A Photo‐induced Cross‐Linking Enhanced A and B Combined Multi‐Functional Spray Hydrogel Instantly Protects and Promotes of Irregular Dynamic Wound Healing

Abstract Wounds in harsh environments can face long‐term inflammation and persistent infection, which can slow healing. Wound spray is a product that can be rapidly applied to large and irregularly dynamic wounds, and can quickly form a protective film in situ to inhibit external environmental infection. In this study, a biodegradable A and B combined multi‐functional spray hydrogel is developed with methacrylate‐modified chitosan (CSMA 1st ) and ferulic acid (FA) as type A raw materials and oxidized Bletilla striata polysaccharide (OBSP) as type B raw materials. The precursor CSMA 1st ‐FA/OBSP (CSOB‐FA 1st ) hydrogel is formed by the self‐cross‐linking of dynamic Schiff base bonds, the CSMA‐FA/OBSP (CSOB‐FA) hydrogel is formed quickly after UV–vis light, so that the hydrogel fits with the wound. Rapid spraying and curing provide sufficient flexibility and rapidity for wounds and the hydrogel has good injectability, adhesive, and mechanical strength. In rats and miniature pigs, the A and B combined spray hydrogel can shrink wounds and promote healing of infected wounds, and promote the enrichment of fibrocyte populations. Therefore, the multifunctional spray hydrogel combined with A and B can protect irregular dynamic wounds, prevent wound infection and secondary injury, and be used for safe and effective wound treatment, which has a good prospect for development.