*6.4. Iron Nanoparticles (INPs)*

Iron is another imperative material used for synthesizing nanoparticles, because of unique physiochemical properties like high catalytic activity, low toxicity, high magnetism and microwave absorption ability [139–141]. The iron nanoparticles (INPs) are categorized into three groups i.e., (a) iron oxide nanoparticles (IONs), (b) iron oxide hydroxide (FeOOH) nanoparticles, and (c) zero-valent iron (ZVI) nanoparticles [142–145]. These nanoparticles are used for varied applications like bio-separation, bioprocess intensification, drug delivery, environmental remediation, ferrofluids, food preservation, gene therapy, hyperthermia, magnetic targeting, negative MRI contrast enhancement, pigments, stem cell sorting and manipulation, thermal-ablation and lithium-ion batteries [146]. Table 3 shows the plant mediated INPs with antioxidant potential. In 2015, Muthukumar and Manickam observed the high antioxidant potential of *Amaranthus spinosus* leaf extract mediated INPs, because of the presence of amaranthine and phenolic compounds in it, which act as the capping agent [104].
