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Collagen-based bio-hydrogels are undoubtedly a hot spot in the development of biological dressings for wound healing promotion. Herein, glutamine transaminase (TGase), a biological nontoxic cross-linker with high specific activity and reaction rate under mild conditions, was utilized for the self-catalytic cross-linking of the regenerated collagen (COL) fibril hydrogel fabricated through a molecular self-assembly method. The results showed that the natural triple helical conformation of COL remained completely integrated after self-catalytic cross-linking TGase, which was definitively the fundamental for maintaining its superior bioactivity. It was worth noting that TGase could promote the self-assembly process of COL building blocks into a higher order D-period cross-striated structure. Also, the reconstructed TGase cross-linked COL fibrils exhibited a higher degree of interfiber entanglements with more straight and longer fibrils. Meanwhile, the thermal stability of COL was significantly improved after introducing TGase. Besides, the cytocompatibility analysis suggested that the regenerated COL fibril hydrogel showed excellent cell growth activity and proliferation ability when the dosage of TGase is less than 40 U/g. Further, animal experiments indicated that the targeted COL fibril hydrogel could significantly promote skin wound healing, exhibiting better capacity of skin tissue for regeneration than the COL hydrogel untreated as expected. Therefore, the reconstructed TGase cross-linked COL fibril hydrogel could serve as a novel soft material for wound healing promotion.

Gelatin (GE), a nontoxic and degradable biomass resource, is a multistage hydrolysate of collagen. However, its application in adhesives was always limited by its brittleness and poor water resistance. In order to overcome this shortcoming, herein, epoxy-terminated hyperbranched polymers (EHPAEs) were first selected as a cross-linking agent to modify the GE extracted from leather solid wastes to prepare a series of novel GE-based environmentally friendly adhesives. First, EHPAE was synthesized and the structure of the hyperbranched polymer was measured by Fourier-transform infrared and 1H NMR spectroscopy. Then, the adhesives were obtained using the EHPAE to modify GE. The adhesion effect of the prepared adhesives was evaluated by tensile and T-peel tests on the surface of leather, in order to determine whether this adhesive achieved the quality requirements for footwear and bags. The result indicated that EHPAE-modified GE-based adhesives had higher solid content, superior adhesion ability, and water resistance. Moreover, the bonding layer of this adhesive was tough and ductile, while the bonding layers of the recently reported GE-based adhesives were brittle. This adhesive also surpassed the recently reported GE-based adhesives in terms of water resistance and adhesion performance.

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