Effect of sericin concentration and ethanol content on gelation behavior, rheological properties, and sponge characteristics of silk sericin

Sericin gels and sponges have attracted attention in the biomedical and cosmetic fields because sericin has useful properties including a high UV and oxidation resistance, inhibition of UVB-induced apoptosis in human skin keratinocyte, wound healing, and wrinkle resistance effects. In this study, the effects of sericin concentration and ethanol content on the gelation behavior, rheological properties, and sponge characteristics of sericin were examined. As the sericin concentration increased, the rate of gelation of sericin accelerated and gel strength increased significantly. This occurred up to an ethanol content of 15%. Above that, the rate of gelation and the gel strength decreased. There was no change in the gel-sol transition temperature of sericin with the sericin concentration, although more ethanol addition resulted in a decrease in the starting temperature of thermal gel disruption. The crystallinity index of the frozen and thawed sericin sponge did not change with the sericin concentration, whereas it increased with increasing ethanol content up to 15% and decreased above 15%. As the sericin concentration was increased, the porosity and swelling ratio of the sericin sponge decreased and the mechanical properties of sericin sponge were remarkably improved.