Effect of Extraction Method on the Structure and Performance of Keratin Hydrogel

Keratin-based hydrogels have been used more and more in the fields of biomedical materials and cosmetics. However, there are obvious differences in the molecular weight and its distribution as well as the content of active sulfhydryl groups of keratin raw materials extracted by different technologies. In this paper, four kinds of keratin-based hydrogels were prepared from wool keratin extracted by sodium sulfide method, L-cysteine method, sodium bisulfite method and peracetic acid method, respectively, and named KH1, KH2, KH3 and KH4 in sequence. The pore structure, compressive mechanical properties, swelling properties, rheological behavior, viscosity, pH and H₂O₂ responsiveness of keratin-based hydrogels were studied according to the structure and properties of keratin obtained by different extraction processes. The experimental results show that the pore sizes of KH1 and KH2 range from 30 μm to 90 μm, while those of KH3 and KH4 range from 100 μm to 200 μm. KH1 and KH2 show high energy storage moduli and good resistance to compression, while KH4 has the lowest energy storage modulus and is easily compressed. In addition, all four keratin hydrogels showed good pH and H₂O₂ responsiveness. This study has certain guiding significance for how to select keratin raw materials to prepare keratin-based biomaterials.