A bioinspired gallol-functionalized collagen as wet-tissue adhesive for biomedical applications

Bioinspired adhesives have recently gained considerable attention in biomedical applications. However, it is still a great challenge to develop a soft-tissue adhesive totally composed of natural products with desired wet adhesion strength, meanwhile which is biocompatible, biodegradable, and economically viable. To this end, we developed a novel bioadhesive (EPL/GA-COL) inspired from mussel-adhesive protein rich in both phenolic hydroxyl groups and lysine residues. In this design, a mass of gallic acid (GA), an alternative candidate for conventional L-3,4-dihydroxyphenylalanine (DOPA), was loaded onto collagen (COL) with ε-polylysine (EPL) as a “bridge”, producing EPL/GA-COLs with fruiter-like molecular structure containing pyrogallol group up to 303.8 mmol/mmol. Attractively, the EPL/GA-COLs exhibited a maximum adhesive strength of 94.7 ± 4.4 KPa towards wet porcine skin, which was superior to that of other soft-tissue biomacromolecule-based adhesives. Meanwhile, the EPL/GA-COL showed excellent biocompatibility and could be degraded completely. Furthermore, the adhesive also presented good bacteriostatic properties against both the gram-negative and gram-positive bacteria, which ensured a sterile environment for wound healing. In addition, injection of EPL/GA-COL into the full thickness skin defects of Sprague Dawley mice did not elicit structural damage as evidenced from the histological evaluation 2 weeks post-injection. And the animal assessment testified that EPL/GA-COL effectively bonded to the skin tissue under wet conditions, significantly promoting the wound-healing, meanwhile avoiding the secondary injuries and scar formation. This work proposed a facile strategy to fabricate all bio-based soft-tissue adhesives with desired properties in wet tissue adhesion, antibacterial activity, biocompatibility, biodegradability and accelerated wound-healing based on pyrogallol chemistry.