Liquid‐Triggered Self‐Gelling Powder as Gradient Anti‐Swelling Sealant for Achieving Simultaneous Hemostasis and Anti‐Postoperative Adhesion

Hydrogel-based wet-adhesion sealants are critical for wound sealing and repair, yet traditional hydrogel patches struggle to conform to irregular wounds while in situ self-curing systems commonly cause unintended tissue adhesion. To address these challenges, a gradient hydration concept for preparing the novel Chitosan-based mixed self-gelling (CMS) powder with simultaneous hydration lubrication and wet adhesion functions is first proposed. The CMS powder can form a dual-network hydrogel after liquid-triggered using synergistic interactions between bottle-brushed positive/negatively charged macromolecules (non-covalent effect) and aldehyde-functionalized polysaccharides (dynamic covalent crosslinking). The resulting hydrogel exhibits excellent biomechanical stability and reliable long-term tissue adhesion features after achieving completely swelling equilibrium in the physiological environment. Upon being applied to the wound cavity, the CMS powder demonstrates rapid gelation and robust tissue adhesion to realize complete coverage of irregular wounds, and exhibits excellent hemostatic properties in a rat liver injury model. Importantly, the top layer of the hydrogel generates a highly hydrated lubrication layer while its bottom side contacted with tissue still retains the good adhesive function, endowing the CMS powder with postoperative anti-adhesion effects in a rat intestinal adhesion model. This self-gelling powder demonstrates its unique application advantages as the first anti-adhesion tissue sealants in biomedical engineering.