Gelation mechanism of regenerated silk fibroin aqueous solution during storage

Abstract

This study investigated the gelation mechanism of regenerated silk fibroin (RSF) aqueous solution during storage. Gel permeation chromatography analysis of the RSF solution after various times in storage revealed decreasing molecular size by molecular cleavage according to the storage time. Rapidly decreasing molecular size was observed near the gelation time. However, no gelation was observed in the case of an RSF aqueous solution containing only lower molecular weight molecules. Particle analysis of an RSF aqueous solution during storage showed formation of around 100–400 nm diameter particles by storage. The RSF aqueous solution viscosity decreased according to the storage time. The secondary structure of RSF freeze-dried the aqueous solution at various storage times was measured using FTIR analysis, which indicated an increasing β-sheet structure ratio as the storage time progressed. Taken together, we proposed the gelation mechanism of RSF aqueous solution during storage and discussed the proposed mechanism.