Abstract

Iron oxide nanoparticles (IONPs) have grabbed much attention in the past years as they have different polymeric forms, including
α-Fe2O3 (hematite), γ- Fe2O3(maghemite), Fe3O4(magnetite), β-Fe2O3, and ε-Fe2O3. This review focuses on the various methods
of synthesis of IONPs and their application. IONPs can be synthesized by variety of methods such as sol–gel, microemulsion,
sonochemical, laser-assisted, microwave-assisted, and biosynthesis, of which green synthesis of nanoparticles is being promoted
and paid attention to due to its eco-friendly, non-toxic, inexpensive, and less waste producing approach. The wide variety of
applications of IONPs are attributed to its features such as magnetic properties, optimum particle size, high surface to volume
ratio, biocompatibility, stability, and easy conjugation with other molecules. Some challenges in their synthesis and future
perspective have also been discussed.