Effect of Au coating on the magnetic and structural properties of Fe nanoclusters for use in biomedical applications: A density-functional theory study

In this paper, we report the first systematic theoretical study of gold-coated iron nanoclusters, aiming at understanding the magnetic properties of this core-shell structure used in biomedical applications. The calculations based on density-functional theory focus on the effect of gold coating on the magnetic and structural properties of iron clusters of various sizes, and the reaction of the bare and coated iron clusters with oxygen. Our results show that the magnetic moment of iron nanocore with gold coating is still significantly higher than that in bulk Fe; the coupling between Fe atoms remained ferromagnetic and is insensitive to the thickness of the Au coating. Furthermore, oxygen remains molecular on a gold-coated Fe nanoparticle while it dissociates on a bare Fe nanoparticle. The improved chemical stability by gold coating prevents the iron core from oxidation as well as the coalescence and formation of thromboses in the body. Thus it is shown that gold coating is very promising for the magnetic particles to be functionalized for targeted drug delivery.