Bacteria-visualizing nano-bactericide with anti-inflammation and wound healing properties for <i>in situ</i> NIR phototherapeutic strategies

Anti-infection and wound healing are critical to the survival of patients with skin burns or postoperative infections, and there is an urgent clinical demand for drugs that combine anti-inflammatory and tissue recovery functions, especially new drugs that can overcome the inherent drug resistance of bacteria to conventional antibiotics. In this work, a phototherapeutic bactericide SiPc-CMCS was constructed by covalently grafting silicon phthalocyanine onto natural carboxymethyl chitosan. SiPc-CMCS ingeniously exhibited combined effects of photodynamic and photothermal therapies with wound healing effects for synergistic anti-inflammation and wound recovery, without the constraints of dosage and drug resistance. Two ROS, namely, O₂˙^- and ¹O₂, which belong to type I and type II photodynamic pathways, respectively, were observed, and SiPc-CMCS exhibited a photothermal conversion efficiency of <i>η =</i> 26.80%. <i>In vitro</i> and <i>in vivo</i> studies showed effective NIR photodynamic-photothermal antibacterial effect of SiPc-CMCS against both Gram-positive and Gram-negative bacteria. Furthermore, it realized <i>in situ</i> wound healing and fluorescence bacteria visualizing capability. These data prove that SiPc-CMCS is a potential bacteria-readout-guided NIR phototherapeutic bactericide, which is effective against both aerobic and anaerobic bacterial infections, and it possesses excellent wound-healing capability for treating skin burns and postoperative infections.