Laccase-mediated construction of flexible double-network hydrogels based on silk fibroin and tyramine-modified hyaluronic acid.

Silk fibroin (SF) is a promising biomaterial with attractive properties, however, the practical applications of pure regenerated SF materials were severely restricted by their poor water retention and low elasticity. In this study, a tyramine-modified hyaluronic acid (mHA) was introduced to SF chains, followed by constructing double-network hydrogels via laccase-mediated crosslinking of SF and mHA. Mechanism of the enzymatic coupling reaction between SF and mHA was investigated using the model compounds. The morphology, mechanical property, and swelling behavior of SF-g-mHA hydrogel were evaluated. The results reveal that combination use of SF and mHA endowed the obtained hydrogels with high structural stability, improved mechanical properties and drug release behavior, which overcame the intrinsically poor formability of the pure fibroin hydrogels. This work provides a novel method to construct a double-network hydrogel with high flexibility and toughness, and expands the application range of the SF-based materials in biomedical fields.