Iron Oxide Nanoparticles

Iron oxides are abundantly found in nature since iron is one of the most abundant materials in the earth's crust and easily form various compounds with oxygen. There are approximately 16 identified iron oxides. However, the most prevalent iron oxide nanoparticles are magnetite (Fe₃O₄), maghemite (γ-Fe₂O₃), and hematite (α-Fe₂O₃). Fe₃O₄ and γ-Fe₂O₃ show superior magnetic properties in comparison to α-Fe₂O_3. These iron oxides are ferromagnetic materials and are widely used in biomedical applications such as diagnostic magnetic resonance imaging (MRI),hyperthermia treatment of solid tumors, gene therapy tissue regeneration,and drug delivery. Non-toxic nature and biocompatibility of iron oxides are also important for these biomedical applications. α-Fe₂O₃ is found to be the most stable form of iron oxides. It shows n-type semiconductor properties (Eg=2.1eV) under ambient conditions. Nanoparticles ofα-Fe₂O₃ are used as electrode material in photoelectrochemical cells, catalysts, and sensing elements in gas sensors and humidity sensors.