Bacteria-visualizing nano-bactericide with anti-inflammation and wound healing properties for in situ 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 η = 26.80%. In vitro and in vivo studies showed effective NIR photodynamic–photothermal antibacterial effect of SiPc-CMCS against both Gram-positive and Gram-negative bacteria. Furthermore, it realized in situ 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.