A pH-Responsive Hydrogel Integrating Carbon Dots and Functionalized MXene with Visual Indication and Photothermal-Redox Regulation of Infected Wound Repair

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Persistent bacterial biofilms pose a formidable obstacle to the clinical management of infected wounds, excessive oxidative stress and dysregulated inflammatory responses. Herein, a pH-responsive multifunctional hydrogel (QS@CD-MXCMC) was fabricated by integrating carbon dots (CDs) and CuMn-curcumin metal-polyphenol network loaded MXene (MXCMC) nanosheets into a quaternary ammonium chitosan-sodium alginate (QS) hydrogel matrix. The pH-responsive fluorescence of CDs enables visual indication of wound microenvironmental changes, providing a convenient approach for monitoring wound status. Meanwhile, the MXCMC nanosheets combine the photothermal activity of MXene with the antioxidant activity of the CuMn-curcumin metal-polyphenol network, enabling NIR-triggered bacterial and biofilm elimination while alleviating excessive oxidative stress. Furthermore, the hydrogel modulated the macrophage response by favoring the transition toward the anti-inflammatory M2 phenotype, thereby creating a more conducive microenvironment for tissue repair. In a full-thickness wound model infected with MRSA, QS@CD-MXCMC combined with NIR irradiation markedly decreased the bacterial load and facilitated tissue regeneration, as evidenced by enhanced re-epithelialization, collagen accumulation, and neovascularization. These therapeutic effects ultimately resulted in accelerated wound closure. By integrating visual indication with antibacterial and microenvironment-regulating functions in a single hydrogel, QS@CD-MXCMC provides an integrated strategy for infected wound management.