Ultrasound-Guided Injectable Adhesive Hydrogel Enabling Targeted Hemostasis in Deep and Incompressible Wounds.

Conventional hemostatic materials struggle to rapidly control bleeding in deep, incompressible visceral wounds, especially when surgical access is unavailable. In response, we designed an injectable, bio-based hydrogel for ultrasound-guided hemostasis. By chemically modifying natural polymers: hyaluronic acid, chitosan, and polylysine, and inducing a Schiff base reaction between aldehyde and amino groups at room temperature, the hydrogel forms instantly using a dual-syringe system without requiring additional stimuli such as heat or light. After optimizing the formulation, the hydrogel (OPH) achieves a wet adhesion strength of approximately 45 kPa and can withstand a bursting pressure of 123 mmHg in intestinal wounds. The cationic components confer antibacterial activity against Staphylococcus aureus and Escherichia coli. In comparison with commercial hemostats (e.g., Surgicel, gelatin sponges), OPH matches coagulation performance while offering better suitability for deep wounds. In rabbit models of closed and lethal liver injuries, ultrasound-guided in situ injection of OPH hydrogel effectively seals wounds and controls bleeding, reducing surgical pain and complications. The work introduces a high-performance hemostatic platform enabled by a synergistic design: rapid covalent cross-linking, intrinsic cationic activity, and ultrasound-guided precise delivery. Together, these features provide a versatile reference for next-generation trauma-care materials.