Semiconductor Physics, Quantum Electronics & Optoelectronics, 21 (1), P. 95-99 (2018).
DOI: https://doi.org/10.15407/spqeo21.01.095
Nonmonotonic (in concentration) conductivity of aqueous solutions of fungal melanin
O.V. Kovalchuk1,2, T.M. Kovalchuk3
2Kyiv National University of Technologies and Design, 2, Nemirovich-Danchenko str., 01011 Kyiv, Ukraine
E-mail: akoval@knutd.com.ua
3V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, prospect Nauky, 03680 Kyiv, Ukraine
Abstract. The conductivity of aqueous (distilled and natural water) solutions of fungal melanin (purified and non-purified) has been studied. It has been shown that, in the presence of impurities, the conductivity of solution increases (for the concentration 0.1 wt% about an order of magnitude). On the concentration dependences of the melanin conductivity within the range of 0.0001 to 1 wt.% at least three particular sections have been detected. It was suggested that the presence of such sections is caused by three types of aggregation of melanin molecules: aggregation of several (mostly oppositely charged) molecules under the lowest melanin concentration, formation of nanoscale melanin clusters for the concentration of 0.002 to 0.06 wt.% and formation of micelles, when the melanin concentration is higher than 0.1 wt.%.
Keywords: melanin, conductivity, concentration, aqueous solutions.
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