Functionalization of Fe3O4 nanoparticles

Magnetic iron oxide (Fe3O4) nanoparticles are used as ferrofluids and in biomedical field as diagnostic and therapeutic tools, contrast agents in magnetic resonance imaging, drug delivery to tumor cells, cancer treatment by hyperthermia. These applications usually require uniform, chemically stable and monodispersed particles in liquid media. As a result of anisotropic dipolar attraction, nanoparticles of iron oxide aggregate into large clusters which may lead to the failure of their properties. Surface modification is often required to prevent such aggregation of nanoparticles. It has been already proved that aggregation can be avoided by surface modification of Fe3O4 nanoparticles using silica. The present work seeks the preparation and characterizations of monodispersed magnetic nanoparticles (Fe3O4) as well as silica coating. Fe3O4 nanoparticles have been synthesized using thermal decomposition route. The reaction involves high temperature (230 degrees C) heating of iron acetylacetonate Fe(acac)(3) in the presence of reducing agent and surfactant. Structural characterizations and surface chemistry of nanoparticles have been analyzed using X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. Further work has been extended by coating as prepared Fe3O4 nanoparticles with silica. It reveals from microscopic analysis that each silica sphere contains several monodisperse Fe3O4 NP.