Double-Network Hydrogel Based on Methacrylated Chitosan/Hyaluronic Acid Coacervate for Enhanced Wet-Tissue Adhesion

Developing robust wet tissue adhesives remains challenging due to interfacial water and irregular surfaces. While polyelectrolyte coacervates demonstrate promising hydrophobic/fluidic properties for wet adhesion, their low cohesion limits practical applications. Herein, a wet tissue bioadhesive based on coacervates formed from low- molecular-weight methacrylated chitosan (CSMA) and hyaluronic acid (HA) is reported. These homogeneous and transparent coacervates displayed high solid content (∼18.0%), fluidity (∼10⁵ mPa·s), and tunable mechanical properties. Upon application to wet tissue surfaces, the coacervate can be photo-cross-linked to form a double-network hydrogel in situ, resulting in improved cohesion and durable adhesion. The resulting CSMA-HA hydrogel demonstrated robust adhesion to tissues, with a bursting pressure of 374 mmHg. Remarkably, the bursting pressure can be further enhanced (∼623 mmHg) after 24 h of PBS immersion due to dynamic bond reorganization and low swelling. The demonstrated stability under physiological conditions and robust wet adhesion position CSMA-HA coacervates as a transformative platform for tissue adhesive applications.