Synthesis and Stability of Highly Crystalline and Stable Iron/Iron Oxide Core/Shell Nanoparticles for Biomedical Applications

Biocompatible iron nanoparticles exhibiting a high magnetic moment are potentially useful for a variety of biomedical applications. However, once exposed to air, iron nanoparticles partially oxidize, effectively reducing their magnetic performance. Here, near-monodisperse iron nanocrystals were synthesized and oxidized on the surface to form iron/iron oxide core/shell nanoparticles. The presence of excess stabilizers was shown to stabilize the core/shell nanoparticles, thus preventing further oxidation. The advantage of these core/shell nanoparticles in biomedicine, is shown by greater cellular MRI contrast enhancement compared to pure iron oxides without increase in cytotoxicity.