Abstract
Natural and synthetic melanins are able to store electrical charge and/or polarization and this effect (electret effect) depends on the water content. We performed experiments with the TSDC method (thermally stimulated depolarization currents) on bovine eye choroid and L-dopa synthetic melanin in order to determine the state of the water bound to the macromolecule. Our results can be summarized as follows: • Natural melanin in the choroid is a natural electret at physiological temperature. • TSDC on synthetic melanin is due to the presence and/or the release of water. • The calculations of the reorientation energy for water dipoles from TSDC peaks suggest the presence both of an easy water and an ice-like hard water. • On these bases we may hypothesize a model of hydration structure for melanin suitable for the interpretation of the solid-state physical properties.
Published Version
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