A near-infrared light-responsive multifunctional nanocomposite hydrogel for efficient and synergistic antibacterial wound therapy and healing promotion

The development of new multi-functional dressing materials that effectively combine excellent antibacterial and wound healing promotion properties are highly desirable in modern biomedical research and clinical practice. In this study, a new near-infrared photo-responsive dressing material (HG1-CW) was fabricated based on a dodecyl-modified and Schiff base-linked chitosan hydrogel, a photothermal agent (WS2 nanosheets), and an antimicrobial drug (ciprofloxacin). This nanocomposite dressing possesses the advantages of being injectable, self-adapting, rapidly molding, and has good tissue adherence and excellent biocompatibility. The positive charge, macropore, and alkyl chain of the hydrogel helped to capture and restrict the bacteria. Under the irradiation of near-infrared light, the WS2 nanosheets produced a large amount of heat and simultaneously, the antibiotic was triggered to release in an on-demand fashion at the wound site, leading to the bacterial death. This synergistic therapy combining the photothermal effect and the spatially and temporally controlled drug release effectively avoided the shortcomings of each of the two individual treatment modes, and the outstanding sterilizing effect was verified by both the in vitro antibacterial tests and an S. aureus-infected mouse wound model. Furthermore, the dressing nanocomposite showed a good anti-oxidation activity, which could effectively eliminate the inflammatory responses triggered by the dead bacteria left in the infected area, avoid secondary damage to the wound tissue, and promote wound healing. This multifunctional dressing demonstrates good potential in clinical applications.