Injectable Hydrogel with Rapid Coagulation, Low Swelling, and High Burst Pressure Tolerance Properties for Long‐Term Management of Bleeding Wound

Injectable wet-adhesive hydrogels represent a promising approach for managing traumatic hemorrhage, yet their clinical translation is often hindered by excessive swelling and inadequate sealing stability. Herein, we report an injectable hydrogel (denoted as PACmC) with rapid coagulation, ultrahigh burst pressure tolerance, and low swelling properties for emergency hemostasis and long-term wound management. PACmC hydrogel is formed by electrostatic self-assembly of aminated carboxymethyl chitosan (ACmCS) into nanoparticles, which are then crosslinked with NHS-activated tetra-arm polyethylene glycol (Tetra-PEG-SS) via rapid NHS-amine coupling, yielding gelation within 22.3 s. The positively charged ACmCS nanoparticles actively aggregate blood components to accelerate hemostasis, while their densely packed network physically restricts water infiltration, resulting in low swelling ratio of only 49.2% within 7 d. For tissue adhesion, the NHS-ester groups on Tetra-PEG-SS covalently bond with amino groups on the wound surface, and ACmCS nanoparticles serve as multivalent crosslinking centers that enhance cohesive strength, together enabling robust wet-tissue adhesion (46.5 kPa) and an ultrahigh burst pressure tolerance of 701 mm Hg. In rabbit and porcine models of hepatic and splenic hemorrhage, PACmC hydrogel achieves rapid hemostasis and maintains long-term sealing compared to clinical hemostats (thrombin powder and gauze), providing a new direction in developing novel hemostatic materials.