Visible light crosslinkable human hair keratin hydrogels

Keratins extracted from human hair have emerged as a promising biomaterial for various biomedical applications, partly due to their wide availability, low cost, minimal immune response, and the potential to engineer autologous tissue constructs. However, the fabrication of keratin‐based scaffolds typically relies on limited crosslinking mechanisms, such as via physical interactions or disulfide bond formation, which are time‐consuming and result in relatively poor mechanical strength and stability. Here, we report the preparation of photocrosslinkable keratin‐polyethylene glycol (PEG) hydrogels via the thiol‐norbornene “click” reaction, which can be formed within one minute upon irradiation of visible light. The resulting keratin‐PEG hydrogels showed highly tunable mechanical properties of up to 45 kPa in compressive modulus, and long‐term stability in buffer solutions and cell culture media. These keratin‐based hydrogels were tested as cell culture substrates in both two‐dimensional surface seeding and three‐dimensional cell encapsulation, demonstrating excellent cytocompatibility to support the attachment, spreading, and proliferation of fibroblast cells. Moreover, the photocrosslinking mechanism makes keratin‐based hydrogel suitable for various microfabrication techniques, such as micropatterning and wet spinning, to fabricate cell‐laden tissue constructs with different architectures. We believe that the unique features of this photocrosslinkable human hair keratin hydrogel promise new opportunities for their future biomedical applications.