Enzyme-mediated Crosslinking of Wool. Part II: Keratin and Transglutaminase

Abstract

Keratin hydrolysates (KH) and their lyophilized powders (KP) were applied with transglutaminase (amine γ-glutamyltransferase EC 2.3.2.13; TG) to fine jersey wool fabric bleached by peroxycarboximidic acid in the first step of the ARS process. The full ARS process involving treatment with proteolytic enzyme (Esperase 8.0L™) after pretreatment by bleaching can result in up to 18% fabric strength loss in fine-gage jersey knits, yet the ARS process has met with industry acceptance. To alleviate strength loss we applied solutions of KH and KP in combination with TG as a transferase enzyme to catalyze transamidation reactions involving keratin as KH and KP and keratinaceous wool fabric in order to provide crosslinking between and among these keratin constituents. Treatments of KH from 100% to 10% owb with TG showed that shrinkage could be controlled; application of 6% owf KP and 2% owf TG controlled shrinkage to 4.89%. Scanning electron micrographs showed that the keratin material coated the fibers to fill the raised scales of the wool. The results of statistical analysis predicted the optimum application conditions of 5% KP and 5% TG. These conditions minimized felting shrinkage to 5.21% and fabric weight change to 0.26% and maximized dry burst strength to 4.7% loss and increase in fabric whiteness to 17.8 whiteness index units. Wool material, including hydrolysates and powders crosslinked by TG enzyme mediation can provide a rich resource for the production of modified keratin-based biomaterials.