Magnetic nanoparticles have potential applications in bio-sensors, bio-separations and biomedicine. Highly monodisperse magnetic nanoparticles like FePt have been synthesized through organometallic routes that use surfactants like oleic acid and oleyl amine to stabilize particles in non-polar solvents like hexane. However, for biological applications the surface of these nanoparticles needs to be modified to make them biocompatible and to impart specific functionality. A promising technique to accomplish this task is to make biocompatible oxide shells around the hydrophobic solvents that not only make them hydrophilic but also make them amenable to introducing desirable functionalities.

In the present work, we report on the synthesis of FePt nanoparticles with iron oxide, silica and magnesium oxide shells around them. We also report on the surface modification of these nanoparticles to introduce specific functionality on their surface. After functionlizing the conjugation of these nanoparticles to biological entities like proteins and viruses was studied.