Carboxymethyl Chitosan/Oxidized Sodium Alginate‐Based Photoactive Hydrogel With Excellent Self‐Healing and Antibacterial Properties for Dressing

Skin wounds are vulnerable to bacterial infections, which aggravate inflammation and prolong repair time. Traditional antibiotics are susceptible to bacterial resistance. Antibacterial photodynamic therapy (aPDT) employs photosensitizers that generate reactive oxygen species (ROS) upon exposure to specific wavelengths of light. This process is not affected by resistance mechanisms and has gained widespread application in antibacterial treatment. Graphitic carbon nitride (CN) can produce ROS for sterilization under visible light. In this paper, carboxymethyl chitosan (CMCS) served as the hydrogel matrix, while oxidized sodium alginate (OSA) served as the crosslinking agent. CN nanosheets were further incorporated into the hydrogel. The hydrogel was formed through dynamic Schiff base bonds, which conferred remarkable self‐healing properties, thereby enhancing its resistance to external forces and extending its service life. Through antibacterial experiments, it was proved that CMCS, Schiff base structure, and CN achieved a synergistic antibacterial effect under visible light irradiation. The composite hydrogel exhibited bactericidal rates of 93.3% against E. coli and 95.2% against S. aureus . These findings were corroborated by absorbance measurements (OD600) of E. coli . Furthermore, the hydrogel demonstrated favorable moisture retention, swelling capacity, adhesion properties, and excellent biocompatibility, indicating significant potential for applications in wound dressings.