Novel in situ and rapid self-gelation recombinant collagen-like protein hydrogel for wound regeneration: mediated by metal coordination crosslinking and reinforced by electro-oxidized tea polyphenols.

Recombinant collagen holds immense potential in the development of medical functional materials, yet its widespread application remains hindered by the absence of a suitable self-assembly strategy. In this article, we report the discovery that the bacterial-derived collagen-like protein Scl2 can rapidly self-gelation (~1 minute at pH ~7) due to properties enabled by metal coordination crosslinking. This was achieved by fusing metal ion chelating peptides to both termini of the protein. Our research further reveals the critical role of electrostatic interaction between globular domains (V domains) of recombinant collagen in the self-assembly process. We show that modifying the negative charge load of the N-terminal α-helix of the V domain enables control over the self-assembly time (from 1 min to 30 min) and strength (from 8 kPa to 26 kPa) of the Scl2 hydrogel. By adjusting the molecular weight of the core collagen-like (CL) domain, we have remarkably further enhanced the strength of the Scl2 hydrogel to 78 kPa. Moreover, we innovatively employed electro-oxidized tea polyphenols (EOTP) to enhance the stability of the Scl2 hydrogel, resulting in the formation of a reliable self-assembled metal coordination hydrogel at physiological temperature. This approach not only eliminates the need for toxic chemical crosslinking agents but also confers the material with multiple functionalities, such as adhesion, antibacterial, and antioxidant properties. The novel recombinant Scl2 hydrogel exhibited exceptional in situ self-gelation and injectable properties. This innovative hydrogel not only demonstrates remarkable biological activity but also exhibits remarkable tissue repair-promoting capabilities in full-thickness skin injury models (shorten healing cycle by more than 30%). The convenient and versatile nature of this recombinant collagen hydrogel makes it promising for clinical applications in injury treatment, demonstrating broad applications in the future.