On-demand detachable adhesive hydrogel based on dual dynamic covalent cross-linked with NIR/pH dual-responsive properties for diabetic wound healing

Favorable adhesion and on-demand detachment are the key characteristics for evaluating the effectiveness of diabetic wound dressings in clinical. Herein, a novel adhesive hydrogel is constructed based on dual dynamic covalent (Schiff base and borate ester bond) cross-linking among carboxymethyl chitosan (CMCS), 2-formylphenylboronic acid (2-FPBA) and epigallocatechin-3-gallate (EGCG) as a multifunctional dressing material for diabetic wound healing. The CMCS/2-FPBA/EGCG (CFE) adhesive hydrogels not only display good mechanical strengths (adhesive, injectable, moldable and self-healing), considerable pH-responsive EGCG releasing and photothermal properties, but also excellent antimicrobial, anti-oxidant, anti-inflammatory and angiogenetic activity. Interestingly, CFE adhesive hydrogels display on-demand detachable property while spraying natural organic acid (citric acid, salicylic acid, and vitamin C), which could avoid secondary injury during changing the wound dressings. Therefore, this study provides a promising and comprehensive strategy with great potential for application in the diabetic wound treatment.