A multifunctional highly adhesive hydrogel mimicking snail mucus for hemostatic coating

Femur fracture becomes increasingly common due to global population aging. Intramedullary nailing, a widely used treatment for fractures, tends to damage the blood vessels in the bone marrow cavity, which causes substantial hidden bleedings. The application of hydrogels to intramedullary nail hemostasis is limited by the challenges in balancing the adhesion, mechanical strength, and toughness. Inspired by the multi-network structure of snail mucus, which offers strong adhesion in harsh environments via adaptive wet-state contact followed by tight fitting upon dehydration, we developed a dual-network carboxymethyl chitosan (CMCS)-gluconic acid δ-lactone (GDL)-Ca²⁺/polyacrylamide (PAM) (CGC/P) hydrogel. The integration of GDL with CMCS introduces hydroxyl groups to enhance the adhesion of hydrogel and regulated system pH to facilitate the formation of the dynamic CMCS-GDL-Ca²⁺ physical crosslinking network. The chemically crosslinked PAM network further improves the strength and toughness of the hydrogel. As the adhesion strength of the hydrogel can be increased by up to 50.14 times upon dehydration, a stretch-winding and dehydration method is developed to coat intramedullary nails with controllable thickness, effective hemostatic properties, excellent mechanical and adhesion characteristics. In rabbit femoral intramedullary nailing surgery, this system achieves rapid hemostasis and greatly promotes osteogenesis. Our study simultaneously improves the performance regulation contradiction of hydrogel coating, providing a crucial support to promote the application of hemostatic coatings to implantations.