Preparation of stable aqueous solution of keratins, and physiochemical and biodegradational properties of films

Abstract

A stable aqueous solution of reduced keratins was prepared by extracting the proteins from wool (Corriedale) with a mixture of urea, mercaptanol, surfactant, and water at 40-60°C. Sodium dodecyl sulfate was especially effective as a surfactant, not only in promoting extraction but also in stabilizing the aqueous protein solution. The proteins had the following constants: MW, 52,000-69,000 daltons; cysteine content, 8-9 mol %; pl about 6.7. A clear film was readily prepared from a keratin solution containing glycerol. The film was insoluble in water and organic solvents including dimethyl sulfoxide. The keratin film was permeable to glucose, urea, and sodium chloride. The keratin film was degraded in vitro (by trypsin) and in vivo (by subcutaneous embedding in mice).