Bioderived Green Algae Metabolite as a Latent Cross-Linking Agent for Protein-Based Hydrogels with High Potential for Skin Repair Applications

Despite advances in wound treatment through tissue engineering, the rapid colonization of biomaterials by host cells remains a crucial step toward complete wound healing. Thanks to their excellent biocompatibility, biodegradability, low antigenicity and cost-effectiveness, cross-linked hydrogels have attracted much attention as a viable solution for wound treatment. In this work, we have developed an inovative cross-linking method for gelatin-based hydrogels inspired by the wound closure mechanism of the green algae Caulerpa taxifolia . Caulerpenyne (CYN), a metabolite extracted from the algae, was used as a latent cross-linking agent for gelatin. The covalent cross-linking process is triggered by an in situ and on-demand deacetylation of the enol acetate functionalities of CYN in oxytoxin 2 (OXY) containing 1,4-dialdehyde, which immediately reacts with the lysine residue in gelatin. The content of ε-amino groups in gelatin was monitored as a function of CYN concentration. Swelling and gel content were analyzed as a function of CYN concentration. Morphology, rheological and biological properties were evaluated by in vitro and in vivo tests. Cell adhesion and viability tests performed with OXY-cross-linked hydrogels and compared with non-cross-linked and genipin-cross-linked gelatin showed excellent performance. Their use in whole skin wounds in pigs showed that CYN-cross-linked hydrogels promoted complete skin regeneration without any cytotoxicity, making them extremely promising matrices in the field of regenerative medicine.