Janus Bilayer Hydrogel Dressing With Enhanced Long‐Term Wet Adhesion via Physical‐Covalent Synergistic Mechanism for Oral Mucosal Wound Healing

Ulcers, injuries, and various oral surgical treatments frequently cause damage to the oral mucosa. Current oral wound dressings face critical limitations of short protection time due to their weak wet adhesion capability. To address this issue, we developed a Janus bilayer oral wound dressing (P-N/QCS) with dual functional components. ‌The oral cavity-facing surface of the P-N/QCS film demonstrates effective resistance to salivary erosion, while its opposing surface facilitates integration with biological tissues upon absorption of interfacial fluids or blood. This enables immediate adhesion through physical bonding, subsequently reinforced by molecular entanglement and covalent crosslinking. In vitro tests verified that our dressing exhibited significantly superior wet adhesive strength (53.3 ± 3.7 kPa). The protective duration of P-N/QCS exceeded the commercial product Oral Aid by 521.7% (12 ± 0.5 h vs. 2.3 ± 0.3 h). Additionally, the Janus dressings showed potent hemostatic capability and excellent antibacterial activity. In the model of rat oral ulcer, the adhesive dressings accelerate the healing of the ulcer by suppressing inflammation and promoting epithelialization. In summary, the Janus bilayer oral wound dressing demonstrates promising clinical potential for oral mucosal repair.