Cellulose-based dual-crosslinked hydrogels with strong wet adhesion and benign on-demand detachment

Cellulose-based hydrogels have attracted considerable attention in biomedical engineering. However, existing cellulose-based adhesive hydrogels have several limitations, including poor wet adhesion, average antimicrobial activity and a lack of benign on-demand detachment. Using a dual-crosslinked design strategy, we created a cellulose-based hydrogel (ACCPFM) by combining polymerisable allyl cellulose, carboxymethyl chitosan and the aldehyde-cation copolymer P(FPMA-co-META). Covalent (Schiff base) and non-covalent (electrostatic interaction and hydrogen bonding) crosslinking enhance the mechanical performance of the prepared hydrogel. The introduction of P(FPMA-co-META) into the cellulose network architecture endowed the ACCPFM hydrogel with an impressive antibacterial capacity (bacterial reduction: > 95%). The ACCPFM hydrogel used the hygroscopicity of the hydroxy, carboxyl and cationic moieties to remove interfacial water on the tissue surface and then formed physical and dynamic covalent cross-links with the tissue (shear strength: > 50 kPa, tensile strength: > 70 kPa and interfacial toughness: > 110 J m(-2)). Notably, due to the dominance of physical and dynamic covalent crosslinking, which transforms timescale-dependent, on-demand detachment was achieved by applying a tailored benign solution (sodium bicarbonate/glycine) at different stages, providing a wider time window and fault-tolerance for the adhesion process. Given the ACCPFM hydrogel's strong wet adhesion, excellent antimicrobial capability and cytocompatibility, and benign on-demand detachment from tissues, cellulose-based hydrogels are expected to have potential applications in the biomedical field. {GRAPHIACAL ABSTRACT}