Photo-induced adhesive carboxymethyl chitosan-based hydrogels with antibacterial and antioxidant properties for accelerating wound healing

Designing adhesive hydrogel wound dressings with inherent antibacterial and antioxidant properties is desirable to treat cutaneous full-thickness injuries in clinical care. Herein, a series of photo-induced Schiff base crosslinking-based adhesive hydrogels with promising traits are designed and prepared through Diels-Alder (DA) reactions between functional groups-grafted carboxymethyl chitosan (CMCS) and a photo-responsive polyethylene glycol (PEG) crosslinker. The quaternary ammonium and phenol groups in modified CMCS endows hydrogels excellent antibacterial and antioxidant properties. Upon UV (365 nm) irradiation, the generated onitrosobenzaldehyde from the photo-isomerization of o-nitrobenzyl in PEG derivative can subsequently crosslink with amino groups on tissue interfaces via Schiff base, endowing the hydrogel with well adhesiveness. Additionally, the hydrogel exhibits good BSA adsorption capacity, cytocompatibility and hemostatic property. The in vivo full-thickness skin defect study on mice indicates that the multi-functional hydrogel with considerable collagen deposition and vascularization capacities can be an effective and promising adhesive dressing for improving wound healing.