Study of Inorganic crystalline solids in biosystems - Magnetite in the human body

Abstract

Ferritin, the iron storage nonhaeme-protein contains a ball of hydrated iron oxides (Fe_2O_3⋅nH_2O) in its core, which is paramagnetic at room temperature. It is reported the hydrated iron oxide is the precursor of magnetite (Fe_3O_4) in the magnetotactic bacteria and polyplacophoran mollusks. It is not known whether this is the case for other organisms. In our study, we report the first detection of magnetic material in the human brain through the use of SQUID magnetometry. The material was characterized by HRTEM and EPMA. It was affirmed the material was a single crystals of magnetite. Magnetite distribution in tissues might be related with ferritin, if the core of these molecules are involved in magnetite formation in human. In general, both Perls staining and MRlmaging methods are adopted routinely for determining the relative amounts of Fe(+III) in the whole brain, which is dominated by ferritin. Both methods suggested high levels of Fe(+III) distribution in the globus pallidum, putamen, caudate, internal cerebral capsule of the cerebrum, red nucleus of the mid brain and lower concentrations in the substantia nigra of the mid brain and the dentate nucleus of the cerebellum. Whereas, our experiments showed that the distribution of magnetite is rather even in the whole human brain averaging 4 ng per gram of tissue (except for the meninges, where it is 20 times higher).