Influence of Transitional Metals Doping on Conductivity of Collagen Lyophilisate and Elastin

Knowing that conductivity is a temperature function σ = f(T) allows us to estimate the thermal stability of collagen preparations from fish skin. Measurements can provide information, which is crucial for technologies applying this type of collagen. Conductivity σ measurements were performed in a constant electric field E = 1 kV/m, in the temperature range of 290-480 K. White collagen lyophilisate was used as control material. It contained neither elastin nor melanin dopants nor non-organic dopants such as gold, copper, silver or zinc. Gold, copper, silver and zinc belong to the group of transitional metals and they have intermediate properties of both alkaline metals and metals in the p block of the periodic table. The common feature of most of these elements is their ability to form coordination complexes of intense color. In the measured materials peaks were found in the temperature range of 303-323 K. Peak temperature and its shape depend on the type of material. In the case of nano-gold doping a drop in peak temperature and a decrease in conductivity were observed. The measured materials are characterized by lower thermal resistance than bovine collagen. Nevertheless, thermal stability of fish skin collagen is high enough for fish skin collagen to replace bovine collagen. The measurement results obtained for white collagen and white collagen with $Zn^{2+}$ may indicate better bonding of free water. The presence of nano-silver and nano-copper as doping agents in graphite collagen may lead to a decrease in hygroscopy of the material and, as a result, may increase its resistance to bacteria.