonance imaging relaxivity. Front Nanotech. 2021. https://doi.org/10.3389/fnano.2021.644734 .

Zhou L, Yuan J, Wei Y. Core-shell structural iron oxide hybrid nanoparticles: from controlled synthesis to biomedical applications. J Mater Chem. 2011;21(9):2823–40. https://doi.org/10.1039/c0jm02172e .

Nelson N, Port J, Pandey M. Use of superparamagnetic iron oxide nanoparticles (SPIONs) via multiple imaging modalities and modifications to reduce cytotoxicity: an educational review. J Nanotheranostics. 2020;1(1):105–35. https://doi.org/10.3390/jnt1010008 .

Liu S, Zhou J, Zhang L, Guan J, Wang J. Synthesis and alignment of iron oxide nanoparticles in a regenerated cellulose film. Macromol Rapid Commun. 2006;27(24):2084–9. https://doi.org/10.1002/marc.200600543 .

Tsuzuki T. Mechanochemical synthesis of metal oxide nanoparticles. Commun Chem. 2021;4(143):1–10. https://doi.org/10.1038/s42004-021-00582-3 .

Nadeem M, Khan R, Shah N, Bangash IR, Abbasi BH, Hano C, Liu C, Ullah S, Hashmi SS, Nadhman A. A review of microbial mediated iron nanoparticles (IONPs) and its biomedical applications. Nanomaterials. 2022;12:130. https://doi.org/10.3390/nano12010130 .

Cheng Z, Tan ALK, Tao Y, Shan D, Ting KE, Yin XJ. Synthesis and characterization of iron oxide nanoparticles and applications in the removal of heavy metals from industrial wastewater. Int J Photoenergy. 2012;2012:1–5. https://doi.org/10.1155/2012/608298 .

Calderón Bedoya PA, Botta PM, Bercoff PG, Fanovich MA. Magnetic iron oxide nanoparticles obtained by mechanochemical reactions from different solid precursors. J Alloy Compounds. 2020. https://doi.org/10.1016/j.jallcom.2020.157892 .

Abdulkadir I, Abdallah HMI, Jonnalagadda SB, Martincigh BS. The effect of synthesis method on the structure, and magnetic and photocatalytic properties of hematite ( á -Fe 2 O 3 ) nanoparticles. South Afr J Chem. 2018;71:68–78. https://doi.org/10.17159/0379-4350/2018/v71a9 .

Mishra D, Arora R, Lahiri S, Amritphale SS, Chandra N. Synthesis and characterization of iron oxide nanoparticles by solvothermal method. Prot Met Phys Chem Surf. 2014;50(5):628–31. https://doi.org/10.1134/s2070205114050128 .

Sahoo S, Agarwal K, Singh A, Polke B, Raha K. Characterization of γ- and α-Fe 2 O 3 nanopowders synthesized by emulsion precipitation-calcination route and rheological behaviour of α-Fe 2 O 3 . Int J Eng, Sci Technol. 2011. https://doi.org/10.4314/ijest.v2i8.63841 .

Soetaert F, Korangath P, Serantes D, Fiering S, Ivkov R. Cancer therapy with iron oxide nanoparticles: agents of thermal and immune therapies. Adv Drug Deliv Rev. 2020. https://doi.org/10.1016/j.addr.2020.06.025 .

Fathi-Achachelouei M, Knopf-Marques H, Ribeiro da Silva CE, Barthès J, Bat E, Tezcaner A, Vrana NE. Use of nanoparticles in tissue engineering and regenerative medicine. Front Bioeng Biotech. 2019. https://doi.org/10.3389/fbioe.2019.00113 .

Arbain R, Othman M, Palaniandy S. Preparation of iron oxide nanoparticles by mechanical milling. Miner Eng. 2011;24(1):1–9. https://doi.org/10.1016/j.mineng.2010.08.025 .

Fuentes S, Zarate RA, Chavez E, Muñoz P, Díaz-Droguett D, Leyton P. Preparation of SrTiO 3 nanomaterial by a sol–sol-gel-hydrothermal method. J Mater Sci. 2009;45(6):1448–52. https://doi.org/10.1007/s10853-009-4099-y .

Chen D, Ni S, Chen Z. Synthesis of Fe 3 O 4 nanoparticles by wet milling iron powder in a planetary ball mill. China Particuology. 2007;5(5):357–8. https://doi.org/10.1016/j.cpart.2007.05.005 .

Karami H. Synthesis and characterization of iron oxide nanoparticles by solid-state chemical reaction method. J Cluster Sci. 2009;21(1):11–20. https://doi.org/10.1007/s10876-009-0278-x .

Sebehanie KG, del Rosario AV, Ali AY, Femi OE. Production of magnetite nanoparticles from Ethiopian iron ore using solvent extraction and studying parameters that affect crystallite size. Mater Res Express, IOP Publ. 2021;105016:1–9. https://doi.org/10.1088/2053-1591/abc2df .

Monshi A, Foroughi MR, Monshi MR. Modified scherrer equation to estimate more accurately nano-crystallite size using XRD. World J Nano Sci Eng. 2012;02(03):154–60. https://doi.org/10.4236/wjnse.2012.23020 .

Alcalá MD, Criado JM, Real C, Grygar T, Nejezchleba M, Subrt J, Petrovsky E. Synthesis of nanocrystalline magnetite by mechanical alloying of iron and hematite. J Mater Sci. 2004;39(7):2365–70. https://doi.org/10.1023/b:jmsc.0000019998.78 .

Agarwal, S. and Bhushan. Synthesis of iron oxide pigment by planetary milling, unpublished thesis submitted to department of metallurgical and materials engineering, National Institute of Technology, Rourkela. 2015; 1–40.

Suryanarayana C. Mechanical alloying: a novel technique to synthesize advanced materials. J Cast. 2019;2:1. https://doi.org/10.34133/2019/4219812 .

Sun X, Liang Y, Sun K. Hydrothermal synthesis of magnetite: investigation of the influence of ageing time and mechanism. Micro Nano Lett. 2015;10(2):99–104. https://doi.org/10.1049/mnl.2014.0344 .

Shao H, Lee H, Huang Y, Ko I, Kim C. Control of iron nanoparticles size and shape by thermal decomposition method. IEEE Trans Magn. 2005;41(10):3388–90. https://doi.org/10.1109/tmag.2005.855206 .

Sharifi A, Hayati R, Setoudeh N, Rezaei G. A comparison between structural and magnetic behavior of cobalt ferrite synthesized via solid-state and chemical methods. Mater Res Express. 2021;8(106103):1–11. https://doi.org/10.1088/2053-1591/ac29f7 .

Seyedi M, Haratiana S, Khakia JV. Mechanochemical synthesis of Fe 2 O 3 nanoparticles. Proc Mater Sci. 2015;11:309–13. https://doi.org/10.1016/j.mspro.2015.11.093 .

Kayani ZN, Arshad S, Riaz S, Naseem S. Synthesis of iron oxide nanoparticles by sol–gel technique and their characterization. IEEE Trans Magn. 2014;50(8):1–4. https://doi.org/10.1109/tmag.2014.2313763 .

Petcharoen K, Sirivat A. Synthesis and characterization of magnetite nanoparticles via the chemical co-precipitation method. Mater Sci Eng, B. 2012;177(5):421–7. https://doi.org/10.1016/j.mseb.2012.01.003 .

Li MY, Sui XD. Synthesis and characterization of magnetite particles by Co-precipitation method. Key Eng Mater. 2012;512–515:82–5. https://doi.org/10.4028/www.scientific.net/kem.512-515.82 .

Rasheed R, Meera V. Synthesis of iron oxide nanoparticles coated sand by biological method and chemical method. Proc Technol. 2016;24:210–6. https://doi.org/10.1016/j.protcy.2016.05.029 .

Rane AV, Kanny K, Abitha VK, Thomas S. Methods for synthesis of nanoparticles and fabrication of nanocomposites. Synth Inorg Nanomater. 2018. https://doi.org/10.1016/b978-0-08-101975-7.00005-1 .

Liu Y, Liu P, Su Z, Li F, Wen F. Attapulgite–Fe 3 O 4 magnetic nanoparticles via co-precipitation technique. Appl Surf Sci. 2008;255(5):2020–5. https://doi.org/10.1016/j.apsusc.2008.06.193 .

Patsula V, Moskvin M, Dutz S, Horák D. Size-dependent magnetic properties of iron oxide nanoparticles. J Phys Chem Solids. 2016;88:24–30. https://doi.org/10.1016/j.jpcs.2015.09.008 .

Xing L, ten Brink GH, Chen B, Schmidt FP, Haberfehlner G, Hofer F, Kooi BJ, Palasantzas G. Synthesis and morphology of iron–iron oxide core-shell nanoparticles produced by high-pressure gas condensation. Nanotechnology. 2016;27(21):215703. https://doi.org/10.1088/0957-4484/27/21/215703 .

Vergnat V, Heinrich B, Rawiso M, Muller R, Pourroy G, Masson P. Iron oxide/polymer core-shell nanomaterials with star-like behavior. Nanomaterials. 2021;2021(11):2453. https://doi.org/10.3390/nano11092453 .

Lesiak B, Rangam N, Jiricek P, Gordeev I, Tóth J, Kövér L, Borowicz P. Surface study of Fe 3 O 4 nanoparticles functionalized with biocompatible adsorbed molecules. Front Chem. 2019. https://doi.org/10.3389/fchem.2019.00642 .

Dadfar SM, Camozzi D, Darguzyte M, Roemhild K, Varvarà P, Metselaar J, Banala S, Straub M, Güvener N, Engelmann N, Slabu I, Buhl M, Leusen J, Kögerler P, Hermanns-Sachweh B, Schulz V, Kiessling F, Lammers T. Size-isolation of superparamagnetic iron oxide nanoparticles improves MRI, MPI and hyperthermia performance. J Nanobiotech. 2020;18(1):1–3. https://doi.org/10.1186/s12951-020-0580-1 .

Singh J, Dutta T, Kim K-H, Rawat M, Samddar P, Kumar P. Green synthesis of metals and their oxide nanoparticles: applications for environmental remediation. J Nanobiotechnol. 2018. https://doi.org/10.1186/s12951-018-0408-4 .

Pislaru-Danescu L, Morega A, Telipan G, Stoica V. Nanoparticles of ferrofluid Fe 3 O 4 synthetised by coprecipitation method used in microactuation process. Optoelectron Adv Mat. 2010;1(8):1182.

Signorini L, Pasquini L, Savini L, Carboni R, Boscherini F, Bonetti E, Giglia A, Pedio M, Mahnem N, Nannarone S. Size-dependent oxidation in iron/iron oxide core-shell nanoparticles. Phys Rev B. 2003. https://doi.org/10.1103/physrevb.68.195423 .

Martin JE, Herzing AA, Yan W, Li X, Koel BE, Kiely CJ, Zhang W. Determination of the oxide layer thickness in core−shell zerovalent iron nanoparticles. Langmuir. 2008;24(8):4329–34. https://doi.org/10.1021/la703689k .

Hernández-Hernández AA, Aguirre-Álvarez G, Cariño-Cortés R, Mendoza-Huizar LH, Jiménez-Alvarado R. Iron oxide nanoparticles: synthesis, functionalization, and applications in diagnosis and treatment of cancer. Chem Pap. 2020. https://doi.org/10.1007/s11696-020-01229-8 .

Thoidingjam S, Tiku AB. New developments in breast cancer therapy: role of iron oxide nanoparticles. Adv Nat Sci Nanosci Nanotech. 2017;8(2):023002. https://doi.org/10.1088/2043-6254/aa5e33 .

Yun WS, Aryal S, Ahn YJ, Seo YJ, Key J. Engineered iron oxide nanoparticles to improve regenerative effects of mesenchymal stem cells. Biomed Eng Lett. 2020. https://doi.org/10.1007/s13534-020-00153-w .

Montiel Schneider MG, Martín MJ, Otarola J, Vakarelska E, Simeonov V, Lassalle V, Nedyalkova M. Biomedical applications of iron oxide nanoparticles: current insights progress and perspectives. Pharmaceutics. 2022;14:204. https://doi.org/10.3390/pharmaceutics14010204 .

Seifalian A, Bull E, Madani S, Green M, Seifalian A. Stem cell tracking using iron oxide nanoparticles. Int J Nanomed. 2014. https://doi.org/10.2147/ijn.s48979 .

Liang Y, Xie J, Yu J, Zheng Z, Liu F, Yang A. Recent advances of high-performance magnetic iron oxide nanoparticles: Controlled synthesis, properties tuning and cancer theranostics. Nano Select. 2020;2(2):216–50. https://doi.org/10.1002/nano.202000169 .

Wierzbinski KR, Szymanski T, Rozwadowska N, Rybka JD, Zimna A, Zalewski T, Nowicka-Bauer K, Malcher A, Nowaczyk M, Krupinski M, Fiedorowicz M, Bogorodzki P, Grieb P, Kurpisz MK. Potential use of superparamagnetic iron oxide nanoparticles for in vitro and in vivo bioimaging of human myoblasts. Sci Rep. 2018. https://doi.org/10.1038/s41598-018-22018-0 .

Arias L, Pessan J, Vieira A, Lima T, Delbem A, Monteiro D. Iron oxide nanoparticles for biomedical applications: a perspective on synthesis, drugs, antimicrobial activity, and toxicity. Antibiotics. 2018;7(2):46. https://doi.org/10.3390/antibiotics7020046 .

Dadfar SM, Roemhild K, Drude NI, von Stillfried S, Knüchel R, Kiessling F, Lammers T. Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications. Adv Drug Deliv Rev. 2019. https://doi.org/10.1016/j.addr.2019.01.005 .

Zhao S, Yu X, Qian Y, Chen W, Shen J. Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics. Theranostics. 2020;10(14):6278–309. https://doi.org/10.7150/thno.42564 .

Siddiqi KS, Rahman A, Tajuddin R, Husen A. Biogenic fabrication of iron/iron oxide nanoparticles and their application. Nanoscale Res Lett. 2016. https://doi.org/10.1186/s11671-016-1714-0 .

Marcu A, Pop S, Dumitrache F, Mocanu M, Niculite CM, Gherghiceanu M, Lungua CP, Fleacaa C, Ianchis R, Barbut A, Morjan I. Magnetic iron oxide nanoparticles as drug delivery system in breast cancer. Appl Surf Sci. 2013;281:60–5. https://doi.org/10.1016/j.apsusc.2013.02.072 .

Vakili-Ghartavol R, Momtazi-Borojeni AA, Vakili-Ghartavol Z, Aiyelabegan HT, Jaafari MR, Rezayat SM, Arbabi Bidgoli S. Toxicity assessment of superparamagnetic iron oxide nanoparticles in different tissues. Artif Cells, Nanomed Biotech. 2020;48(1):443–51. https://doi.org/10.1080/21691401.2019.1709855 .

Poller J, Zaloga J, Schreiber E, Unterweger H, Janko C, Radon P, Friedrich R. Selection of potential iron oxide nanoparticles for breast cancer treatment based on in vitro cytotoxicity and cellular uptake. Int J Nanomed. 2017;12:3207–20. https://doi.org/10.2147/ijn.s132369 .

Sun S, Zeng H. Size-controlled synthesis of magnetite nanoparticles. J Am Chem Soc. 2002;124(28):8204–5. https://doi.org/10.1021/ja026501x .

Ganachari SV, Hublikar L, Yaradoddi JS, Math SS. Metal oxide nanomaterials for environmental applications. In: Martínez L, Kharissova O, Kharisov B, editors. Handbook of ecomaterials. Cham: Springer; 2019.

Dave PN, Chopda LV. Application of iron oxide nanomaterials for the removal of heavy metals. J Nanotech. 2014;2014:1–14. https://doi.org/10.1155/2014/398569 .

Xu P, Zeng GM, Huang DL, Feng CL, Hu S, Zhao MH, Lai C, Zhen Wei Z, Huang G, Xie GX, Liu ZF. Use of iron oxide nanomaterials in wastewater treatment: a review. Sci Total Environ. 2012;424:1–10. https://doi.org/10.1016/j.scitotenv.2012.02.0 .

Hasany SF, Ahmed I, Rajan J, Rehman A. Systematic review of the preparation techniques of iron oxide magnetic nanoparticles. Nanosci Nanotechnol. 2012;2(6):148–58. https://doi.org/10.5923/j.nn.20120206.01 .

Anjum M, Miandad R, Waqas M, Gehany F, Barakat MA. Remediation of wastewater using various nanomaterials. Arab J Chem. 2016. https://doi.org/10.1016/j.arabjc.2016.10.004 .

Ahmad IZ, Ahmad A, Tabassum H, Kuddus M. Applications of nanoparticles in the treatment of wastewater. Handb Ecomater. 2017. https://doi.org/10.1007/978-3-319-48281-1_37-1 .

Rahdar A, Taboada P, Aliahmad M, Hajinezhad MR, Sadeghfar F. Iron oxide nanoparticles: synthesis, physical characterization, and intraperitoneal biochemical studies in Rattus norvegicus . J Mol Struct. 2018;1173:240–5. https://doi.org/10.1016/j.molstruc.2018.06.098 .

Pourmadadi M, Rahmani E, Shamsabadipour A, Mahtabian S, Ahmadi M, Rahdar A, Díez-Pascual AM. Role of iron oxide (Fe 2 O 3 ) nanocomposites in advanced biomedical applications: a state-of-the-art review. Nanomaterials. 2022;12(3873):1–29. https://doi.org/10.3390/nano12213873 .

Taimoory SM, Rahdar A, Aliahmad M, Sadeghfar F, Hajinezhad MR, Jahantigh M, Shahbazi P, Trant JF. The synthesis and characterization of a magnetite nanoparticle with potent antibacterial activity and low mammalian toxicity. J Mol Liq. 2018;265:96–104. https://doi.org/10.1016/j.molliq.2018.05.105 .

Ezealigo US, Ezealigo BN, Aisida SO, Ezema FI. Iron oxide nanoparticles in biological systems: antibacterial and toxicology perspective. JCIS Open. 2021. https://doi.org/10.1016/j.jciso.2021.100027 .

De Carvalho JF, de Medeiros SN, Morales MA, Dantas AL, Carriço AS. Synthesis of magnetite nanoparticles by high-energy ball milling. Appl Surf Sci. 2013;275:84–7. https://doi.org/10.1016/j.apsusc.2013.01.118 .

Modan EM, Cursaru LM, Piticescu RM, Negrea DA, Moga SG, Ducu CM. Synthesis and characterization of magnetite nanoparticles. Smart Energy Sustain Environ. 2023;26(1):5–12. https://doi.org/10.46390/j.smensuen.26123.452 .

Ansari K, Ahmad R, Tanweer MS, Azam I. Magnetic iron oxide nanoparticles as a tool for the advancement of biomedical and environmental application: a review. Biomed Mater Devices. 2023. https://doi.org/10.1007/s44174-023-00091-y .

Jiang M, Althomali RH, Ansari SA, Musad EA, Saleh JG, Kambarov KD, Alsaab HO, Alwaily ER, Hussien BM, Mustafa YF, Bagher Farhood AN. Advances in preparation, biomedical, and pharmaceutical applications of chitosan-based gold, silver, and magnetic nanoparticles: a review. Int J Biol Macromol. 2023. https://doi.org/10.1016/j.ijbiomac.2023.126390 .

Barabadi H , and Kamyar J, Pishgahzadeh E, Morad H and Vahidi H Penicillium species as an innovative microbial platform for bioengineering of biologically active nanomaterials. 2023; https://doi.org/10.1201/9781003327387-4.

Baabu PRS, Kumar HK, Gumpu MB, Babu KJ, Kulandaisamy AJ, Rayappan JBB. Iron oxide nanoparticles: a review on the province of its compounds. Proper Biol Appl Mater. 2023;16(1):59. https://doi.org/10.3390/ma16010059 .

Vernet-Crua A, Cruz D M, Mostafavi E, Truong L B, Barabadi H, Cholula-Díaz J L, Guisbiers G and Webster T J. Green-synthesized metallic nanoparticles for antimicrobial applications, In: Nanomedicine: technology and application, biomaterials (2nd Edition), 2023; 297–338, https://doi.org/10.1016/B978-0-12-818627-5.00014-2

Saravanan M, Barabadi H, Vahidi H. Green Nanotechnology: Isolation of bioactive molecules and modified approach of biosynthesis. Micro Nano Technol, Biogenic Nanopart Cancer Theranostic. 2021. https://doi.org/10.1016/B978-0-12-821467-1.00005-7 .

Morad H, Jounaki K, Ansari M, Sadeghian-Abadi S, Vahidi H, Barabadi H. Bioengineered metallic nanomaterials for nanoscale drug delivery systems. In: Barabadi H, Mostafavi E, Saravanan M, editors. Pharmaceutical nanobiotechnology for targeted therapy. Springer, Cham: Nanotechnology in the Life Sciences; 2022.

Barabadi H, Jounaki K, Pishgahzadeh E, Morad H, Bozorgchami N, Vahidi H. Bioengineered metal-based antimicrobial nanomaterials for surface coatings. In Antiviral and Antimicrobial Smart Coatings: Fundamentals and Applications; 2023. https://doi.org/10.1016/B978-0-323-99291-6.00012-8 .

Book   Google Scholar  

Agrawal NK, Gangal D, Agarwal R, Jhakar N, Palsania HS. Preparation of magnetic iron oxide nanoparticles by the modified wet chemical method. Res Rev: J Phys https://doi.org/10.37591/RRJoPHY

Hernández-Hernández AA, Aguirre-Álvarez G, Cariño-Cortés R, Mendoza-Huizar LH, Rubén Jiménez-Alvarado R. Iron oxide nanoparticles: synthesis, functionalization, and applications in diagnosis and treatment of cancer. Chem Pap. 2020;74:3809–24. https://doi.org/10.1007/s11696-020-01229-8 .

Fathi-Achachelouei M, Knopf-Marques H, Ribeiro DCE, Barthès J, Bat E, Tezcaner A, Vrana NE. Use of nanoparticles in tissue engineering and regenerative medicine. Front Bioeng Biotech. 2019;24(7):113. https://doi.org/10.3389/fbioe.2019.00113 .

Vélez E, Campillo GE, Morales G, Hincapié C, Osorio J, Arnache O, Uribe JI, Jaramillo F. Mercury removal in wastewater by iron oxide nanoparticles. J Phys: Conf Ser. 2016;687:012050. https://doi.org/10.1088/1742-6596/687/1/012050 .

Garcés V, Rodríguez-Nogales A, González A, Gálvez N, Rodríguez-Cabezas ME, García-Martin ML, Gutiérrez L, Rondon D, Olivares M, Galvez J, Dominguez-Vera JM. Bacteria-carried iron oxide nanoparticles for treatment of anemia. Bioconjug Chem. 2018;29(5):1785–91. https://doi.org/10.1021/acs.bioconjchem.8b002 .

Wang H, Zhao X, Han X, Tang Z, Liu S, Guo W, Wang H, Wu F, Meng X, Giesy JP. Effects of monovalent and divalent metal cations on the aggregation and suspension of Fe 3 O 4 magnetic nanoparticles in aqueous solution. Sci Total Environ. 2017;586:817–26. https://doi.org/10.1016/j.scitotenv.2017.02.0 .

Askari HM, Hedayati SA, Qadermarzi A, Pouladi M, ZangiAbadi S, Naghshbandi N. Application of iron oxide nanoparticles in the reactor for treatment of effluent from fish farms. Iran J Fish Sci. 2020;19(3):1319–28. https://doi.org/10.22092/ijfs.2019.120641 .

Lunge S, Singh S, Sinha A. Magnetic iron oxide (Fe 3 O 4 ) nanoparticles from tea waste for arsenic removal. J Magn Magn Mater. 2014;356:21–31. https://doi.org/10.1016/j.jmmm.2013.12.008 .

Araújo R, Castro ACM, Fiúza A. The use of nanoparticles in soil and water remediation processes. Mater Today: Proc. 2015;2(1):315–20. https://doi.org/10.1016/j.matpr.2015.04.055 .

Demangeat E, Pédrot M, Dia A, Bouhnik-Le-Coz M, Roperch P, Compaoré G, Cabello-Hurtado F. Investigating the remediation potential of iron oxide nanoparticles in Cu-polluted soil-plant systems: coupled geochemical, geophysical and biological approaches. Nanoscale Adv. 2021;3(7):2017–29. https://doi.org/10.1039/d0na00825g .

Karthick A, Roy B, Chattopadhyay P. Comparison of zero-valent iron and iron oxide nanoparticle stabilized alkyl polyglucoside phosphate foams for remediation of diesel-contaminated soils. J Environ Manag. 2019;240:93–107. https://doi.org/10.1016/j.jenvman.2019.03.088 .

Saharan P, Chaudhary GR, Mehta SK, Umar A. Removal of water contaminants by iron oxide nanomaterials. J Nanosci Nanotechnol. 2014;14(1):627–43. https://doi.org/10.1166/jnn.2014.9053 .

Gutierrez AM, Dziubla TD, Hilt JZ. Recent advances on iron oxide magnetic nanoparticles as sorbents of organic pollutants in water and wastewater treatment. Rev Environ Health. 2017. https://doi.org/10.1515/reveh-2016-0063 .

Matei E, Predescu A, Vasile E, Predescu A. Properties of magnetic iron oxides used as materials for wastewater treatment. J Phys Conf Ser. 2011;304:012022. https://doi.org/10.1088/1742-6596/304/1/012022 .

Qasem NAA, Mohammed RH, Lawal DU. Removal of heavy metal ions from wastewater: a comprehensive and critical review. npj Clean Water. 2021. https://doi.org/10.1038/s41545-021-00127-0 .

Suman SV, Devi S, Chahal S, Singh JP, Chae KH, Kumar A, Asokan., K. and Kumar, P. Phase transformation in Fe 2 O 3 nanoparticles: electrical properties with local electronic structure. Phys B: Condensed Matter. 2021;620:413275. https://doi.org/10.1016/j.physb.2021.413275 .

Iwasaki T, Sato N, Kosaka K, Watano S, Yanagida T, Kawai T. Direct transformation from goethite to magnetite nanoparticles by mechanochemical reduction. J Alloy Compd. 2011;509(4):L34–7. https://doi.org/10.1016/j.jallcom.2010.10.029 .

Woo K, Hong J, Choi S, Lee H-W, Ahn J-P, Kim CS, Lee SW. Easy synthesis and magnetic properties of iron oxide nanoparticles. Chem Mater. 2004;16(14):2814–8. https://doi.org/10.1021/cm049552x .

Kheshtzar R, Berenjian A, Ganji N, Taghizadeh S-M, Maleki M, Taghizadeh S, Taghizadeh S, Ghasemi Y, Ebrahiminezhad A. Response surface methodology and reaction optimization to product zero-valent iron nanoparticles for organic pollutant remediation. Biocatal Agric Biotech. 2019. https://doi.org/10.1016/j.bcab.2019.101329 .

Tao H, Wu T, Aldeghi M, Wu TC, Aspuru-Guzik A, Kumacheva E. Nanoparticle synthesis assisted by machine learning. Nat Rev Mater. 2021;6(8):701–16. https://doi.org/10.1038/s41578-021-00337-5 .

Can MM, Ozcan S, Ceylan A, Firat T. Effect of milling time on the synthesis of magnetite nanoparticles by wet milling. Mater Sci Eng, B. 2010;172(1):72–5. https://doi.org/10.1016/j.mseb.2010.04.019 .

Darvina Y, Yulfriska N, Rifai H, Dwiridal L, Ramli R. Synthesis of magnetite nanoparticles from iron sand by ball-milling. J Phys: Conf Ser. 2019;1185:012017. https://doi.org/10.1088/1742-6596/1185/1/012017 .

Yadav TP, Yadav RM, Singh PD. Mechanical milling: a top down approach for the synthesis of nanomaterials and nanocomposites. Nanosci Nanotechnol. 2012;2(3):22–48. https://doi.org/10.5923/j.nn.20120203.01 .

Yang H, Zhang X, Ao W, Qiu G. Formation of NiFe 2 O 4 nanoparticles by mechanochemical reaction. Mater Res Bull. 2004;39(6):833–7. https://doi.org/10.1016/j.materresbull.2004.02.001 .

Tanaka S, Kaneti YV, Septiani NLW, Dou SX, Bando Y, Hossain MSA, Kim J, Yamauchi Y. A review on iron oxide-based nanoarchitectures for biomedical, energy storage, and environmental applications. Small Methods. 2019;3(5):1800512. https://doi.org/10.1002/smtd.201800512 .

Knauss M, Tolea F, Valeanu M, Diamandescu L, Trotta R, Wood K, Grabias A, Sorescu M. Mechanochemical synthesis and characterization of molybdenum dioxide-hematite nanostructures with different molarities. J Min Mater Charact Eng. 2018;6:587–600. https://doi.org/10.4236/jmmce.2018.66042 .

Shipley HJ, Engates KE, Guettner AM. Study of iron oxide nanoparticles in soil for remediation of arsenic. J Nanopart Res. 2010;13(6):2387–97. https://doi.org/10.1007/s11051-010-9999-x .

Calderón PA, Bedoya PAC, Botta PM, Bercoff PG, Fanovich MA. Influence of the milling materials on the mechanochemical synthesis of magnetic iron oxide nanoparticles. J Alloy Compd. 2023;939(168720):1–7. https://doi.org/10.1016/j.jallcom.2023.168720 .

Iwasaki T, Kosaka K, Yabuuchi T, Watano S, Yanagida T, Kawai T. Novel mechanochemical process for synthesis of magnetite nanoparticles using coprecipitation method. Adv Powder Technol. 2009;20(6):521–8. https://doi.org/10.1016/j.apt.2009.06.002 .

Shokrollahi H. A review of the magnetic properties, synthesis methods and applications of maghemite. J Magn Magn Mater. 2017;426:74–81. https://doi.org/10.1016/j.jmmm.2016.11.033 .

Iwasaki T, Sato N, Nakamura H, Watano S. An experimental investigation of aqueous-phase synthesis of magnetite nanoparticles via mechanochemical reduction of goethite. Adv Powder Technol. 2013;24(2):482–6. https://doi.org/10.1016/j.apt.2012.11.014 .

Calderón Bedoya PA, Botta PM, Bercoff PG, Fanovich MA. Magnetic iron oxides nanoparticles obtained by mechanochemical reactions from different solid precursors. J Alloy Compounds. 2020. https://doi.org/10.1016/j.jallcom.2S020.157892 .

Ogbezode JE, Ajide OO, Ofi O, Oluwole OO. Recent trends in the technologies of the direct reduction and smelting process of iron ore/iron oxide in the extraction of iron and steelmaking. Iron Ore Iron Oxides, IntechOpen,. 2023. https://doi.org/10.5772/intechopen.1001158 .

Lin CR, Chu YM, Wang S-C. Magnetic properties of magnetite nanoparticles prepared by mechanochemical reaction. Mater Lett. 2006;60(4):447–50. https://doi.org/10.1016/j.matlet.2005.09.009 .

Ogbezode J, Ajide O, Ofi O, Oluwole O. An overview of the reduction-smelting process of iron oxides in modern-day ironmaking technology. Res Develop Mater Sci. 2022;17(4):1992–4. https://doi.org/10.31031/RDMS.2022.17.000918 .

Honary S, Barabadi H, Ebrahimi P, Naghibi F, Alizadeh A. Development and optimization of biometal nanoparticles by using mathematical methodology: a microbial approach. J Nano Res. 2015;30:106–15. https://doi.org/10.4028/www.scientific.net/jnanor.30.106 .

Khan S, Bibi G, Dilbar S, Iqbal A, Ahmad M, Ali A, Ullah Z, Jaremko M, Iqbal J, Ali M, Haq I, Ali I. Biosynthesis and characterization of iron oxide nanoparticles from Mentha spicata and screening its combating potential against Phytophthora infestans . Front Plant Sci. 2022;13:1001499. https://doi.org/10.3389/fpls.2022.1001499 .

Jung J, Cho M, Seo TS, Lee SY. Biosynthesis and applications of iron oxide nanocomposites synthesized by recombinant Escherichia coli . Appl Microbiol Biotech. 2022;106(3):1127–37. https://doi.org/10.1007/s00253-022-11779-4 .

Mahlaule-Glory LM, Mapetla S, Makofane A, Mathipa MM, Hintsho-Mbita NC. Biosynthesis of iron oxide nanoparticles for the degradation of methylene blue dye, sulfisoxazole antibiotic and removal of bacteria from real water. Heliyon. 2022. https://doi.org/10.1016/j.heliyon.2022.e10536 .

Download references

This work was supported by the Partnership for Applied Science and Engineering Technology (PASET) and Research Innovation Fund (RSIF) with Grant number: B8501E21184.

Author information

Authors and affiliations.

Department of Materials Science and Engineering, African University of Science and Technology, Abuja, Nigeria

Joseph Ekhebume Ogbezode, Ucheckukwu Stella Ezealigo, Abdulhakeem Bello, Vitalis Chioh Anye & Azikiwe Peter Onwualu

Department of Mechanical Engineering, Edo State University Uzairue, Uzairue, Edo State, Nigeria

Joseph Ekhebume Ogbezode

Centre for Cyber-Physical Food, Energy and Water System (CCP-FEWS), Electrical and Electronic Engineering Science, University of Johannesburg, Johannesburg, South Africa

Abdulhakeem Bello

Department of Theoretical and Applied Physics, African University of Science and Technology, Abuja, Nigeria

You can also search for this author in PubMed   Google Scholar

Contributions

J.E.O wrote the main manuscript text. J.E.O. prepared figures 1–7. J.E.O., U.S.E. and A.B. edited the manuscript. V.C.A. and A.B. supervised the study. A.P.O. performed the visual inspection. All authors reviewed the manuscript.

Corresponding authors

Correspondence to Joseph Ekhebume Ogbezode or Abdulhakeem Bello .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Ogbezode, J.E., Ezealigo, U.S., Bello, A. et al. A narrative review of the synthesis, characterization, and applications of iron oxide nanoparticles. Discover Nano 18 , 125 (2023). https://doi.org/10.1186/s11671-023-03898-2

Download citation

Received : 08 July 2023

Accepted : 11 September 2023

Published : 10 October 2023

DOI : https://doi.org/10.1186/s11671-023-03898-2

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Green synthesis
• Characterization
• Applications
• Find a journal
• Publish with us
• Track your research

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• Nanomaterials (Basel)

Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications

1 Department of Environmental Science, Lahore College for Women University, Lahore 54000, Pakistan; [email protected]

2 School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

Arifa Tahir

Yongsheng chen.

Recent advances in nanoscience and nanotechnology have also led to the development of novel nanomaterials, which ultimately increase potential health and environmental hazards. Interest in developing environmentally benign procedures for the synthesis of metallic nanoparticles has been increased. The purpose is to minimize the negative impacts of synthetic procedures, their accompanying chemicals and derivative compounds. The exploitation of different biomaterials for the synthesis of nanoparticles is considered a valuable approach in green nanotechnology. Biological resources such as bacteria, algae fungi and plants have been used for the production of low-cost, energy-efficient, and nontoxic environmental friendly metallic nanoparticles. This review provides an overview of various reports of green synthesised zero valent metallic iron (ZVMI) and iron oxide (Fe 2 O 3 /Fe 3 O 4 ) nanoparticles (NPs) and highlights their substantial applications in environmental pollution control. This review also summarizes the ecotoxicological impacts of green synthesised iron nanoparticles opposed to non-green synthesised iron nanoparticles.

1. Introduction

Nanotechnology is the ability to measure, see, manipulate and manufacture things on an atomic or molecular scale, usually between one and 100 nanometres. These tiny products also have a large surface area to volume ratio, which is their most important feature responsible for the widespread use of nanomaterials in mechanics, optics, electronics, biotechnology, microbiology, environmental remediation, medicine, numerous engineering fields and material science [ 1 ]. Different protocols have been designed for the production of metallic nanoparticles. Currently, two main approaches are used to synthesize nanoparticles, referred to as the top-down and bottom-up approaches. Briefly, in the top-down approach, nanoparticles are produced by size reduction of bulk material by lithographic techniques and by mechanical techniques such as machining and grinding, etc., while, in bottom-up approach, small building blocks are assembled into a larger structure, e.g., chemical synthesis [ 2 ]. However, the most acceptable and effective approach for nanoparticle preparation is the bottom-up approach, where a nanoparticle is “grown” from simpler molecules known as reaction precursors. In this way, it is likely possible to control the size and shape of the nanoparticle depending on the subsequent application through variation in precursor concentrations and reaction conditions (temperature, pH, etc.) [ 3 ].

Physical and chemical methods are being used extensively for production of metal and metal oxide nanoparticles. However, this production requires the use of very reactive and toxic reducing agents such as sodium borohydride and hydrazine hydrate, which cause undesired detrimental impacts on the environment, plant and animal life it supports. Researchers continue efforts to develop facile, effective and reliable green chemistry processes for the production of nanomaterials. Various organisms act as clean, eco-friendly and sustainable precursors to produce the stable and well functionalised nanoparticles. These may include bacteria, actinomycetes, fungi, yeast, viruses, etc. [ 4 , 5 ]. Thus, it is vitally important to explore a more reliable and sustainable process for the synthesis of nanomaterials. Economic viability, environmental sustainability, and social adaptability as well as the availability of local resources are a matter of concern in the production of nanomaterials ( Figure 1 ). In order to keep the prices of the final finished nanotechnology-based products affordable to consumers, industries must maintain a delicate balance between environmentally sound green processes and their sustainability. The green nanotechnology-based production processes operate under green conditions without the intervention of toxic chemicals.

Sustainable green nanotechnology.

Many recent studies have indicated the potential of iron nanoparticles (NPs) for environmental remediation. Nanoscale materials such as nanoadsorbents, nanocatalysts, nanofiltration, and nanobiocides such as metal and metal oxide nanoparticles are currently being employed for remediation of water and wastewater pollutants. Among these metallic nanoparticles, iron nanoparticles (FeNPs) have promising advantages that can combat environmental pollution. The interest in nanoscale zero-valent iron (nZVI) in environmental remediation is increasing due to the reactivity of nanoscale iron having a large surface area to volume ratio [ 6 , 7 ]. The production of iron nanomaterials, such as metallic iron and oxide of iron via a more convenient greener route, is a great step forward in the development of nanomaterials. This review highlights the significance of biogenic approaches and the role of biocompatible green materials in technological and economically feasible process and practices. It also summarizes the quest for an environmentally sustainable synthesis process of iron nanomaterials for their application to the field of environmental sustainability.

2. Green Routes for the Synthesis of Metallic Iron Nanoparticles

2.1. synthesis by biocompatible green reagents.

Biopolymers : Research has been performed to utilize non-toxic synthetic biocompatible materials for the synthesis, as well as for stabilisation of magnetic nanoparticles polymer composites ( Table 1 ). In this scenario, He et al. [ 8 ] used water soluble starch for stabilisation of bimetallic Fe/Pd nanoparticles. Starch is a hydrophilic polymer, which consists of ~20% amylose; in this study, it was found that starch plays a significant role in dispersion and stabilisation of iron nanoparticles. In another study, synthesis of magnetite (Fe 3 O 4 ) nanoparticles was achieved by a biopolymer sodium alginate by redox-based hydrothermal method using FeCl 3 ·6H 2 O and urea as the starting materials. Sodium alginate fabricated nanoparticles showed uniform and spherical morphology with mean diameter of 27.2 nm [ 9 ]. Well dispersed magnetite (Fe 3 O 4 ) agar nanocomposite was prepared by co-precipitation of Fe(III) and Fe(II) ions for the first time by Jegan et al. [ 10 ].

Size, morphology and environmental application of Fe 0 /Fe 2 O 3 /Fe 3 O 4 nanoparticles synthesised by biocompatible green reagents.

Ascorbic acid : Synthesis of iron nanoparticles using ascorbic acid (Vitamin C) have been studied by Nadagouda et al. [ 11 ]. Core-shell Fe and Cu nanoparticles have been produced by using aqueous ascorbic acid (Vitamin C) which reduced the transition metal salts into their respective nanostructures. Likewise Savasari et al. [ 12 ] used ascorbic acid to produce stabilised zero valent iron nanoparticles assembled in a chain in which individual particles were round in shape with a diameter of 20 to 75 nm. Moreover, ascorbic acid has been used as functionalizing and stabilizing agent for nanoparticles. In one study, superparamagnetic iron oxide nanoparticles were coated and further functionalised by using ascorbic acid (Vitamin C) to form a stable dispersion for medical application. The transmission electron microscope (TEM) image of the coated nanoparticles revealed that particles were spherical in shape with an average particle size of 5 nm [ 13 ].

Amino acids : Krishna et al. [ 14 ] carried out research to produce amine functionalised magnetite nanoparticles by the wet chemical co-precipitation method. A highly crystalline magnetite phase was obtained by (in-situ) functionalisation with l -lysine amino acid. Similarly, Siskova et al. [ 15 ] used different amino acids such as l -glutamic acid, l -glutamine, l -arginine and l -cysteine to synthesize zero valent iron and studied the effect of pH on zero valet iron generation.

Haemoglobin and myoglobin : In one study, Sayyad et al. [ 16 ] reported the one-pot synthesis of iron nanoparticles (Fe NPs) from naturally available Fe-containing bio-precursors, i.e., haemoglobin and myoglobin. A single-phase chemical reduction reaction produced the stable iron nanoparticles at room temperature. The size distribution of the synthesised particles fall into the narrow 2–5 nm range and the particles were observed to be crystalline. This strategy can be an important valuable engineering approach for fabrication of bio-conjugated nanoparticle for biological applications.

Sugar and Glucose: Lu et al. [ 17 ] prepared polycrystalline Fe 3 O 4 nanoparticles using d -glucose as the reducing agent and gluconic acid (the oxidative product of glucose) as a stabilizer and dispersant. A detailed characterisation was performed to reveal the Fe 3 O 4 nanoparticle structures. Transmission electron microscopy (TEM) results exhibited that Fe 3 O 4 nanoparticles have a roughly spherical shape and their average size is about 12.5 nm. Sun et al. [ 18 ] synthesised magnetite (Fe 3 O 4 ) nanoparticles coated with glucose and gluconic acid via a facile hydrothermal reduction approach utilizing a single iron source i.e., FeCl 3 . In hydrothermal reduction process sucrose decomposed into reducing species, causing partial reduction of the Fe 3+ ions to Fe 2+ ions for the formation of Fe 3 O 4 , furthermore, capped the nanoparticles to change the surface properties and enable the formation of nanoparticles.

In a recent study, Yan et al. [ 19 ] utilised wood-derived sugar to synthesize carbon encapsulated iron nanoparticles under hydrothermal carbonisation conditions. Detailed characterisation was done on nanospheres, which were around 100–150 nm in diameter with an iron core diameter of 10–25 nm. The catalytic effect of carbon-encapsulated iron nanoparticles to convert the syngas into liquid hydrocarbons was evaluated by Yan et al. [ 19 ].

Synthetic tannic and Gallic acid : Herrera-Becerra et al. [ 20 ] reported the synthesis of iron oxide nanoparticles by powder tannic acid. Highly crystalline and monodisperse iron oxide (Fe 2 O 3 ) nanoparticles were prepared by aqueous suspension of tannic acid under ultrasonic treatment at a controlled pH of 10. The high resolution transmission electron microscopy (HR-TEM) results showed that the biosynthesised NPs were spherical in shape with sizes smaller than 10 nm [ 20 ]. Dorniani et al. [ 21 ] produced magnetic iron oxide nanoparticles by the sonochemical method and consequently coated the NPs with chitosan and Gallic acid to create a core-shell structure. X-ray diffraction (XRD) demonstrated that the magnetic nanoparticles were pure Fe 3 O 4 with a cubic inverse spinel morphology with an average diameter of 13 nm.

2.2. Synthesis by Microorganisms

Bacteria: Iron reducing bacteria are commonly used in synthesis of iron nanomaterials. Bharde et al. [ 22 ] synthesised spherical iron oxide nanoparticles using Actinobacter sp. under aerobic conditions. In another study, maghemite (γ-Fe 2 O 3 ) and greigite (Fe 3 S 4 ) were synthesised using the same species of bacterium by altering the iron precursor. Here, Actinobacter sp. was found to be capable of extracellular synthesis of magnetic nanoparticles when exposed to the aqueous solution of ferric salts under aerobic conditions for 48–72 h. The formation of iron oxide nanoparticles was indicated by changed in colour of reaction, medium to dark brown and further characterised by TEM, XRD, FTIR, magnetic measurements, etc. Bacterial synthesis of magnetic particles is a complex phenomenon, and synthesis involves the enzyme iron reductase produced by Actinobacer sp. in presence of iron salt. Iron reductase, reduce the Fe 3+ into Fe 2+ , extracellularly for formation magnetic particles. In this study, Fe 3+ reductase activity was confirmed by Ferrisiderophore reductase assay which indicated that extracellular iron reductase was synthesised in the presence of excess iron salt [ 23 ]. Moon et al. [ 24 ] prepared magnetite nanoparticles under anaerobic conditions using a thermophilic strain, Thermoanaerobacter sp. and FeOOH as the precursor. Extracellular magnetites exhibited good mono-dispersity with a mean diameter of 13.1 nm when analysed under transmission electron microscopy (TEM). Extracellular biosynthesis of Fe 3 O 4 nanoparticles was performed using Bacillus subtilis strains isolated from rhizosphere soil. The synthesised nanoparticles were spherical in shape and diameter in the range of 60–80 nm [ 25 ]. Elcey et al. [ 26 ] used the Thiobacillus thioparus bacterial strain isolated from iron ore mining sites. The magnetosomes had magnetic characteristics as purified particles synthesised by isolated bacterial strains with a protein coating as evidenced by the stained polyacrylamide gel.

Fungi : Different sizes of magnetic particles may be produced extracellularly by exploiting the fungi, such as Fusarium oxysporum and Verticillium sp., with mixtures of ferric and ferrous salts at room temperature. Cationic proteins secreted by the fungi cause an extracellular hydrolysis of the anionic iron complexes. Consequently, leads to formation of crystalline magnetite particles that exhibit a ferrimagnetic transition signature with insignificant amount of spontaneous magnetisation at low temperature [ 27 ]. Kaul et al. [ 28 ] tested five different species of fungi, P. chlamydosporium , A. fumigates , A. wentii , C. lunata and C. globosum , and two bacteria, A. faecalis and B. coagulans , for the production of iron nanoparticles [ 29 ]. Another group of researchers, Mohamed et al. [ 30 ], used Alternaria alternata fungus for production of Fe NPs, which has been characterised by various spectroscopic techniques. The nanoparticles were found to be 9 ± 3 nm having cubic shape. These nanoparticles exhibited antibacterial activity against B. subtilis , E. coli , S. aureus and P. aeruginosa .

Algae : Mahdavi et al. [ 31 ] worked on biosynthesis of iron oxide nanoparticles (Fe 3 O 4 NPs) by reduction of ferric chloride solution with the macroalgae, brown seaweed ( Sargassum muticum ) extract. The water extract of brown seaweed contains sulphated polysaccharides, which Mahdavi et al. used as a main factor in the reduction of iron salt. The rapid reaction was completed in one step by changing the solution colour from yellow to dark brown. The average particle diameter was 18 ± 4 nm determined by TEM. X-ray diffraction (XRD) showed that the nanoparticles were crystalline in nature, with a cubic shape. Subramaniyam et al. [ 32 ] employed soil micro algae, Chlorococcum sp., with an iron chloride precursor to synthesize the spherical-shaped nanoiron ranging in size from 20–50 nm. The surface of microalagl cell contained nanoiron, not only localised inside as well as outside the cell as revealed by TEM. It was suggested that biomolecules such as carbonyl and amine from polysaccharides and glycoproteins present in algal cell were involved in synthesis of nanoiron and confirmed by FTIR analysis. Reports on biosynthesis of iron nanoparticles from microorganisms have been summarized in Table 2 .

Size, morphology and environmental application of Fe 0 /Fe 2 O 3 /Fe 3 O 4 nanoparticles synthesised by microorganisms.

2.3. Synthesis of Iron Nanoparticles from Plant Biomaterials

Unfortunately, the production of nanomaterial from microorganisms is less monodispersed and the rate of synthesis is slow compared to plant-based synthesis [ 33 ]. According to Kalaiarasi et al. [ 34 ], green synthesis of metallic nanoparticles by different plant parts such as the leaf, stem, seed and root is the simplest, most cost effective and reproducible approach. Plants certainly produce more stable metal nanoparticles and have proved to be the best candidates for fast and large-scale synthesis as compared to microorganisms [ 35 ]. The preference for plants and their derivatives in nanomaterial production lies in the plants’ natural composition of different organic reducing compounds, which easily adapt to the synthesis of nanoparticles [ 36 ]. Different herbs and plant sources occlude higher antioxidants that are available as phytochemical constituents in seeds, fruits, leaves and stems. Therefore, the utility of plant-based phytochemicals in the overall synthesis and architecture of nanoparticles creates an important symbiosis between natural/plant sciences and nanotechnology. This association gives a characteristically green approach to nanotechnology, referred to as green nanotechnology. These production processes can be carried out without significant environmental pollution, thereby setting new standards in highly sustainable and economically viable clean and green technologies [ 37 ].

Synthesis by leaf extract: The green synthesis of iron nanoparticles using various plant extracts has been reported by many researchers. Biosynthesis of iron nanoparticles (Fe NPs) has been mainly performed using extract of green tea which is a cheap and local resource. Hoag et al. [ 38 ] synthesised nZVI utilizing green tea ( Camellia sinensis ) extract containing a range of polyphenols. Without the addition of any surfactant or polymer, the stable nanoparticles were obtained at room temperature. Polyphenols in plant act as both a reducing agent and a capping agent, resulting in stable green nanoscale zero-valent iron particles with unique properties. Green tea (20 g/L) was used for preparation of extract. A solution of 0.1 M FeCl 3 was added to (20 g/L) green tea extract in a 2:1 volume ratio resulting in spherical nanoparticles with diameter of 5–10 nm. In another study, Shahwan et al. adopted the same procedure for synthesis of iron nanoparticles with little modification. They used the 0.10 M iron chloride solution to green tea in 2:3 volume ratios. Following this, 1.0 M NaOH solution was added until the pH was 6.0 and the formation of nanoparticles was marked by the appearance of intense black precipitate. The iron particles were harvested by evaporating water from the solution. The obtained nanoparticles (40–60 nm) were then employed as a catalyst for the degradation of methylene blue and methyl orange dyes [ 39 ]. Moreover, Markova et al. [ 40 ] prepared the iron(II, III)-polyphenol complex nanoparticles with a diameter of 70 nm-sized by adding Fe(NO 3 ) 3 ·9H 2 O to the green tea extract. Fe-based nanoparticles were prepared by introducing 0.5 M Fe(NO 3 ) 3 ·9H 2 O into green tea extract in a 1:5 volume ratio under nitrogen atmosphere. Researcher’s produced zero valent iron and iron(II, III) polyphenol complex nanoparticles by utilizing green tea extract in different studies. Hence, production of nano iron with different size and properties are due to change in synthesis procedure, and most important ratio of extract to salt. Similar findings were found in study of Nadagouda et al. [ 41 ], they evaluated the effect of extract concentration on size of iron nanoparticles. Nanoscale zero valent iron (nZVI) synthesis was done at room temperature using different volumes of tea extract and Fe(NO 3 ) 3 solution. It was found that size and morphology of particles could be change by changing the concentration of extract as well as iron salt.

Machado et al. [ 42 ] evaluated the feasibility of several tree leaves for production of nZVI. In addition, the antioxidant capacity of leaf extracts was also estimated. The results reveal that dried leaves produce extracts with higher antioxidant capacities than non-dried leaves. Leaves of oak, pomegranate and green tea produced the richest extracts, and TEM analysis confirmed that nZVIs (d = 10–20 nm) can be produced utilizing these plant resources. Use of water as the solvent for preparation of the extract is considered the cheapest and greenest method for production of nanoparticles. In another study, Pattanayak and Nayak [ 43 ] used a low-cost reductant for synthesizing nanoscale zero-valent iron (nZVI) by Azadirachta indica (neem) leaves extract under atmospheric conditions. The UV-Vis spectroscopy of synthesised iron nanoparticles were in the range of 216–265 nm. The size of spherical iron nanoparticles was predominantly found within the range of 50–100 nm.

Wang [ 44 ] synthesised stable iron-polyphenol complex nanoparticles (Fe-P NPs) using leaf extract of eucalyptus. Similarly in another study Wang et al. [ 45 ] utilised three different plants i.e., Eucalyptus tereticornis , Melaleuca nesophila and Rosemarinus officinalis to produce iron ions polyphenols complex nanoparticles (Fe-P NPs) ranging in sizes from 50 to 80 nm were. Luo et al. [ 46 ] produced Fe NP with an average size of 60 nm by utilizing methanolic grape leaf extract. Gas chromatography-mass spectrometry (GC-MS) analysis confirmed the presence of biomolecules including phytols, terpenoids, and antioxidants which involved in synthesis of nanoparticles.

Plants materials are capable of synthesize crystalline magnetite nanoparticles. Crystalline monodisperse magnetite (Fe 3 O 4 ) nanoparticles were synthesised by the carob leaf in a one-step reaction [ 47 ]. An aqueous solution of ferric chloride hexahydrate and ferrous chloride tetra hydrate (2/1 molar ratio) was mixed, and magnetite nanoparticles with an average diameter of 8 nm were obtained. The Fourier transform infrared (FTIR) spectra of carob leaf extract showed NH stretching and OH overlapping of the stretching vibration band attributed to water and carob leaf extract molecules. Pattanayak and Nayak [ 48 ] exploited the different plant resources such as mango leaves, green tea leaves, rose leaves, oregano leaves and curry leaves for production of metallic iron nanoparticles. Remarkable changes in colour and pH were observed during the reduction of iron salt by extracts. Such rapidly processed plant-mediated iron metallic nanoparticles is an alternative to chemical synthesis protocols and can serve as a low cost reductant for synthesizing iron nanoparticles. Rapid synthesis of crystalline iron oxide nanoparticles (Fe 3 O 4 ) was performed by reduction of ferric chloride (FeCl 3 ) with leaf extract of Tridax procumbens . The water extract of T. procumbens contains water soluble carbohydrate compounds. Carbohydrates containing aldehyde groups may reduce the Fe 3+ of ferric chloride to Fe 3 O 4 nanoparticles [ 49 ].

Fe 0 /Fe 3 O 4 nanoparticles were successfully synthesised using pomegranate ( Punica granatum ) leaf extract by Rao et al. [ 50 ]. Leaf extract of pomegranate was prepared in water in a 1:10 ratio w / v . Optimum synthesis was done by adding the extract (1.2 mL) to 6 mL iron salts mixtures (mixture of 0.2 M ammonium ferrous sulphate ((NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O) and 0.2 M ammonium ferric sulphate (NH 4 Fe(SO4) 2 ·12H 2 O)) in a 1:2 ratio. The reaction was maintained for 30 min at 30 °C, under stirring and for conversion of excess iron species into Fe 3 O 4 , 1 N NaOH was added. The product was separated out by centrifugation at 6000× g for 15 min. These nanoparticles were utilised for modification of two strains (NCIM 3589 and NCIM 3590) of heat-killed yeast cells Yarrowia lipolytica , which were further employed as biosorbents to remove hexavalent chromium. The biocomposites showed the presence of Fe 0 /Fe 3 O 4 when analysed by Mössbauer spectroscopy. The XRD profiles of the magnetic precipitate could be indexed to magnetite while SEM images showed the uniform distribution of iron nanoparticles on surface of yeast cells.

Makarov et al. [ 51 ] reported the synthesis of iron oxide nanoparticles using aqueous extract of Hordeum vulgare and Rumex acetosa. Hordeum vulgare produced the amorphous iron oxide (Fe 3 O 4 ) nanoparticles with a particle size up to 30 nm. The role of pH was considerable in the stability of iron nanoparticles. The authors of this paper found that the stability of H. vulgare synthesised iron nanoparticles was increased by adding 40 mM of citrate buffer with pH 3.0. Similarly, amorphous iron nanoparticles with a diameter of 10–40 nm was produced by extract of Rumex acetosa. R. acetosa extract synthesised iron nanoparticles were highly stable due to low pH (pH = 3.7) as compared to H. vulgare (pH 5.8).

In recent study, Prasad et al. [ 52 ] produced iron(III) oxide nanocrystals with leaf extract of Garlic Vine and FeSO 4 ·7H 2 O. The bio-precipitation was accelerated by adding a few drops of 1 M NaOH to obtain pH 6. The reaction resulted in formation of β-Fe 2 O 3 of nanocrystals with size of 18.22 nm. According to XRD results, iron predominantly occupying the octahedral in iron(III) oxide nanocrystals. The band gap energy 2.84 eV endorsed the semiconducting transition. Furthermore, thermogravimetric analysis (TGA) measurements showed the organic coating over the surface of nanoparticles which confirmed that biomolecules stabilised the nanoparticles. Furthermore, at above temperature 500 °C, β-Fe 2 O 3 sample undergoes to a complete phase transformation of meta-stable β-Fe 2 O 3 to stable α-Fe 2 O 3 .

Fruit extract: Some researchers use fruits for synthesis of iron nanomaterials. Mohan Kumar et al. [ 53 ] synthesised palladium and iron NPs using aqueous fruit extract of Terminalia chebula . Redox potential of polyphenolic rich T. chebula aqueous extract was 0.63 V vs. SCE (saturated calomel electrode) by cyclic voltammetry. Such a reduction helps to reduce the iron precursors to iron NPs. Remarkable stable iron nanoparticles were synthesised via simultaneous reduction of FeSO 4 ·7H 2 O solution by T. chebula extract containing complexation of polyphenols. A 5:1 ratio of extract to metal salt solution was used and solid product was separated out by centrifugation followed by ethanolic washing. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses revealed that amorphous iron NPs were within a size of less than 80 nm.

In another study Kumar et al. [ 54 ] synthesised Fe 3 O 4 nanoparticles by the fruit extract of Passiflora tripartitavar mollissima and studied their catalytic effect on the synthesis of 2-arylbenzimidazole under room temperature. Using aqueous extract of Passiflora tripartitavar , mollissima fruit spherical iron oxide nanoparticles of 22.3 ± 3 nm size were synthesised. The synthesised nanocatalyst is highly active for the synthesis of biologically significant 2-arylbenzimidazoles. Benzimidazole moiety is a structural isostere of naturally occurring nucleotides; hence, it has been useful in creating intermediates in the development of molecules for pharmaceutical and biological purposes. The one-pot synthesis of 2-arylbenzimidazole derivatives using Fe 3 O 4 nanoparticles is environmentally benign, selective, and easy to manipulate. Additionally, the Fe 3 O 4 nanoparticles as a heterogeneous catalyst could be reused five times for fresh reactions with a slight change in reactivity.

Seed extract: Seed extract of Syzygium cumini was used as a reducing agent and sodium acetate as an electrostatic stabilizing agent for the synthesis of iron oxide nanoparticles by Venkateswarlu et al. [ 55 ]. The XRD study reveals that the synthesised spherical magnetic nanoparticles (SMNPs) have inverse spinel face-centred cubic structure 9–20 nm in diameter as shown by TEM. The presence of polyphenols, flavonoids, and other biomolecules in the S. cumini seed was confirmed by Fourier transform infrared (FTIR) spectroscopy technique. The Brunauer–Emmett–Teller (BET) surface area of the Fe 3 O 4 particles was found to be 3.517 m 2 /g, and the particles were classified as mesoporous. The average pore size for the Fe 3 O 4 was determined according to the single-point adsorption total volume at a relative pressure P/P O = 0.9905 cm 3 /g. By virtue of this property, the as-synthesised nanoparticles can be used in the field of environmental remediation for the removal of toxic metals and dyes.

2.4. Other Plant Materials

Alfalfa biomass : Beccera and his collaborators used a green chemistry method to obtain biosynthesised iron oxide nanoparticles with sizes of less than 5 nm. Medicago sativa (alfalfa) biomass represented the first time iron oxide nanoparticles were produced). Milled powder of Medicago sativa was introduced to the salt solution of ferrous ammonium sulphate, and the effect of pH conditions was determined during the synthesis. The role of pH was determined as a size-limiting parameter for iron nanoparticle synthesis. Becerra et al. [ 56 ] found the optimum pH to obtain nanoparticles of size less than 10 nm (pH = 10). In the second study, more emphasis was placed on advanced characterisation techniques to electron microscopy-based characterisation of the above mentioned iron oxide nanoparticles. Under optimal conditions (pH = 10) aggregates of 1–10 nm were found. Often when nanoparticles were immersed in the alfalfa biomass that served as a base, the observation of nanoparticles became difficult, especially for those of less than 10 nm. Based on highly advanced techniques like the high angle annular dark field (HAADF), Z contrast was used to locate the nanoparticles in alfalfa biomass. Energy dispersive spectroscopy (EDS) and high resolution transmission electron microscopy (HR-TEM) were used for further characterisation of the synthesised nanoparticles [ 57 ].

Sorghums bran: Njagi et al. [ 58 ] explored the diverse phenolic compounds of sorghum bran for the synthesis of iron metallic nanoparticles. Reaction was carried out at room temperature for 1 h by adding 0.1 M FeCl 3 solution to the sorghum bran extract in a 2:1 volume ratio. The HR-TEM analysis reveals that sorghum bran mediated iron nanoparticles were amorphous in nature with a diameter of 40–50 nm. The HR-TEM result also reveals that spherical iron nanoparticles were well dispersed and capped with water soluble hetero-cyclic components present in the sorghum extracts. Further, sorghum bran mediated iron nanoparticles used as catalyst for degradation of bromothymol blue.

Plant peel extract: The facile green synthesis of magnetite nanoparticles was performed by using plantain peel extract. Venkateswarlu et al. [ 59 ] used waste plantain peel extract for reduction of iron salt to form Fe 3 O 4 nanoparticles. Biomolecules present in the plantain peel extract was characterised by FTIR. The well dispersed spherical magnetic NPs (MNPs) sized below 50 nm were seen in a transmission electron microscopic image. The Brunauer–Emmett–Teller (BET) surface area of iron MNPs was 11.31 m 2 /g while higher saturation magnetisation was 15.8 emu/g. The obtained MNPs showed excellent magnetic behaviour and on the basis of BET surface area and pore volume results, the structure of nanoparticles was assigned to be mesoporous. By virtue of this property, as-synthesised nanoparticles can be used in the field of environmental remediation for the removal of toxic metals and dyes.

Hydrothermal synthesis using plant extract: Ahmmad et al. [ 60 ] successfully synthesised highly pure hematite α-Fe 2 O 3 nanoparticles by the hydrothermal synthesis method using green tea ( Camellia sinensis ) leaf extract. TEM images of hematite α-Fe 2 O 3 showed nanoparticle spherical and highly porous particles with an average diameter of 60 nm. The surface area of the as-synthesised nanoparticles (22.5 m 2 /g) was four times higher, whereas the photocatalytic activity (capacity to generate OH radical when irradiated with visible light) was found to be about two times higher than commercially available hematite nanoparticles.

The photocatalytic activity of nanoparticle was assessed by measuring the amount of hydroxyl radical ions produced under irradiation of visible light. The as prepared α-Fe 2 O 3 exhibited two time’s higher photocatalytic activity and better performance in a photo-electrochemical cell than commercial α-Fe 2 O 3 . Phumying et al. [ 61 ] synthesised Fe 3 O 4 nanoparticles by the hydrothermal method using aloe vera plant extract and ferric acetylacetonate (Fe(C 5 H 8 O 2 ) 3 ). TEM revealed that synthesised nanoparticles were crystalline in nature having particle sizes of 6–30 nm. Morphology and chemical constituent was characterised by XRD and HR-TEM and results showed that synthesised Fe 3 O 4 nanoparticles were inverse cubic spinel in structure without any phase impurities. Based on the coercivity, it was concluded that the nanoparticles were superparamagnetic in nature. The authors observed that increasing the reaction temperature and time resulted in magnetite nanoparticles with enhanced crystallinity and saturated magnetisation.

Table 3 summarizes the recent reports on synthesis of iron nanoparticles from plants and related materials.

Size, morphology and environmental application of Fe 0 /Fe 2 O 3 /Fe 3 O 4 nanoparticles synthesised by different parts of plants and plants material.

2.5. Possible Mechanism of Nanoparticles Synthesis

Actual mechanism of nanoparticles synthesis by living organisms is not yet clear, however studies shows that enzymes produced from bacteria and fungi and biomolecules especially phenolic compounds in plant products cause the production of metallic iron nanoparticle [ 23 , 24 , 46 ]. In one study, Becerra et al. [ 20 ] utilised tannin powder a green reagent for synthesis of iron oxide NPs. Tannins consist of non-toxic polyphenolic compounds which act as reducing and stabilizing agents for the production of iron oxide NPs. According to them, most likely the presence of phenolic-OH groups and ortho-dihydroxyphenyl groups in chemical structure of tannins are involved in the formation of complexes with iron and also take part in redox reactions. In the formation of iron oxide NPs by tannins, the reactions undergo changes in electron structure. Tannins are oxidised to quinines and, by this reaction, iron salt is reduced to iron oxide nanoparticles.

Likewise, presence of biomolecules or combinations of chemically complex biomolecules, e.g., enzymes, amino acids, proteins, Vitamins, and polysaccharides, and organic acids such as citrates, may act as reducing and capping agents in nanoparticle synthesis [ 35 ]. The mechanism behind plant extract mediated metallic nanoparticle formation has not been clearly defined up until now. Not a single biomolecule of plant extract was involved in the fabrication of nanoparticles. Various plant components are rich in secondary metabolites and responsible for synthesis of metallic nanoparticles. Secondary metabolites include the polyphenols, flavonoids, tannic acid, terpenoids, ascorbic acids, carboxylic acids, aldehydes and amides. Many reducing sugars are commonly found in plants, and their presence is confirmed by the IR spectroscopic technique in different studies [ 62 ]. Phyto-chemicals in plant extracts possess ideal redox properties that allow efficient reduction of metal precursors for conversion into their corresponding metallic nanoparticles. In another study Becerra et al. [ 57 ] utilised the tannin of alfalfa. According to the assumption, tannins associated to alfalfa, derivate into radical tannins “R” causes reduction of metal under the influence of pH. The bioreduction process can be induced in the following way:

In another study, Wang [ 44 ] proposed the iron-polyphenol complex nanoparticles (Fe-P NPs) structure, synthesised by Eucalyptus leaves. Reduction potential in Eucalyptus extract is due to polyphenols which make it able to reduce Fe 3+ into Fe 2+ . However, extract does not completely reduce the Fe 2+ to zero-valent iron. Fe 2+ strongly stabilizes due to poylphenols ligands but rapidly oxidize in the presence of oxygen to give Fe 3+ -polyphenol complexes, this phenomenon commonly known as autoxidation. Thus, on reaction of iron metal solution with plants extract yields a black nano-iron colloid. A X-ray absorption (XAS) spectroscopy technique investigation suggested that plant polyphenols made chelate with ferric ion (Fe 3+ ) and found in globular position ( Figure 2 a). Similar reaction mechanism was proposed for Sage ( Salvia officinalis ) mediated iron-polyphenol complex nanoparticles by Wang et al. [ 63 ]. Plant polyphenols and can be crosslinked by condensation of polyphenol on reaction between FeCl 3 and plant polyphenol, as can be seen in Figure 2 b.

( a ) Proposed chemical structure of Fe-P NPs [ 48 ]; and ( b ) proposed condensation mechanism of Fe-polyphenol [ 63 ].

3. Environmental Applications of Green Iron Nanoparticles

There are several green approaches to synthesize iron-based nanomaterials using different bio-chemicals and bio-reducing agents. Iron nanomaterials are significantly important for abatement of environmental pollution such as degradation of organic dyes, chlorinated organic pollutants and heavy metals removal, e.g., arsenic. Details about environmental applications of greener iron nanoparticles are as follows.

3.1. Degradation of Dyes

Hoag et al. [ 38 ] employed green tea (GT) synthesised iron nanoparticles to catalyse hydrogen peroxide for the degradation of the organic contaminant (bromothymol blue). The catalytic activity of green synthesised nanoscale zero-valent iron was more than that of Fe-EDTA and Fe-EDDS. From experiments, it was observed that by increasing concentrations of GT-nZVI, more hydrogen peroxide catalysed, which ultimately increased the degradation of bromothymol blue. Similarly, the reactivity of iron nanoparticles synthesised by aqueous sorghum bran extracts was tested for degradation of dye bromothymol blue by Njagi et al. [ 56 ]. In presence of iron nanoparticles and H 2 O 2 , Bromothymol blue degrades rapidly, demonstrating that the iron nanoparticles catalyses the reaction for production of free radicals from H 2 O 2 . The catalysis of H 2 O 2 prompting the rate of reaction ultimately increases the rate of degradation of bromothymol blue [ 58 ].

In another report, green tea synthesised nZVI (Fe 0 ) nanoparticles were employed for catalytic degradation of methylene blue (MB) and methyl orange (MO) dyes. The results indicate that the complete removal of methylene blue (MB) and methyl orange (MO) dyes from water was achieved at a concentration of 10–200 mg/L. As compared to MO, MB removed instantaneously as 80% of MB removed is first 5 min of reaction while 80% of MO dye removed after 1 h of reaction. Almost complete removal of the dyes was achieved after 200 min for MB and 350 min for MO, under the studied conditions. Green tea synthesised Fe nanoparticles proved to be more effective as a Fenton-like catalyst both in terms of kinetics and percentage removal compared to iron nanoparticles produced by borohydride reduction [ 39 ].

Huang et al. [ 62 ] used oolong tea extract for synthesis of iron nanoparticles (OT-Fe NP) further employed to degrade malachite green (MG). The results also showed that: first, polyphenols/caffeine in oolong tea extract acted as both reducing and capping agents in synthesis of Fe nanoparticles, leading to reduced aggregation and to increased reactivity of OT-Fe NP. Second, OT-Fe NP proved to be efficient in the degradation of MG, resulting in 75.5% of MG (50 mg/L) being removed. Kuang et al. [ 64 ] used extracts of three different teas i.e., green tea (GT), oolong tea (OT), and black tea (BT) separately for synthesis of iron nanoparticles. Synthesised iron nanoparticles were used as a catalyst for Fenton-like oxidation of monochlorobenzene (MCB). Highest degradation rate was achieved by green tea synthesised Fe NPs and was attributed to high polyphenol present in extract. Sixty-nine per cent degradation was observed for GT-Fe NPs while 53% by OT-Fe NPs and 39% by BT-Fe NPs in 180 min. Oxidative degradation mechanism was proposed for green tea synthesised iron nanoparticles and as follows.

At first, the MCB adsorbs onto the surface of Fe NPs and iron oxide formed in the Fe corrosion, as in Equations (4) and (5).

(1) Adsorption process:

Fe 2+ and Fe 3+ leach from Fe 0 and iron oxides on the surface of Fe NPs, as shown in Equations (6) and (7), and this process accelerates the decomposition of H 2 O 2 and generates highly oxidative OH · radicals when Fe 2+ was oxidised by H 2 O 2 into Fe 3+ (8)

(2) The process of generating hydroxyl radicals’ species:

In the meantime, generated Fe 2+ and Fe 3+ in the solution will react with H 2 O and yield oxyhydroxide Equation (9), which can also adsorb MCB. Furthermore, Fe 3+ on the surface of Fe NPs was converted into Fe 2+ and HO 2 · and the generated HO 2 · possibly further react with Fe 3+ and favoured the decomposition of H 2 O 2 .

(3) Hydroxyl radicals’ species attack the MCB on the surface of Fe NPs:

Meanwhile, the generation of radical species rapidly reacts with the adsorbed MCB and also attacks MCB, resulting in mineralisation of some part of MCB on surface of Fe NPs into CO 2 and H 2 O, which also involve in removal of COD (chemical oxygen demand). In reaction time of 180 min, the rate of dye degradation (81%) was high then and removal of COD (31%). The study illustrates that the complete mineralisation during Fenton-like process is not possible when COD content is high.

Iron ions polyphenol complex nanoparticles were effectively applied for degradation of dyes. Wang [ 44 ] employed stable colloidal iron-polyphenol complex nanoparticles (Fe-P NPs) mediated by eucalyptus for adsorption-flocculation against Acid black 194 dye was tested. It was observed that Acid black 194 adsorbed at 1.6 g per gram of Fe-P NPs at temperature 25 °C. Iron polyphenol nanoparticles (Fe-P NPs) mediated by three different plants i.e., E. tereticornis , M. nesophila and R. officinalis were compared for decolourisation of dye by Wang et al. [ 45 ]. About 100% of Acid black dye was decolourised, and 87% removal of total organic carbon (TOC) was achieved by Fe-P NPs. E. tereticornis Fe-P NPs showed good activity against dye degradation as compared to other nanoparticles and attributed to small size and good dispersibility of particles when analysed under SEM.

Huang et al. [ 65 ] studied the experimental factors such as the volume ratio of Fe 2+ and tea extract, temperature, and pH to understand the influence of these factors on nanoparticles synthesis. Results show that there was a decline in the concentrations of Fe NPs with an increase in leaf extract because of decreasing Fe 2+ concentration. Huang et al. further studied the reactivity of synthesised nanoparticles for degradation of dye, malachite green (MG). Degradation of MG by Fe NPs was influenced synthesised condition, pH whereas the high temperature also influenced on reactivity. In another study Luo et al. [ 46 ] utilised grape leaf extract mediated Fe NP for degradation of dye, acid Orange II. In this study it was found that the reactivity of plant mediated Fe NP was greater than the methanolic extract of grape leaves and Fe 2+ solution both in water and methanol. Hence, the above studies show that the plant mediated iron nanoparticles were significantly effective for the degradation of various types of dyes under different experimental conditions. As compared to the conventional Fenton reaction, the Fenton-like reaction with plant mediated iron NPs takes place in a more sustainable manner. Plant mediated nanoparticles act as Fenton-catalyst with H 2 O 2 . Generally, oxidation depends on the activity of the hydroxyl radical (OH · ) which produce in aqueous solution and due to reaction of Fe 2+ and hydrogen peroxide, H 2 O 2 (Equation (13)) as described below:

However, reaction pathway may be varying for different catalysts, or may depend on chemical nature of the catalyst as well as for the dye.

3.2. Removal of Heavy Metals

Rao et al. [ 50 ] used bio nanocomposite (phyto-mediated Fe 0 /Fe 3 O 4 nanoparticles and yeast cells) to evaluate its capacity to remove hexavalent chromium which were proved to be good biosorbents. The sorption capacity of magnetically modified yeast cells was three times more than that of unmodified yeast cells. At the initial chromium concentration of 1000 mg/L and under optimum conditions, modified NCIM 3589 showed better adsorption capacity (186.32 mg/g) than modified NCIM 3590 (137.31 mg/g).

Madhavi et al. [ 66 ] reported a single-step synthesis of zero-valent iron nanoparticles (ZVNI) at room temperature using the Euclaptus globules leaf extract. The reaction for synthesis of iron nanoparticles was increased by adding more extract. FTIR spectroscopy provided the information about the vibrational state of adsorbed molecules and, hence, the nature of surface complexes. The phytogenic Fe 0 nanoparticles (ZVNI) were further used for the adsorption of Cr(VI) metal. Adsorption parameters such as dose of adsorbent (ZVNI), initial concentration of Cr(VI) and kinetics were also studied by batch experiments. The highest adsorption efficiency of ZVNI was 98.1% at reaction time of 30 min, and dosage of ZVNI was 0.8 g/L. One occurrence of particular interest was that phyto-synthesised iron nanoparticles (ZVNI) were stabilised and remained in that state for up to two months after preparation. Likewise Savasari et al. [ 12 ] synthesised green ZVIN by ascorbic acid, which was employed for reduction of Cd(II) from aqueous and ascorbic acid synthesised nanoparticles proved to be stable and efficient.

In two different studies, Mystrioti et al. produced stable colloidal suspensions of nZVI coated with polyphenol of green tea and studied their chromium removal efficiency from groundwater as well as their transport characteristics through representative porous media [ 67 , 68 ]. The effectiveness of the resulting GT-nZVI suspension with diameter of 5–10 nm was evaluated for the removal of hexavalent chromium Cr(VI) from polluted groundwater flowing through the permeable soil bed. Green tea extract is characterised as a higher antioxidant compound due to presence of polyphenols. Polyphenols enriched green tea extract plays dual role in synthesis of nZVI, since they have capability to reduce ferric cations, meanwhile shield nZVI from being oxidised and agglomerated, functioning as capping agents. Column tests were performed at different flow rates in order to analyse the effect of contact time between the nZVI attached on porous media and the flow-over solution on reduction of Cr(VI). According to the results of the study, reduction and removal of Cr(VI) from the aqueous phase can be increased by increasing contact time. Leaching tests indicate that chromium in precipitated form is insoluble. In the tested soil material, the total amount of precipitated Cr was observed to be in the range between 280 and 890 mg/kg of soil, whereas the soluble Cr was less than 1.4 mg/kg of soil, which was most likely due to the presence of residual Cr(VI) solution in the porous soil. Nano zero-valent suspension is a very conducive to remediation of a contaminated aquifer, and the use of stable nanoparticles makes this technique successful [ 67 ]. Metals adsorbed on nanoparticles via redox reaction, co-precipitation or surface adsorption process [ 74 , 75 ]. The reactivity of iron nanoparticles based on different factors which ultimate influence on removal mechanism of, e.g. iron nanoparticles with variable oxidation states, possess different chemical characteristics as well as their mechanism of reaction with contaminants might be dissimilar as described by Tang and Lo [ 76 ].

Heterogeneous reduction reaction take place during in-situ remediation of chromium [ 77 ]. Heterogeneous reduction reaction that is followed by precipitation of reduced chromium as follow in below equations:

In another recent study, Xiao et al. [ 69 ] effectively employed plant mediated iron nanoparticles for removal of chromium, synthesised by various leaf extracts. Plant were selected on the basis of their reduction potential, i.e., selected from high to low antioxidant potential such as S. jambos (L.) Alston (SJA) extract with strong reducing ability, Oolong tea (OT) extract with moderate reducing ability and A. moluccana (L.) Willd (AMW) extract with weak reducing ability. The study shows that removal of chromium (VI) was consistent with reducing capacity of plants extracts. One millilitre of SJA-Fe NPs colloidal were able to remove 91.9% of the Cr(VI) in 5 min and 100% in 60 min. TEM image of the SJA-Fe NPs showed that NPs were spherical with diameter about to 5 nm and amorphous in nature when studied by XRD. However, this study lacks information on whether the removal of chromium of depends on reduction potential of plants or the size of nanoparticles produced by the extracts.

3.3. Wastewater Treatment

Chrysochoou et al. [ 70 ] investigated the attributes related to the transportation of iron nanoparticles synthesised with polyphenol enrich solution of green tea utilizing two granular media, refined silica sand, as well as sand-coated with aluminium hydroxide. The green tea nZVI (GT-nZVI) injection caused a rapid decline in the pH of effluent from 8.5 to 2 owing to the presence of residuary discharged Fe 3+ in the solution along with corresponding hydrolysis reactions. The elevation in the redox potential from 150 mV to 550 mV was reported despite the fact that GT-nZVI holds reducing Fe 0 . This phenomenon is the characteristic feature related to the oxidation of polyphenols available in green tea. The elevation in redox potential can be an indicator of transport of GT-nZVI in the subsurface when used as an in situ reactant.

He et al. [ 8 ] employed starch mediated bimetallic Fe/Pd nanoparticles for the degradation of TCE (trichloroethylene). Results from this study demonstrated that the starched Fe nanoparticles showed considerably less agglomeration however, higher dechlorination power than those produced without a stabilizer. At dosage of 0.1 g/L of the starched nanoparticles were able to degrade 98% of TCE within 1 h in water. Wang et al. [ 71 ] employed biosynthesised iron nanoparticles for treatment of eutrophic wastewater. This study first synthesised iron nanoparticles through a one-step room-temperature biosynthetic route using eucalyptus leaf extracts. To the best of the author’s knowledge, this is the first study to report on green tea synthesised nanomaterial utilised for remediation of eutrophic wastewater. Synthesised polydispersed iron nanoparticles employed eucalyptus leaf extract obtained from its leaf litter. Due to the presence of different phytochemicals, each with varied reducing power in the extract form, the nanoparticles were polydispersed unlike the more common practice where nanoparticles are synthesised using a chemical reducing agent. For the first time, biologically synthesised nanoparticles were used for the treatment of eutrophic wastewater. After 21 days, percentage removal of total nitrogen, total phosphorus, and COD was 71.7%, 30.4%, and 84.5%, respectively. The reason for very low phosphorus removal was assigned to the absence of precipitating agents such as calcium, magnesium or aluminium.

In another study, Wang et al. [ 72 ] utilised the leaf extracts of green tea and eucalyptus separately for the formation of iron nanoparticles (Fe NPs) and employed for the efficient removal of nitrate from wastewater. Synthesis of spheroidal iron nanoparticles (Fe NPs) was confirmed by employing characterisation techniques. A comparison study was conducted between plant-synthesised and chemically-synthesised iron materials. Green tea and eucalyptus mediated Fe NPs were able to remove 59.7% and 41.4% of nitrate from waste water, respectively, compared to a 87.6% and 11.7% removal of nitrate by nZVI and Fe 3 O 4 nanoparticles, respectively. Despite the higher removal efficiency of nZVI, the green synthesised Fe NPs were found to be more stable in nature. Reactivity of aged nZVI, green tea and eucalyptus synthesised Fe NPs was compared after being completely exposed to air for two months. Green tea and eucalyptus synthesised Fe NPs retained the same efficiency of 51.7% and 40.7%, respectively, whereas the efficacy of nZVI significantly dropped about 2.1-fold (45.4%).

3.4. Antibacterial Activity

Various studies confirm that iron nanoparticles possess good antimicrobial properties. The antibacterial effect of Tridax Procumbens synthesised iron oxide (Fe 3 O 4 ) nanoparticles was investigated by Senthil and Ramesh [ 49 ] against gram negative bacteria Pseudomonas aeruginos . Kiruba Daniel et al. [ 73 ] used the leaf extract of Dodonaea viscosa for the synthesis of Cu, ZVI and Ag nanoparticles. The reduction of iron salt (ferric chloride) to ZVI nanoparticles was observed according to recorded instantaneous changes of reaction from yellow to greenish-black at room temperature. Iron zero-valent synthesised nanoparticles showed spherical morphology with an average particle size of 27 nm. The Fourier transfrom infrared (FTIR) study confirmed that the biomolecules in D. viscosa leaves such as flavonoids perform the reduction of metals salts, and their tannins, and saponins may act as capping agents. Capping of NPs with plant biomolecules prevent the oxidation of NPs to their oxide. Antimicrobial activity of biosynthesised NPs were evaluated against human pathogens viz. gram-negative bacteria Escherichia coli , Klebsiella pneumonia , Pseudomonas fluorescens and gram-positive bacteria Staphylococcus aureus and Bacillus subtilis . These biosynthesised NPs were proved as effective antimicrobial agents against specific human pathogens.

3.5. Stabilised/Immobilised Plant Mediated FeNPs for Degradation of Pollutants

Nanoparticles have the tendency to aggregate which can reduce the effectiveness of nanoparticles. This problem can be overcome by incorporating nanoparticles on any solid support such as polymers, zeolites, silica, etc. Literature shows that plant synthesized iron nanoparticles were successfully stabilised with different materials and used for pollution remediation ( Table 4 ). Smuleac et al. [ 78 ] incorporated the Fe and bimetallic Fe/Pd nanoparticles in PVDF (polyvinylidene fluoride) membrane by green chemistry route. Green tea extract was used as a reducing agent for formation of Fe/Pd metallic nanoparticles in PVDF membranes modified by polyacrylic acid (PAA). PVDF/PAA membrane containing Fe nanoparticles was observed by SEM. An SEM image shows that the size of nanoparticles ranged from 20–30 nm with some aggregates between 80 and 100 nm. Further, reactivity of membrane supported nanoparticles was evaluated for the degradation of toxic organic pollutants known as trichloroethylene (TCE). Dechlorination of TCE was linearly increased with the increasing amount of iron (Fe) immobilised on the membrane. However, when catalytic Pd metal was added to form bimetallic Fe/Pd, the addition increased the degradation of TCE.

Polymer composite of phyto-synthesised iron nanoparticles for environmental remediation.

In another study, zerovalent iron (ZVI) nanoparticles with an average particle size of 59.08 ± 7.81 nm were synthesised by reaction of ferric nitrate with tea liquor. In addition, green zero-valent iron (ZVI) nanoparticles were stabilised on montmorillonite K10. Montmorillonite supported iron zero-valent nanoparticles were effectively employed for removal of arsenic as a heavy toxic metal. Ninety-nine per cent removal of arsenic As(III) was achieved in a reaction time of 30 min. from its solution at both low and high pH (2.75 and 11.1). Montmorillonite K10 alone removed less As(III), than the percentage of the tested montmorillonite supported nanoparticles under similar conditions of reaction [ 79 ].

Prasad et al. [ 80 ] studied the removal of arsenite(III) and arsenate(V) from aqueous solution using green synthesised iron nanoparticles. Mentha spicata L. synthesised iron nanoparticles showed absorption peaks at 360 and 430 nm confirmed by UV-Vis. Transmission electron microscope (TEM) results revealed that iron nanoparticles have core-shell structure and ranged from 20 to 45 nm in diameter. The planer reflection of selected area electron diffraction (SAED) and X-ray diffraction (XRD) analysis suggested that iron particles were crystalline and belonged to fcc (face centred cubic) type. FTIR study suggested that biomolecules or functional groups like N–H, C=O, C=C and C=N present in M. spicata extract were involved in particle formation. The efficiency of nanoparticles-chitosan composite for the removal of As(III) and As(V) was found to be 98.79% and 99.65%, respectively. The effect of extract ratio on formation of iron nanoparticles was studied by Martínez-Cabanas et al. [ 81 ]. Among chestnut tree ( Castanea sativa ), eucalyptus ( Eucalyptus globulus ), gorse ( Ulex europaeus ) and Pine ( Pinus pinaster ), eucalyptus was selected for synthesis of iron nanoparticles due to its high antioxidant property and availability. Different ratios of iron and extract were used for nanoparticles synthesis. Nanoparticles suspensions were mixed with chitosan separately and characteristics of chitosan beads were studied. Results of the study demonstrated that the iron/extract ratio not only effected on stability but also effected on magnetism behaviour of beads. However, TEM showed not any significant morphology and size difference. Chitosan encapsulated iron nanoparticles with good characteristics of stability were used for removal of arsenic by batch and column experiments for removal of arsenic. Regeneration of adsorbent suggested that green synthesised chitosan incorporated iron particles may work as an effective tool for elimination of arsenic from contaminated water.

4. Environmental Implications of Iron Nanoparticles

Despite the tremendous environmental applications of iron nanomaterials, they also present a risk when the environment comes into direct contact with these nanomaterials. Improper waste management from industries, leakage, and most important pollution remediation can cause harm—specifically in ground water and soil remediation where iron nanomaterial can transfer from one medium to another. Among the different species of iron nanoparticles, nano zero-valent iron (nZVI) is considered to be very reactive. Once zero-valent iron (Fe 0 ) used as permeable reactive barriers for in situ treatment of ground water, it undergoes to transformation in presence of contaminants as well as to exposed environment. Presence of iron NPs in environment induces many toxic impacts to microorganisms and soil fauna, directly and indirectly significant for environment. Considerable toxicological impacts of iron NPs on soil microorganisms and changes in microbial biomass can be caused by induced stress of nanoiron [ 82 , 83 ]. Antisari et al. [ 82 ] evaluated the impacts of engineered nanoparticles on soil microbial mass and observed the change in microbial mass of soil. Moreover, transcriptional and proteomic stress responses to soil bacterium Bacillus cereus by nanosized zero-valent iron (nZVI) particles were observed by Fajardo et al. [ 84 ].

Auffan et al. [ 85 ] reported the relationship between oxidation state of iron nanoparticles and cytotoxicity. For this purpose, they compared the cytotoxic impacts of nZVI and iron oxide nanoparticles (magnetite and maghemite) towards gram negative bacteria E. coli . The toxicity of nZVI was found to be higher than the other iron oxide NPs. It was thought that the toxicity was associated with oxidation of iron nanoparticles which generated the oxidative stress from reactive oxygen species (ROS). ROS includes highly unstable superoxide radicals, hydroxyl radicals and freely diffusible and relatively long-lived hydrogen peroxide, which adsorb on the cell membrane and disrupt the functioning of cell. In another study Lee et al. [ 86 ] found that nZVI exhibited strong bactericidal activity under anaerobic conditions with a linear correlation between log inactivation of E. coli and nZVI dose. The toxicity of nZVI under oxygen saturated conditions was significantly lower than under deaerated conditions, thought to be related to oxidation and formed an iron oxide layer. This phenomenon was confirmed by study of Li et al. [ 87 ] which demonstrated that complete oxidation of nZVI in aerobic conditions almost eliminated bactericidal effects. In addition, Fe(II) was found to be more toxic under deaerated conditions, suggesting that released Fe(II) from nZVI contributes to toxicity. Likewise, nZVI triggered the substantial physical disruption of cell membranes, which led to cell inactivation by penetrating the cell membrane and causing physical damage or by enhancing the biocidal effects of Fe(II).

Age and surface modification influence on toxicity behaviour of nZVI. Phenrat et al. correlated the chemical and surface properties of nZVI with toxicity. In this study, Phenrat et al. used fresh nZVI, aged nZVI (>11 months), magnetite, and polyaspartate surface-modified (SM) nZVI to mammalian cells. It was found that particle properties such as “redox” activity, sedimentation rate, and agglomeration, generated morphological changes in neuron cells and cultured rodent microglia of mammalian cells. However, surface modified nZVI showed less toxicity because of reducing particles sedimentation which ultimately limited the particle exposure to the cells. Fresh nZVI showed remarkable impacts while aged nZVI exhibited insignificant morphological changes in mitochondrial and reduced ATP levels in neuron cells [ 88 ]. Chen et al. [ 89 ] evaluated the toxic effects of three different solutions containing carboxymethyl cellulose nZVI (CMC-nZVI), nFe 3 O 4 and ferrous ion solution Fe(II) aq by exposing to early life stages of medaka fish. The CMC-nZVI solution was found to be more toxic to embryos as compared to Fe(II) aq and nFe 3 O 4 . CMC-nZVI solution was comprised of different oxidised forms of iron, generated from nZVI caused hypoxia, developmental toxicity and ROS oxidative stress in medaka embryos. It is believed that physicochemical properties of nZVI change in aqueous medium, such as chemical reactivity, particles aggregation, etc., which further influence the bioavailability or uptake of the nanoparticles and modify the toxicity behaviour of nZVI in fish.

The literature shows that the stabilised nanoparticles or capping agents does not helpful to reduce the iron oxide NPs toxicity. In one study Baumann et al. [ 90 ] functionalised the iron NPs with four different coatings: ascorbate (ASC-IONP), citrate (CIT-IONP), dextran (DEX-IONP), and polyvinylpyrrolidone (PVP-IONP) and evaluated their acute toxicity towards neonates of the water flea Daphnia magna . The highest immobilizing effect was recorded for ASC-IONP and DEX-IONP. In the presence of neonates, both ASC-IONP and DEX-IONP agglomerated or flocculated and adsorbed to the carapace and filtering apparatuses, induced high immobilisation. Lower immobilisation was found for CIT-IONP. Furthermore, incomplete ecdysis occurred at high concentrations of ASC-IOPN, DEX-IOPN, and CIT-IONP. PVP-IONP did not induce any negative effect, although high quantities were visibly ingested by the daphnids. PVP-IONP showed highest colloidal stability without any agglomeration, adsorption, or dissolution. It was thought that hydrodynamic diameter or the kind of stabilizing forces did not cause toxicity in daphnids, however the factors like colloidal stability and release of ions from the material, generated ROS in daphnids.

Green alga is an ecological indictor and represents aquatic ecosystem health. Toxicity of superparamagnetic iron oxide nanoparticles (SPION) has been investigated towards green algae Chlorella vulgaris. C. vulgaris cells were exposed with three iron oxides NPs suspensions with different chemical concentrations. SPION posed substantial toxicity, disrupted the photochemical activity of algal cells by inducing oxidative stress, and inhibiting the cell division [ 91 ].

Lethal effects of iron nanoparticles towards aquatic organisms have been documented by different researchers. Li et al. [ 92 ] investigated the effects of nZVI on antioxidant enzymatic activities and lipid peroxidation in Medaka ( Oryzias latipes ). Results showed that nZVI caused a disturbance in the oxidative defence system for embryos and adults, as well as oxidative damage in embryos with some observed effects at concentrations as low as 0.5 mg/L. Adult fish also showed antioxidant balance disruption although they were able to recover afterwards. Furthermore, histopathological changes and morphological alterations were observed in gills and intestine of adult fish. Remya et al. [ 93 ] evaluated the chronic toxicity effects of iron oxide (Fe 2 O 3 ) nanoparticles (500 mg/L) on certain haematological, ionoregulatory and gill Na + /K + ATPase activity of an Indian major carp, Labeo rohita . As compared to control groups, significant increase in haemoglobin (Hb) content, red blood cell (RBC) count and haematocrit (Ht) value was noticed. Fe 2 O 3 nanoparticles also caused some variations in ionoregulation resulting in hyponatremia (Na + ), hypochloremia (Cl − ) and hypokalemia (K + ). A biphasic trend in gill Na + /K + ATPase activity was also noticed. Taze et al. [ 94 ] observed the oxidative responses of the mussel Mytilus galloprovincialis after exposure to iron oxide NPs and to iron oxide NPs incorporated into zeolite for 1, 3 and 7 days. Results showed that both effectors induced changes on animal physiology by causing oxidative stress in haemocytes of exposed mussels compared to control animals. Toxicity effects were observed by the significant increase in reactive oxygen species (ROS) production, lipid peroxidation, protein carbonylation, ubiquitin conjugates and DNA damage.

Blinova et al. [ 95 ] evaluated the toxicity of nanosized and bulk iron oxide nanoparticles on D. magna. No significant difference was observed in biological effects of both sized nanoparticles of magnetite. Although, iron oxide NPs induced very low toxicity (EC 50 < 100 ppm) to D. magna and duck weed Lemna minor in the standard acute assays. It was observed that at acutely subtoxic magnetite concentrations (10 and 100 ppm), the number of neonates hatched from D. magna ephippia was decreased.

In addition to this, secondary environmental impacts of nano zero-valent iron (nZVI) have been investigated in soil organisms. Few studies reveal that iron NPs including nZVI and magnetic nanoparticles have positive effect on soil microbial community and facilitate the carbon and nitrogen cycling in soil. Iron oxide magnetic nanoparticles (IOMNPs) could potentially stimulate some bacterial growth and change the soil bacterial community structure, although bacterial abundance was not change. Meanwhile, soil urease and invertase activities significantly increased under IOMNPs amendment, which could be a consequence of the changes in the bacterial community [ 96 ]. El-Temsah and Joner [ 97 ] evaluated the ecotoxicological effects of nZVI coated with carboxymethyl cellulose on two species of earthworms, Eisenia fetida and Lumbricus rubellus . Earthworms were exposed to different nZVI concentrations ranging from 0 to 2000 mg nZVI kg·soil −1 . Physical changes such as weight changes and mortality were observed for both species of earthworms at concentrations 500 mg·kg −1 soil. Reproduction was affected also at 100 mg nZVI·kg −1 . However toxicity effects of aged soil nZVI were significantly reduced as compared to non-aged soils.

Fajardo et al. [ 98 ] studied the toxicity impacts of residual aged nZVI on metal contaminated soil. Heavy metal (Pb, Zn) polluted soils properties were evaluated after a leaching experiment. No negative effects on physico-chemical soil properties were observed after aged nZVI exposure. It was found that aged nZVI had negative effects on soil properties and NPs treatment increase Fe availability to soil. Moreover, toxic impacts of aged nZVI were related to metal contaminants of soil. However, Pb-nZVI soil showed changes in biodiversity, enhanced oxidative stress and Pb toxicity. Increased biological activity and decreased Zn toxicity were observed in Zn-nZVI soil. Canivet et al. [ 99 ] reported that iron nanoparticles had no significant cytotoxicity impacts on bryophytes ( Physcomitrella patens ). Similar results were observed in another study iron nanoparticles were exposed to seeds, iron nanoparticles could not show any detrimental impacts on seed germination at lower concentration of iron nanoparticles (0–5000 mg/L) [ 100 ]. Oxidative stress in plants and animal cells has been studied by many researchers. Studies show that many factors affect the behaviour of iron nanoparticles when they are released into the environment. Although the literature survey revealed that the presence of iron nanoparticles in soil exhibits less cytotoxicity in plants and can have positive impacts in plant germination, this scenario is not applicable to all environmental conditions due to the variation in soil types, concentration of iron nanoparticles used, and the chemical composition of NPs [ 99 , 100 ].

To combat the toxicological issues, research has advanced production of green nanomaterials, and studies have revealed that biosynthesised nanoparticles are less toxic than engineered nanoparticles [ 101 , 102 ]. In the case of biosynthesised iron nanoparticles, Nadagouda et al. [ 41 ] studied the toxic effects of phyto-synthesised nanomaterial on human keratinocyte cell. The biocompatibility of nZVI synthesised using green tea and borohydride as the reducing agent was assessed using methyl tetrazolium (MTS) and lactate dehydrogenase (LDH) assay by exposing cell lines to nZVIs for 24–48 h. LDH leakage increased with an increase in particle size, thereby stressing the cellular membrane. Hence, nZVI was synthesised using green tea since it is much smaller in size and has been shown to be nontoxic to human keratinocytes when compared to nanoparticles synthesised using the borohydride reduction process. Similarly, in another study Markova et al. [ 40 ] evaluated the impacts of plant-mediated iron nanoparticles on organisms have ecological importance including cyanobacterium ( Synechococcus nidulans ), green alga ( Pseudokirchneriella subcapitata ), and invertebrate organisms ( Daphnia magna ). The results of a toxicological assay showed a negative impact of green tea synthesised iron nanoparticles on cyanobacterium ( S. nidulans ), green alga ( P. subcapitata ), and invertebrate ( D. magna ) [ 103 ]. Above studies indicate that biosynthesised NPs are safe to environment and human beings, however in the literature, there is lack of reports concerning the toxicity of green synthesised iron oxide nanoparticles.

5. Conclusions and Future Perspective

This review focuses the production of iron nanomaterials via various green methods and their potential for remediation of environmental pollutants. The effort is made to highlight the various green agents for the synthesis of iron nanoparticles such as polymers, amino acids, bacteria, fungi, plant extracts, etc., and their reaction pathways to some extent. Moreover, this review discusses that particle size, morphology and other properties relates with the properties of materials, procedures and protocols. Literature shows that several plants and plant related materials have been exploiting for facile synthesis of iron nanoparticles, which proved to be good catalyst for widespread environmental application. Thus, plant materials look more feasible as agents for production of iron nanomaterials due to its environmentally friendly characteristics and economic value as an alternative to the large-scale production of nanoparticles. However, the mechanism has not yet been clearly described and there is need to explore the phytochemistry behind the synthesis of iron nanoparticles.

To achieve the sustainability of nanomaterial synthesis, more research is needed to explore more local and commonly available resources for the production of iron nanomaterials. Understanding the biochemical mechanisms involved in nanoparticle synthesis is a prerequisite to the success of any new methodology, and any solution must be economically competitive with conventional methods. Local resources should be utilised as their development will ultimately reduce the cost. In future research, more detailed study will provide a clear description of biomolecules and their role in mediating the synthesis of nanoparticles. The goal is to influence the rate of synthesis and improve nanoparticle stability. Moreover, research should be conducted to steer the production of iron nanoparticles toward increased reactivity to enhance environmental pollution degradation with minimum ecotoxicological impacts. In comparison to engineered nanoparticles, few studies confirm that biosynthesised nanoparticles are less toxic. In addition, a comprehensive risk assessment of green fabricated Fe NPs should be performed in which fate, transport, aggregation, dissolution and kinetics in processing of the nanoparticles is considered. In conclusion, green nanotechnology processes, as described in this paper, provide a strong foundation for the production of a variety of biochemical or functionalised nanoparticles that can serve as building blocks in the development of new products that can be applicable in environmental restoration sectors.

Acknowledgments

This research was partially supported by the U.S. National Science Foundation (NSF Grant No. CBET-1235166).

Abbreviations

Authors Contribution

Sadia Saif wrote the manuscript under the guidance of Arifa Tahir and Yongsheng Chen. Additionally, manuscript was corrected and edited by Yongsheng Chen.

Conflicts of Interest

The authors declare no conflict of interest.

• Research note
• Open access
• Published: 25 April 2022

Green synthesis and characterization of iron-oxide nanoparticles using Moringa oleifera: a potential protocol for use in low and middle income countries

• Henry Fenekansi Kiwumulo 1 ,
• Haruna Muwonge 1 , 4 ,
• Charles Ibingira 2 ,
• Michael Lubwama 3 ,
• John Baptist Kirabira 3 &
• Robert Tamale Ssekitoleko   ORCID: orcid.org/0000-0002-5898-1812 1  

BMC Research Notes volume  15 , Article number:  149 ( 2022 ) Cite this article

12k Accesses

50 Citations

Metrics details

Green synthesized iron(III) oxide (Fe 3 O 4 ) nanoparticles are gaining appeal in targeted drug delivery systems because of their low cost, fast processing and nontoxicity. However, there is no known research work undertaken in the production of green synthesized nano-particles from the Ugandan grown Moringa Oleifera (MO). This study aims at exploring and developing an optimized protocol aimed at producing such nanoparticles from the Ugandan grown Moringa.

While reducing ferric chloride solution with Moringa oleifera leaves, Iron oxide nanoparticles (Fe 3 O 4 -NPs) were synthesized through an economical and completely green biosynthetic method. The structural properties of these Fe 3 O 4 -NPs were investigated by Ultra Violet–visible (UV–Vis) spectrophotometry, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). These nanoparticles exhibited UV–visible absorption peaks at 225 nm (nm) for the sixth dilution and 228 nm for the fifth dilution which indicated that the nanoparticles were photosensitive and the SEM study confirmed the spherical nature of these nanoparticles. The total synthesis time was approximately 5 h after drying the moringa leaves, and the average particle size was approximately 16 nm. Such synthesized nanoparticles can potentially be useful for drug delivery, especially in Low and Middle Income Countries (LMICs).

Introduction

There are quite limited green synthesis studies of Fe 3 O 4 -NPs via biological routes and their use in the biomedical field, especially in LMICs [ 1 ]. Table 1 indicates the size and morphology of magnetite crystals which play an important role in influencing magnetite's properties [ 2 ]. Interestingly, Fe 3 O 4 -NPs are biocompatible, biodegradable, and potentially nontoxic to humans [ 3 ]. These properties contribute to the versatility of Fe 3 O 4 -NPs and show great potential in future biomedical applications such as targeted drug delivery, antibacterial, tissue engineering, and so on. In this regard, numerous Fe 3 O 4 -NP synthesis methods, for example, coprecipitation, the sol–gel method [ 4 ], hydrothermal synthesis [ 5 ], solid-state synthesis [ 6 ], flame spray synthesis [ 7 ], thermal decomposition [ 5 ], and solvothermal methods [ 8 ], have been adopted to produce nanoparticles with desired properties. However, such methods have had a number of limitations, including high production costs, toxic chemicals, and the production of hazardous byproducts [ 9 , 10 , 11 , 12 ]. This has necessitated research in green synthesis approaches in an effort to address the above issues caused by these conventional methods [ 13 ]. Green synthesis has many advantages, such as being simple, having fast manufacturing procedures, having lower production costs, and producing less waste [ 14 ].

Medicinal plants can easily be conjugated with Fe 3 O 4 -based nanoparticles to produce drug delivery applications [ 51 ]. This is because of their ability to produce excellent formulations that yield to multiple biological signaling pathways. Among the many plants that have inspired green synthesis is Moringa oleifera (MO) [ 52 ]. MO was initially used in the treatment of inflammation, cancer, bacterial/viral infections and hyperglycaemia because of its high bioactive and antioxidant compounds. MO is excellently rich in such polyphenols and provides a wonderful synthesis agent for the necessary nanoparticles [ 53 ]. Regarding anticancer potential, Moringa oleifera (MO) has the ability to fight various cancers [ 54 ]. However, it seems challenging to produce such Fe 3 O 4 -based nanoparticles using MO.

The aim of this study is therefore to develop an appropriate protocol for green biosynthesis and characterization of Fe 3 O 4 -NPs using MO leaves given the multiple drug delivery applications from such particles. It was hypothesized that such green synthesized nanoparticles may greatly be applicable in targeted drug delivery especially during cancer treatment. Based on the researchers’ knowledge, this is the first attempt to use Ugandan grown MO for green synthesis and characterization of iron oxide nanoparticles.

Ferrous iron (III) chloride (FeCl 3 ) was of analytical grade and purchased from Smakk International Ltd., a laboratory supplies company in Kampala. This chloride was additionally used without further purification and was dissolved into deionized (DI) water for all the synthesis procedures. MO leaves were collected from a Moringa plantation found in Eastern Uganda.

Preparation of MO leaves into MO extract solution

MO leaves were hand sorted and dried under room temperature for 72 h as per Fig.  1 . 30 g of the dried leaves were then measured using a sartorius measuring scale (Max 5200, Germany) and ground using a silver crest powder grinder (SC-1880) at a rotating speed of 28,000 revolutions per minute for 5 min. 10 g of Moringa powder was mixed with 100 ml of DI water in an Erlenmeyer flask and heated at 80 °C while stirring using a magnetic stirrer for 1 h at a rate of 200 revolutions/per minute. The heated moringa solution was allowed to cool for 3 h and then filtered initially using cotton wool and then nylon filter to obtain a fine moringa solution, as shown in Fig.  1 f. All this work was done from the Research Center for Tropical Diseases and Vector Control (RTC) of Makerere University College of Veterinary, Animal Resources and Biosecurity (COVAB).

The extraction process of moringa solution from moringa leaves a Sorting and cleaning b Weighing the sample c Grinded powder sample d Heating the sample e Cotton wool filtered MO extract f Nylon filtered MO extract g Fe3Cl4 solution h MO extract i MO-Fe3Cl4 solution

Preparation of the Moringa oleifera-iron(III) chloride (MO-Fe 3 Cl 4 ) solution

Following a protocol from Aisida et al. [ 55 ], 0.6 M of Iron(III) chloride solution was prepared by mixing ferrous Iron(III)chloride with 100 ml of DI water and shaken to fully dissolve for approximately 15 min. 80 ml of this iron(III)chloride solution was mixed with 20 ml of the MO solution to form the MO-Fe 3 Cl 4 solution. Deviating a bit from this protocol, this solution was placed in a water bath at 60 °C and was allowed to run for 4 h to activate the phytochemicals. This solution was cooled for 2 h at room temperature and thereafter stored in a refrigerator at 4 °C for future use.

Preparation of Moringa oleifera-Iron(III)chloride (MO-Fe 3 Cl 4 ) dilutions for UV–Vis analysis

Different MO-Fe 3 Cl 4 solutions were prepared using a serial dilution procedure to clearly space and characterize the suspected particles using a UV–visible spectrometer [ 56 , 57 ]. Six dilutions were obtained with the first one obtained by mixing 2 ml of DI water into 1 ml of MO-Fe 3 Cl 4 solution. The second dilution was obtained by mixing 1 ml of the first dilution with 2 ml of DI water, the third was obtained by mixing 1 ml of the second dilution with 2 ml of DI water, the fourth was obtained by mixing 1 ml of the third dilution with 2 ml of DI water, the fifth was obtained by mixing 1 ml of the fourth dilution with 2 ml of DI water and finally the sixth was obtained by mixing 1 ml of the fifth dilution with 2 ml of DI water. The DI water graph was used as a control graph to clearly isolate the peaks obtained from this solvent in comparison with those obtained from the MO-Fe 3 Cl 4 solution. Farther dilutions never showed any difference in the UV–Vis graph, hence ending with the fifth dilution.

Characterization of the nanoparticles

The synthesized nanoparticles were characterized by using a UV–Vis, XRD, SEM, and EDX. The optical properties of the synthesized nanoparticles were examined and confirmed using a double beam UV–Vis (Jenway 6715, UK) using a spectral range of 200–400 nm from Makerere University’s RTC lab. A powder XRD employing a Bruker AXS diffractometer, (Bruker, Germany) and fitted with Cu-Ka radiation (λKα 1  = 1.5406 Å) from 2θ = 0.5°–130°, with increments of Δ2ϑ: (0.034°), voltage of 40 kV, current of 40 mA, power of 1.6KW, and counting time of 0.5 s/step was used to analyze approximately 500 mg of green synthesized Fe 3 O 4 -NPs powder. This was done from the Materials Research Department (MRD), iThemba LABs, Cape Town in South Africa. The generated data were analysed by OriginPro, and the resultant peaks and two theta values were compared with the standard Fe 3 O 4 -NP values from the International Center for Diffraction Data (ICDD) database. The structural morphology of the prepared nanoparticles was determined by a ZEISS (Gemini 1, Germany) scanning electron microscope and EDX from Makerere University’s Mechanical Engineering Department at a working distance (WD) of 7.9 mm and an accelerating voltage of 10 kV under vacuum conditions.

Results and discussion

The results below indicate the characteristics of the produced nanoparticles.

UV–Vis analysis

The formation of nanoparticles was evidenced by the appearance of an instantaneous dark black color change from brown in the solution, as shown in Fig.  1 i. This formation was due to a variety of plant biomolecules (polyphenols), which played a major role in the reduction of metal ions and sufficiently stabilized the Fe 3 O 4 -NPs. Phytochemicals bound to the surface of these nanoparticles are rich in hydrophilic hydroxyl groups that allow the NPs to disperse and distribute homogenously in aqueous solutions [ 58 ]. Thus, after the reaction, it can be seen that the UV spectra of the fabricated nanoparticles had absorption bands at lower concentrations than at higher concentrations.

The UV–Vis absorption peaks (225 nm and 297 nm) are also attributed to the presence of alkaloids, phenolic acids, flavonoids, tannins, terpenoids and carbohydrates in the MO aqueous extract. The DI water and the sixth dilution clearly indicate both peaks compared to other graphs [ 59 ]. This was evidenced by a 268 nm absorption peak that was produced by the DI water graph, confirming the occurrence of a synthesis process.

Additionally, the UV–Vis results showed a maximum absorption peak at 225 nm for the sixth dilution and 228 nm for the fifth dilution, followed by the peak at 297 nm for both dilutions. This could be due to the excitation of nanoparticles from the ground to the excited state [ 60 ]. The high concentration of leaf extract enhanced the phytochemical content of the extract, which reduced the precursor quickly, leading to rapid nanoparticle formation that enhanced the absorbance value, as shown in Fig.  2 a [ 61 ]. Therefore, the UV–Vis analysis concluded that Fe 3 O 4 -NPs had an intense absorbance at ∼ 300 nm, hence indicating the photosensitivity of the synthesized particles in the UV region [ 62 ].

a UV–Vis graphs showing different dilutions b XRD graph for the Iron-oxide biosynthesized Fe 3 O 4 -NPs c SEM image for the iron (III) chloride precursor d XRD for the iron (III) chloride precursor e SEM image for the Iron-oxide biosynthesized Fe 3 O 4 -NPs f XRD for the Iron-oxide biosynthesized Fe 3 O 4 -NPs

XRD analysis

XRD analysis generated ten peaks for the biosynthesized Fe 3 O 4 -NPs positioned at 2θ angles of 30.2°, 35.5°, 43.2°, 53.8°, 57.3°, 62.95°, 69.0°, 71.4°, 74.3°, and 78.1°. The observed lattice spacings at 30.2°, 35.5°, 43.2°, 53.8°, and 57.3° matched well with the (220), (311), (400), (422), and (511) planes of Fe 3 O 4 crystals (Fig.  2 b). The crystal structure data was in close agreement with the reported data and can be assigned to the magnetite phase of iron oxide [ 63 ]. This XRD pattern for magnetic nanoparticles is cross referenced with ICDD—International Centre for Diffraction Data (ICDD) file number: 00–019-0629. The peak intensity ranged from 240 to 1,400 arbitrary units for the synthesized Fe 3 O 4 -NPs.

Scanning electron microscope and energy dispersive X-ray analysis

Figure  2 c never indicated the synthesized Fe 3 O 4 -NPs as compared to Fig.  2 e. This clearly confirmed that such nanoparticles were a reaction result between MO and Iron(III) chloride precursor. Fe 3 O 4 -NPs exhibited a granular, homogenous, spherical-shaped structure with an average diameter of approximately 16 nm. Given the unique atomic structure of each element, EDX was additionally used to provide information about the chemical composition of each element as it interacts between the X-rays and the compound being investigated. Therefore, when this analysis was carried out, the X-rays reflected off the iron compound to give peak amplitudes that helped to identify the elements present in the compound being studied. The peak amplitude of iron started from approximately 0.66 to 7 keV, as shown by Fig.  2 d and f which confirmed the presence of the iron elements in the compounds using EDX [ 64 ]. The results also demonstrated the high percentage of iron present in the particles, as the EDX spectra revealed the presence of iron peaks in three different areas (0.66, 0.68 and 7.0). Energy dispersive X-ray spectroscopy (EDX) was also used to confirm iron oxide nanoparticle formation and obtain more structural details about the suspension. There were several peaks of Fe with other elements, such as sodium, aluminium and chlorine, thus indicating the ability for organic materials to be used as capping agents.

Energy dispersive X-ray analysis

EDX analysis further provided the qualitative and quantitative status of the elements, which may have affected the fabrication of the NPs. This analysis showed that the EDX spectrum contained intense peaks of Cl and Fe in addition to minor peaks of Na and Al. The Fe and Cl peaks might have originated from the FeCl 3 precursors used in the fabrication of these nanoparticles. The Na and Al peaks could mainly have been due to the polyphenol groups or other sodium/aluminum-containing biomolecules present in the MO leaf extract. The higher percentages of Cl indicated the plant biomolecules presence in the metal ions reduction and stabilization of the nanoparticles. These values might also be helpful in observing the atomic content on the surface and near the surface region of the produced nanoparticles. Such nanoparticles can potentially be used in cancer [ 65 ], bacterial [ 66 ] and viral [ 67 ] treatment mechanisms that greatly affect LMICs.

A novel green synthesis of iron oxide nanoparticles using Ugandan grown MO has been demonstrated. This first time trial of nanoparticle formulation has been confirmed by SEM to have a spherical shape with a 16 nm particle size. Given no requirements for extra surfactants or reductants, this method can serve as a simple and eco-friendly protocol for use in LMICs.

Limitations

The following studies would have confirmed our results better but could not be done due to limited resources: 1. Fourier transform infrared (FTIR) analysis of the nanoparticles, 2. Vibrating sample magnetometry studies, 3. Cancerous cell viability studies.

Availability of data and materials

The raw data analysed during the current study is available from the corresponding author on reasonable request.

Abbreviations

• Moringa oleifera

Low- and middle-income countries

Iron (III) Oxide

NPs Iron (III) Oxide nanoparticles

Ultraviolet visible

Scanning electron microscope

• X-ray diffraction

Energy dispersive X-ray

Nanoparticles

Working distance

Magnetic resonance imaging

Research center for tropical diseases and vector control

International center for diffraction data

Fourier transform infrared

Jegadeesan GB, Srimathi K, Santosh Srinivas N, Manishkanna S, Vignesh D. Green synthesis of iron oxide nanoparticles using terminalia bellirica and moringa oleifera fruit and leaf extracts: antioxidant, antibacterial and thermoacoustic properties. Biocatal Agric Biotechnol. 2019. https://doi.org/10.1016/j.bcab.2019.101354 .

Article   Google Scholar  

Zhang L, Dong WF, Sun HB. Multifunctional superparamagnetic iron oxide nanoparticles: design, synthesis and biomedical photonic applications, nanoscale. Royal Soc Chem. 2013. https://doi.org/10.1039/c3nr01616a .

Wahajuddin AS. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers. Int J Nanomedicine. 2012;7:3445–71.

Article   CAS   PubMed   PubMed Central   Google Scholar  

Lemine OM, Omri K, Zhang B, El Mir L, Sajieddine M, Alyamani A, et al. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties. Superlattices Microstruct. 2012;52(4):793–9.

Article   CAS   Google Scholar  

Chin SF, Suh C, Pang C, Tan H. Green synthesis of magnetite nanoparticles (via thermal decomposition method) with controllable size and shape. Environ Sci. 2011;2(3):299–302.

CAS   Google Scholar  

Li J, Zheng L, Cai H, Sun W, Shen M, Zhang G, et al. Polyethyleneimine—mediated synthesis of folic acid-targeted iron oxide nanoparticles for invivo tumor MR imaging. Biomaterials. 2013;34(33):8382–92.

Article   CAS   PubMed   Google Scholar  

Paiva DL, Andrade AL, Pereira MC, Fabris JD, Domingues RZ, Alvarenga ME. Novel protocol for the solid–state synthesis of magnetite for medical practices. Hyperfine Interact. 2015;232(1–3):19–27.

Luo Y, Yang J, Yan Y, Li J, Shen M, Zhang G, et al. RGD-functionalized ultrasmall iron oxide nanoparticles for targeted T1-weighted MR imaging of gliomas. Nanoscale. 2015;7(34):14538–46.

Jagwani D, Hari KP. Nature’s nano-assets: Green synthesis, characterization techniques and applications–a graphical review. Mater Today Proc. 2021;46:2307–17.

Ahmed SF, Mofijur M, Rafa N, Chowdhury AT, Chowdhury S, Nahrin M, et al. Green approaches in synthesising nanomaterials for environmental nanobioremediation: technological advancements, applications, benefits and challenges. Environ Res. 2021. https://doi.org/10.1016/j.envres.2021.111967 .

Article   PubMed   PubMed Central   Google Scholar  

Yew YP, Shameli K, Miyake M, Ahmad Khairudin NBB, Mohamad SEB, Naiki T, et al. Green biosynthesis of superparamagnetic magnetite Fe3O4 nanoparticles and biomedical applications in targeted anticancer drug delivery system: a review. Arabian J Chem. 2020. https://doi.org/10.1016/j.arabjc.2018.04.013 .

Hao R, Li D, Zhang J. Green Synthesis of iron nanoparticles using green tea and its removal of hexavalent chromium. Nanomaterials. 2021. https://doi.org/10.3390/nano11030650 .

Mallapragada SK, Brenza TM, McMillan JEM, Narasimhan B, Sakaguchi DS, Sharma AD, et al. Enabling nanomaterial, nanofabrication and cellular technologies for nanoneuromedicines. Nanomedicine. 2015. https://doi.org/10.1016/j.nano.2014.12.013 .

Article   PubMed   Google Scholar  

Patra JK, Baek KH. Green nanobiotechnology: factors affecting synthesis and characterization techniques. J Nanomaterials. 2014. https://doi.org/10.1155/2014/417305 .

Venkateswarlu S, Rao YS, Balaji T, Prathima B, Jyothi NVV. Biogenic synthesis of Fe3O4 magnetic nanoparticles using plantain peel extract. Mater Lett. 2013;100:241–4.

Venkateswarlu S, Kumar BN, Prathima B, SubbaRao Y, Jyothi NVV. A novel green synthesis of Fe 3 O 4 magnetic nanorods using punica granatum rind extract and its application for removal of Pb(II) from aqueous environment. Arab J Chem. 2019;12(4):588–96.

Yuvakkumar R, Hong SI. Green synthesis of spinel magnetite iron oxide nanoparticles. Adv Mat Res. 2014. https://doi.org/10.4028/www.scientific.net/AMR.1051.39 .

Venkateswarlu S, Yoon M. Rapid removal of cadmium ions using green-synthesized Fe3O4 nanoparticles capped with diethyl-4-(4 amino-5-mercapto-4H-1,2,4-triazol-3-yl)phenyl phosphonate. RSC Adv. 2015;5(80):65444–53.

Venkateswarlu S, Yoon M. Surfactant-free green synthesis of Fe3O4 nanoparticles capped with 3,4-dihydroxyphenethylcarbamodithioate: Stable recyclable magnetic nanoparticles for the rapid and efficient removal of Hg(II) ions from water. Dalt Trans. 2015;44(42):18427–37.

Bano S, Nazir S, Nazir A, Munir S, Mahmood T, Afzal M, et al. Microwave-assisted green synthesis of superparamagnetic nanoparticles using fruit peel extracts: surface engineering, T2relaxometry, and photodynamic treatment potential. Int J Nanomedicine. 2016;10(11):3833–48.

Kumar B, Smita K, Cumbal L, Debut A. Biogenic synthesis of iron oxide nanoparticles for 2-arylbenzimidazole fabrication. J Saudi Chem Soc. 2014;18(4):364–9.

Ahmed MJK, Ahmaruzzaman M, Bordoloi MH. Novel averrhoa carambola extract stabilized magnetite nanoparticles: a green synthesis route for the removal of chlorazol black e from wastewater. RSC Adv. 2015;5(91):74645–55.

Bahadur A, Saeed A, Shoaib M, Iqbal S, Bashir MI, Waqas M, et al. Eco-friendly synthesis of magnetite (Fe3O4) nanoparticles with tunable size: dielectric, magnetic, thermal and optical studies. Mater Chem Phys. 2017;1(198):229–35.

Sathishkumar G, Logeshwaran V, Sarathbabu S, Jha PK, Jeyaraj M, Rajkuberan C, et al. Green synthesis of magnetic Fe3O4 nanoparticles using couroupita guianensis aubl. Fruit extract for their antibacterial and cytotoxicity activities. Artif cells, nanomed Biotechnol. 2018;46(3):589–98.

Awwad AM, Salem NM. A green and facile approach for synthesis of magnetite nanoparticles. Nanosci Nanotechnol. 2013. https://doi.org/10.5923/j.nn.20120206.09 .

Senthil M, Ramesh C. Biogenic Synthesis of Fe3O4 Nanoparticles Using Tridax Procumbens Leaf Extract and Its Antibacterial Activity on Pseudomonas aeroginosa. Dig J Nanomater. Bios. 2012;7:1655-60.

Google Scholar  

Basavegowda N, Somai Magar KB, Mishra K, Lee YR. Green fabrication of ferromagnetic Fe3O4 nanoparticles and their novel catalytic applications for the synthesis of biologically interesting benzoxazinone and benzthioxazinone derivatives. New J Chem. 2014;38(11):5415–20.

Latha N, Gowri M. Bio Synthesis and Characterisation of Fe 3 o 4 Nanoparticles using caricaya papaya leaves extract. International journal of science and research. www.ijsr.net . Accessed Jun 22 2021.

Atarod M, Nasrollahzadeh M, Sajadi SM. Green synthesis of a Cu/reduced graphene oxide/Fe3O4 nanocomposite using Euphorbia wallichii leaf extract and its application as a recyclable and heterogeneous catalyst for the reduction of 4-nitrophenol and rhodamine B. RSC Adv. 2015;5(111):91532–43.

Xiao L, Mertens M, Wortmann L, Kremer S, Valldor M, Lammers T, et al. Enhanced in vitro and in vivo cellular imaging with green tea coated water-soluble iron oxide nanocrystals. ACS appl mater interfaces. 2015;7(12):6530–40. https://doi.org/10.1021/am508404t .

Patra JK, Ali MS, Oh IG, Baek KH. Proteasome inhibitory, antioxidant, and synergistic antibacterial and anticandidal activity of green biosynthesized magnetic Fe3O4 nanoparticles using the aqueous extract of corn (Zea mays L.) ear leaves. Artif Cells Nanomed Biotechnol. 2017;45(2):349–56.

Rajendran SP, Sengodan K. Synthesis and characterization of zinc oxide and iron oxide nanoparticles using sesbania grandiflora leaf extract as reducing agent. J Nanosci. 2017;2017:1–7.

Kumar B, Garcia M, Murakami JL, Chen C-C. Exosome-mediated microenvironment dysregulation in leukemia. Biochim biophys acta mol cell res. 2016;1863(3):464–70.

Sirdeshpande KD, Sridhar A, Cholkar KM, Selvaraj R. Structural characterization of mesoporous magnetite nanoparticles synthesized using the leaf extract of calliandra haematocephala and their photocatalytic degradation of malachite green dye. Appl Nanosci. 2018;8(4):675–83.

Kanagasubbulakshmi S, Kadirvelu K. Green synthesis of Iron oxide nanoparticles using lagenaria siceraria and evaluation of its antimicrobial activity. Def Life Sci J. 2017;2(4):422.

Narayanan S, Sathy BN, Mony U, Koyakutty M, Nair SV, Menon D. Biocompatible magnetite/gold nanohybrid contrast agents via green chemistry for MRI and CT bioimaging. ACS Appl Mater Interfaces. 2012;4(1):251–60.

Venkateswarlu S, Natesh Kumar B, Prasad CH, Venkateswarlu P, Jyothi NVV. Bio-inspired green synthesis of Fe3O4 spherical magnetic nanoparticles using syzygium cumini seed extract. Phys B Condens Matter. 2014;15(449):67–71.

Cai Y, Shen Y, Xie A, Li S, Wang X. Green synthesis of soya bean sprouts-mediated superparamagnetic Fe 3O4 nanoparticles. J Magn Magn Mater. 2010;322(19):2938–43.

Ngernpimai S, Thomas C, Maensiri S, Siri S. Stability and cytotoxicity of well–dispersed magnetite nanoparticles prepared by hydrothermal method. Adv Mat Res. 2012. https://doi.org/10.4028/www.scientific.net/AMR.506.1 .

Phumying S, Labuayai S, Thomas C, Amornkitbamrung V, Swatsitang E, Maensiri S. Aloe vera plant–extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles. Appl Phys A Mater Sci Process. 2013;111(4):1187–93.

Mahdavi M, Namvar F, Bin AM, Mohamad R. Green biosynthesis and characterization of magnetic iron oxide (Fe 3O4) nanoparticles using seaweed (Sargassum muticum) aqueous extract. Molecules. 2013;18(5):5954–64.

Yew YP, Shameli K, Miyake M, Kuwano N, Bt Ahmad Khairudin NB, Bt Mohamad SE, et al. Green synthesis of magnetite (Fe3O4) nanoparticles using seaweed extract. Nanoscale Res Lett. 2016. https://doi.org/10.1186/s11671-016-1498-2 .

El-Kassas HY, Aly-Eldeen MA, Gharib SM. Green synthesis of iron oxide (Fe3O4) nanoparticles using two selected brown seaweeds: characterization and application for lead bioremediation. Acta Oceanol Sin. 2016;35(8):89–98. https://doi.org/10.1007/s13131-016-0880-3 .

Niraimathee VA, Subha V, Ernest Ravindran RS, Renganathan S. Green synthesis of iron oxide nanoparticles from mimosa pudica root extract. Int J Environ Sustain Dev. 2016;15(3):227–40.

Buazar F, Baghlani-Nejazd MH, Badri M, Kashisaz M, Khaledi-Nasab A, Kroushawi F. Facile one-pot phytosynthesis of magnetic nanoparticles using potato extract and their catalytic activity. Starch–Stärke. 2016;68(7–8):796–804. https://doi.org/10.1002/star.201500347 .

Lunge S, Singh S, Sinha A. Magnetic iron oxide (Fe3O4) nanoparticles from tea waste for arsenic removal. J Magn Magn Mater. 2014;1(356):21–31.

Khandanlou R, Bin Ahmad M, Shameli K, Kalantari K. Synthesis and characterization of rice straw/Fe3O4 nanocomposites by a quick precipitation method. Molecules. 2013;18(6):6597–607.

Khataee A, Kayan B, Kalderis D, Karimi A, Akay S, Konsolakis M. Ultrasound-assisted removal of Acid Red 17 using nanosized Fe3O4-loaded coffee waste hydrochar. Ultrason Sonochem. 2017;1(35):72–80.

Khan MY, Mangrich AS, Schultz J, Grasel FS, Mattoso N, Mosca DH. Green chemistry preparation of superparamagnetic nanoparticles containing Fe3O4 cores in biochar. J Anal Appl Pyrolysis. 2015;1(116):42–8.

Horst MF, Coral DF, Fernández van Raap MB, Alvarez M, Lassalle V. Hybrid nanomaterials based on gum Arabic and magnetite for hyperthermia treatments. Mater Sci Eng C. 2017. https://doi.org/10.1016/j.msec.2016.12.035 .

Anand K, Tiloke C, Phulukdaree A, Ranjan B, Chuturgoon A, Singh S, et al. Biosynthesis of palladium nanoparticles by using Moringa oleifera flower extract and their catalytic and biological properties. J Photochem Photobiol B Biol. 2016;165:87–95.

Anwar F, Latif S, Ashraf M, Gilani AH. Moringa oleifera: A food plant with multiple medicinal uses. Phyther Res. 2007;21(1):17–25.

Tiloke C, Anand K, Gengan RM, Chuturgoon AA. Moringa oleifera and their phytonanoparticles: potential antiproliferative agents against cancer. Biomed Pharmacother. 2018. https://doi.org/10.1016/j.biopha.2018.09.06 .

Huang J, Qian W, Wang L, Wu H, Zhou H, Wang AY, et al. Functionalized milk-protein-coated magnetic nanoparticles for MRI-monitored targeted therapy of pancreatic cancer. Int J Nanomedicine. 2016;7(11):3087–99.

Aisida SO, Ugwu K, Akpa PA, Nwanya AC, Nwankwo U, Bashir AKH, et al. Synthesis and characterization of iron oxide nanoparticles capped with Moringa Oleifera: the mechanisms of formation effects on the optical, structural, magnetic and morphological properties. Mat Today Proc. 2019. https://doi.org/10.1016/j.matpr.2020.03.167 .

Ali I, Peng C, Naz I, Khan ZM, Sultan M, Islam T, et al. Phytogenic magnetic nanoparticles for wastewater treatment: a review. RSC Adv. 2017;7(64):40158–78.

Stephen Inbaraj B, Chen BH. Nanomaterial–based sensors for detection of foodborne bacterial pathogens and toxins as well as pork adulteration in meat products. J Food Drug Anal. 2016. https://doi.org/10.1016/j.jfda.2015.05.001 .

Rochelle M. Cornell US. The Iron Oxides: Structure, Properties, Reactions, Occurrences and uses, 2nd, completely revised and extended edition. 2006;703: https://www.wiley.com/en-us/The+Iron+Oxides%3A+Structure%2C+Properties%2C+Reactions%2C+Occurrences+and+Uses%2C+2nd%2C+Completely+Revised+and+Extended+Edition-p-9783527606443%0A . https://www.wiley.com/en-in/The+Iron+Oxides:+Structure,+Properties,+Reactions

Ahmad S, Riaz U, Kaushik A, Alam J. Soft template synthesis of super paramagnetic Fe 3O 4 nanoparticles a novel technique. J Inorg Organomet Polym Mater. 2009;19(3):355–60.

Al-Asmari AK, Albalawi SM, Athar MT, Khan AQ, Al-Shahrani H, Islam M. Moringa oleifera as an Anti-Cancer Agent against breast and colorectal cancer cell lines. PLoS ONE. 2015;10(8):e0135814.

Article   PubMed   PubMed Central   CAS   Google Scholar  

Isaac RSR, Sakthivel G, Murthy C. Green synthesis of gold and silver nanoparticles using averrhoa bilimbi fruit extract. J Nanotechnol. 2013. https://doi.org/10.1155/2013/906592 .

Savi M, Rossi S, Bocchi L, Gennaccaro L, Cacciani F, Perotti A, et al. Titanium dioxide nanoparticles promote arrhythmias via a direct interaction with rat cardiac tissue. Part Fibre Toxicol. 2014. https://doi.org/10.1186/s12989-014-0063-3 .

Huang CC, Tsai CY, Sheu HS, Chuang KY, Su CH, Jeng US, et al. Enhancing transversal relaxation for magnetite nanoparticles in mr imaging using Gd3+-chelated mesoporous silica shells. ACS Nano. 2011;5(5):3905–16.

Ebadi M, Saifullah B, Buskaran K, Hussein MZ, Fakurazi S. Synthesis and properties of magnetic nanotheranostics coated with polyethylene glycol/5-fluorouracil/layered double hydroxide. Int J Nanomedicine. 2019;14:6661–78.

Attari E, Nosrati H, Danafar H, Kheiri MH. Methotrexate anticancer drug delivery to breast cancer cell lines by iron oxide magnetic based nanocarrier. J Biomed Mater Res A. 2019;107(11):2492–500.

Javanbakht T, Laurent S, Stanicki D, Wilkinson KJ. Relating the surface properties of superparamagnetic iron oxide nanoparticles (SPIONS) to their bactericidal effect towards a biofilm of streptococcus mutans. PLoS ONE. 2016. https://doi.org/10.1371/journal.pone.0154445 .

Yildiz I, Shukla S, Steinmetz NF. Applications of viral nanoparticles in medicine. Curr Opin Biotechnol. 2011. https://doi.org/10.1016/j.copbio.2011.04.020 .

Download references

Acknowledgements

We are grateful to the Makerere’s Mechanical Engineering department, RTC lab in the Makerere’s College of Veterinary, Animal Resources and Biosecurity, Materials Research Department (MRD), iThemba LABs, Cape Town in South Africa for granting access to the SEM-EDX, UV–Vis spectrophotometer and the XRD instruments, respectively.

We are grateful to the African Centre of Excellence in Materials, Product Development and Nanotechnology (MAPRONANO ACE) under Makerere University for funding this work.

Author information

Authors and affiliations.

Department of Medical Physiology, Makerere University, Kampala, Uganda

Henry Fenekansi Kiwumulo, Haruna Muwonge & Robert Tamale Ssekitoleko

Department of Human Anatomy, Makerere University, Kampala, Uganda

Charles Ibingira

Department of Mechanical Engineering, Makerere University, Kampala, Uganda

Michael Lubwama & John Baptist Kirabira

Habib Medical School, Islamic University in Uganda (IUIU), Kampala, Uganda

Haruna Muwonge

You can also search for this author in PubMed   Google Scholar

Contributions

HFK performed the repeated rounds of synthesis and characterization testing, RTS and JBK designed, tailored and supervised the study, HM, ML and CI analyzed the data. All authors contributed to the draft and revised the manuscript for intellectual content. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Robert Tamale Ssekitoleko .

Ethics declarations

Ethics approval and consent to participate.

Not applicable.

Consent for publication

Competing interests.

The authors declare no competing interests of any sort.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ . The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Cite this article.

Kiwumulo, H.F., Muwonge, H., Ibingira, C. et al. Green synthesis and characterization of iron-oxide nanoparticles using Moringa oleifera: a potential protocol for use in low and middle income countries. BMC Res Notes 15 , 149 (2022). https://doi.org/10.1186/s13104-022-06039-7

Download citation

Received : 15 February 2022

Accepted : 13 April 2022

Published : 25 April 2022

DOI : https://doi.org/10.1186/s13104-022-06039-7

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Green synthesis
• Bio-compatible
• Iron oxide nanoparticles
• Scanning Electron Microscope
• Energy Dispersive X-ray

BMC Research Notes

ISSN: 1756-0500

• General enquiries: [email protected]

• My Shodhganga
• Receive email updates
• Edit Profile

Shodhganga : a reservoir of Indian theses @ INFLIBNET

• Shodhganga@INFLIBNET
• Karpagam University
• Biotechnology

Items in Shodhganga are licensed under Creative Commons Licence Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0).

Maintenance work is planned from 21:00 BST on Tuesday 20th August 2024 to 21:00 BST on Wednesday 21st August 2024, and on Thursday 29th August 2024 from 11:00 to 12:00 BST.

During this time the performance of our website may be affected - searches may run slowly, some pages may be temporarily unavailable, and you may be unable to log in or to access content. If this happens, please try refreshing your web browser or try waiting two to three minutes before trying again.

We apologise for any inconvenience this might cause and thank you for your patience.

RSC Advances

Chemically synthesized nanoparticles of iron and iron-carbides.

* Corresponding authors

a Department of Applied Physics and Astronomy, University of Sharjah, Sharjah, UAE E-mail: [email protected]

b Research Institute for Medical and Health Sciences (RIMHS), University of Sharjah, Sharjah, UAE

c Dartmouth Hitchcock Medical Center, Department of Radiology, Lebanon, NH, USA

d National Center for Scientific Research, Demokritos, Greece

e Department of Medical Diagnostic Imaging, University of Sharjah, Sharjah, UAE

f Department of Physics and Astronomy, University of Delaware, Delaware, USA

In this paper, we report a one-pot chemical synthesis technique for the preparation of iron and iron-carbide nanoparticles. Mössbauer spectroscopy, X-ray diffraction and magnetometry were used as the main tools to identify the different phases of Fe–C present. The influence of experimental parameters on the structural and compositional properties of nanoparticles was investigated in detail. These particles show ferromagnetic behavior with room temperature coercivity higher than 300 Oe. The X-ray diffraction was complemented by Mössbauer spectroscopy and thermo-magnetic analysis. Remarkably, the carbon content in iron-carbide nanoparticles (carbon rich or carbon poor iron-carbides) can be modulated simply by varying the experimental conditions, like the reaction time, temperature and iron precursor concentration. Magnetic properties can be tailored based upon crystallographic structure and particles composition.

Article information

Download Citation

Permissions.

H. Khurshid, Y. A. Abdu, E. Devlin, B. A. Issa and G. C. Hadjipanayis, RSC Adv. , 2020,  10 , 28958 DOI: 10.1039/D0RA02996C

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence . You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content .

Social activity

Search articles by author, advertisements.

Academia.edu no longer supports Internet Explorer.

To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to  upgrade your browser .

Enter the email address you signed up with and we'll email you a reset link.

• We're Hiring!
• Help Center

PhD Thesis IRON OXIDE NANOPARTICLES AND THEIR TOXICOLOGICAL EFFECTS: IN VIVO AND IN VITRO STUDIES

Related Papers

Journal of Applied Toxicology

Gábor Nyírő

Pan African Journal of Life Sciences

Oluyemi Akinloye

Background: Decreased particle size and increased surface area to volume ratio are beneficial properties of nanoparticles. However, there are contrasting reports on their potential organotoxic effects. The dose de-pendent toxicity effects of iron III oxide nanoparticles (Fe2O3NPs) on the biochemical indices and histology of select-ed organs of adult male mice were investigated. Methods: Fifty six male mice weighing between 25-32g were randomly assigned into 4 groups (n=14), the control/group 1 was given the vehicle/distilled water, while animals in groups (2-4) received 5 mg/kg, 25 mg/kg and 50mg/kg body weights of Fe2O3NPs (INP) respectively by intraperitoneal route of administration for 14 days after which blood samples were drawn for biochemical analysis. Histopathology studies on the effect of graded doses of INP on the architecture of the liver, kidney and testes of mice were carried out. Results: There were significant increases in plasma sodium, creatinine, urea, chloride, al...

BioMed Research International

Cristina Popa

International Journal of Molecular Sciences

Otilia Cinteza

Particle and fibre toxicology

Gaurav Sharma

Nanomedicine Research Journal (NMRJ)

Experimental and Therapeutic Medicine

maher Kamel

Chemical Research in Toxicology

Krzysztof Janeczko

BioMed research international

Elena Sizova

The research was performed on male Wistar rats based on assumptions that new microelement preparations containing metal nanoparticles and their agglomerates had potential. Morphological and functional changes in tissues in the injection site and dynamics of chemical element metabolism (25 indicators) in body were assessed after repeated intramuscular injections (total, 7) with preparation containing agglomerate of iron nanoparticles. As a result, iron depot was formed in myosymplasts of injection sites. The quantity of muscle fibers having positive Perls&#39; stain increased with increasing number of injections. However, the concentration of the most chemical elements and iron significantly decreased in the whole skeletal muscle system (injection sites are not included). Consequently, it increased up to the control level after the sixth and the seventh injections. Among the studied organs (liver, kidneys, and spleen), Caspase-3 expression was revealed only in spleen. The expression ...

American Journal of Respiratory Cell and Molecular Biology

Hillel Koren

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.

RELATED PAPERS

International Journal of Nanomedicine

ramovatar meena

Nanotoxicology

Jana Tulinska

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Nanomaterials (Basel, Switzerland)

Todd Stueckle

Sourabh Dwivedi

Maria Dusinska

Ghada Hasabo

Anatomical Sciences Journal

Biosciences, Biotechnology Research Asia

Experimental and Toxicologic Pathology

Leila Sadeghi

Journal of toxicologic pathology

General physiology and biophysics

Daniela Predoi

Medico-Legal Update

amel altaee

Boris Nikolaev

Journal of Nanomaterials

Simona Iconaru

Nanotechnology

Francisco Terán

Iraqi journal of Veterinary Sciences

Dr.Majida Al-Qayim

Niluka Dissanayake

Iranian Red Crescent Medical Journal

Hossein N varzi

Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease

Tim G St Pierre , David Macey

Michel Seve

Archives of Biological Sciences

Ivana Cacciatore

REVIEWS ON ADVANCED MATERIALS SCIENCE

Dubravka Nikolovski

•   We're Hiring!
•   Help Center
• Find new research papers in:
• Health Sciences
• Earth Sciences
• Cognitive Science
• Mathematics
• Computer Science
• Academia ©2024