Surface protected and modified iron based core-shell nanoparticles for biological applications

Excellent quality superparamagnetic iron oxide coated iron nanoparticles were prepared via one pot synthesis with narrow size distribution. These particles were subsequently coated with FexOy, FePt or Pt shell to give long term protection to the highly reactive zero-valent iron core. Clear core-shell morphology was observed in the TEM images of FexOy and FePt coated particles and the magnetic properties suggested that these shells provided good protection to the core from oxidation, in particular iron oxide coated particles retained their magnetism for well over a year. FePt coated particles show superior magnetic properties to FePt particles alone and were found to be promising in biological applications. The magnetic studies further revealed that the saturation moments of the resultant particles were dependent on the type of shell used for encapsulation. Surface modifications of these particles were done with suitable hydrophilic ligands and they showed excellent stability and solubility in water and different buffer solutions which reveals the suitability of these nanoparticles for biomedical research.