Chain entanglement enhanced strong and tough wool keratin/albumin fibers for bioabsorbable and immunocompatible surgical sutures

High-performance fibers derived from non-silk proteins have garnered significant interest in biomedical applications because of their high accessibility and biocompatibility. Nonetheless, considerable challenges persist in addressing their structural defects to fabricate fibers with an optimal balance of strength and toughness. Herein, an entanglement-reinforced strategy is proposed to reconstruct high-performance non-silk protein fibers. Regenerated keratin and bovine serum albumin (BSA) are unfolded by denaturant and complementarily composited, leveraging their intrinsic cysteine re-oxidation to generate a robust mechanical cross-linking network without the requirement of an external crosslinker. The resulting drawn keratin/BSA composite fiber (DKBF) exhibits balanced mechanical performances with a breaking strength of approximately 250 MPa and a toughness of around 70 MJ m-3, outperforming that of reported regenerated keratin fibers and comparable to many natural or artificial silk fibers. Additionally, DKBFs demonstrate redox-responsive mechanical behavior and hydration-induced reversible shape memory. The DKBFs show good suturing capability for wound repair in female animal models due to their excellent bioabsorbability and immunocompatibility. This work offers valuable insights into addressing the current challenges in manufacturing mechanically robust and tough non-silk protein fibers, bringing hope for the development of more sustainable and versatile materials. Fibers derived from non-silk proteins hold potential for various biomedical applications, but mechanically-balanced and highly-biocompatible regenerated protein fibers are elusive. Here, the authors report an entanglement-reinforced strategy to fabricate keratin/albumin bio-fibers that show high strength and toughness, along with favorable biocompatibility, degradability and immunocompatibility.