Mussel catechol-inspired tough hydrogels with self-healing, wet adhesion and controllable drug release for wound dressing applications

Inspired by the catechol chemistry of mussel adhesive proteins, we designed a multifunctional hydrogel that combines antibacterial activity, self-healing, excellent biocompatibility, enhanced mechanical properties, adjustable adhesion, and controlled drug release. A P(AA-co-UH) primary network was synthesized through the copolymerization of acrylic acid and urushiol, while a P(CNC-PB) secondary network was assembled from cellulose nanocrystals, polyvinyl alcohol, and borax. The two networks were interlaced to form an interpenetrating polymer network, which substantially enhanced mechanical performance, achieving a tensile strength of 61.45 kPa and excellent fatigue resistance. The cis -hydroxy groups in cellulose nanocrystal and polyvinyl alcohol, along with the hydroxyl groups of urushiol, engage in dynamic covalent borate ester bonds with borate ions in borax solution. This dynamic covalent crosslinking provides a way to control the concentration of catechol groups, thereby tuning the adhesive performance. Moreover, the incorporation of borax modifies the pore structure and swelling behavior of hydrogels, enabling controlled drug release. This hydrogel exhibits excellent self-healing properties, wet adhesion, and drug-loading capacity. It can self-heal within 5 h, with wet adhesion increasing from 14.13 kPa to 17.51 kPa and drug loading capacity rising from 10.9 mg/g to 19.6 mg/g. Antibacterial and cytotoxicity assays confirmed its favorable biocompatibility and antimicrobial efficacy. In summary, these multifunctional hydrogels are highly promising for smart medical dressing applications.