Sustained copper-releasing adhesive hydrogel patch promotes optimized scarless tongue wound healing <i>via</i> antioxidative, angiogenic and antifibrotic synergy

Tongue injuries are among the most common acute soft tissue injuries encountered in oral clinical practice. Suturing, as the conventional treatment, often leads to tissue distortion and tension-induced collagen over-deposition, resulting in scarring and restricted tongue mobility. Sutures are also prone to microbial accumulation and provoke inflammation as foreign bodies. In this study, a hydrogel patch specifically designed for the tongue's moist, frequently moving, and richly vascularized environment was developed for better healing of tongue injuries. Briefly, a chitosan-polyacrylic acid-tannic acid hydrogel matrix is loaded with Cu-MOF to form a CPTCu hydrogel, ensuring stable binding and controlled release of copper, while maintaining mechanical compliance with tongue tissue for continuous protection. The CPTCu hydrogel exhibited excellent biocompatibility, achieving a free radical scavenging rate of 73.6% and a bactericidal rate of over 99%. Compared with suturing, the CPTCu hydrogel significantly reduced the collagen volume by 35.9% and enhanced angiogenesis by 103.2%, and also effectively promoted regeneration of local muscle fibers in a rat tongue wound model. These results demonstrate that the CPTCu hydrogel is a promising candidate for optimized scarless tongue healing.