Synergistic Sunlight‐Activated Photodynamic and Near‐Infrared‐Induced Mild Photothermal Therapy for Infected Wound Healing Using Functionalized Nano‐Bi ₂ WO ₆ Composites

ABSTRACT Bacterial infection‐associated inflammation and drug resistance severely impede effective wound healing. Herein, we report a multifunctional Bi ₂ WO ₆ :Yb,Er@CuS@CS nanoplatform that integrates photodynamic therapy (PDT), near‐infrared (NIR)‐triggered mild photothermal therapy (PTT), and Cu ^{2 +} release for infected wound repair. Yb ³⁺ /Er ³⁺ codoping endows Bi ₂ WO ₆ with broadened visible–NIR light absorption and enhanced charge separation, enabling efficient reactive oxygen species generation under simulated sunlight. Surface‐decorated CuS nanoparticles provide robust photothermal conversion under NIR irradiation, while chitosan modification improves biocompatibility and antibacterial performance. The nanoplatform exhibits > 99% antibacterial efficacy against both Methicillin‐resistant Staphylococcus aureus (MRSA) and Escherichia coli and effectively disrupts bacterial biofilms under combined light activation. Importantly, precisely controlled NIR‐induced mild thermal therapy (≈42°C) reprograms macrophage polarization from a proinflammatory M1 phenotype toward a reparative M2 phenotype. Transcriptomic analysis reveals that this immunomodulatory effect is associated with the downregulation of PI3K–Akt, TNF, and NF–κB signaling pathways. In vivo studies using MRSA‐infected wound models demonstrate accelerated wound healing, enhanced angiogenesis, collagen deposition, and minimal systemic toxicity. This work presents a sunlight/NIR‐activated therapeutic strategy that bridges antibacterial treatment and immune‐regulated tissue regeneration for infected wound healing.