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.