Journal de bioanalyse et de biomédecine

Magnetic Properties of Iron Oxides in the Human Globus pallidus

Abstract

Martin Kopáni, Jana Hlinková, Hermann Ehrlich, Dušan Valigura and Roman Boča

Several types of iron oxides can be found in the various parts of the human brain. These can be highlighted in the light microscopy and using scanning or transmission mode of the electron microscopy. Some of them are non-magnetic, some, on the contrary, display magnetic response. It is not clear which kind of magnetic particles are accumulated in the human brain as inorganic deposits. Light microscopy, electron microscopy and sensitive Superconducting Quantum Interference Device (SQUID magnetometer) were used in order to detect iron deposits and their magnetic response in the samples extracted from the Globus pallidus of the human brain. Electron microscopy reveals a presence of the single crystals of hematite (α-Fe2O3) of the size up to 1000 nm in the samples extracted from G. pallidus because of the diffractograms characteristic for the hexagonal unit cell; this mineral offers basically a diamagnetic response. The temperature dependence of the magnetic susceptibility allows a classification of the samples into three groups: mostly diamagnetic I, prevailing paramagnetic III, and an intermediate class II. The bulk samples exhibit a long-range magnetic ordering with magnetic hysteresis evidenced not only at low temperature but also at the room temperature. The recorded magnetic functions refer either to the presence of magnetite (Fe3O4), or maghemite (γ-Fe2O3). Iron oxides and oxidohydroxides found as inorganic deposits in the human brain can result from interaction between iron and microenvironment in the form of polysaccharides of glycoconjugates. They display magnetoactivity characteristic for magnetite and/or maghemite.