Efficient Extraction of Wool Keratin Governed by Simultaneous Cation and Anion Effects: From Secondary Structure Studies to High α-Helix Keratin Content

Wool has excellent elastic resiliency and shape-memory characteristics, which are determined by the α-helix keratin of wool, but it is difficult to extract a high content of α-helix structure keratin from wool, owing to its poor thermodynamic stability. In this work, two kinds of metal salts together with different reducing agents are employed in eight different solvents to dissolute wool and extract keratin with a high content of α-keratin. The extracted keratin shows the maximum values of 77.33% dissolution rate, 65.01% extraction rate, and 27.58% α-helix keratin. Meantime, the effects of different dissolution systems on the α-helix structure are systematically studied by XRD, FTIR, and EDS analysis; based on the structure and properties of the regenerated keratin, the extraction mechanism for high-content α-keratin is proposed, which endows α-helix keratin-based materials with possibilities to develop high-elasticity and shape-memory materials in bioengineering and bioelectronic applications.