Properties of magnetoferritin: a novel biomagnetic nanoparticle

A soluble and biocompatible magnetic material would have many possible applications. An approach to producing biomagnetic nanophase particles with large magnetic moments is to reconstitute the iron-storage protein ferritin under conditions tailored to the synthesis of magnetite, rather than the normal ferrihydrite, in the core. The material produced in this way is called magnetoferritin. Mossbauer spectroscopy is an ideal technique for characterising such iron-containing nanophase systems. The Mossbauer spectra obtained at low temperatures and in large applied magnetic fields clearly show that the magnetoferritin core is quite different to that of ferritin. The changes in the spectra with increasing applied field indicate that the core is a ferrimagnet. Computer analysis of these spectra leads to the conclusion that the magnetoferritin core is very similar to the mineral maghemite (γ-Fe 2 O 3 ).