Synergistic Photodynamic and Photothermal Antibacterial Therapy Based on a Conjugated Polymer Nanoparticle-Doped Hydrogel

Herein, we have developed a composite antibacterial hydrogel with photodynamic therapy (PDT) and photothermal therapy (PTT) antibacterial capabilities, triggered by white light and NIR light irradiation. A water-insoluble conjugated polymer (PDPP) with photothermal ability was prepared into nanoparticles by the nanoprecipitation method, and the cell-penetrating peptide TAT was grafted on the surface of the nanoparticles. Based on our previous work that developed a hybrid hydrogel with an enhanced PDT effect from polyisocyanide (PIC) hydrogel and cationic conjugated polythiophene (PMNT), PDPP nanoparticles (CPNs-TAT) with photothermal ability are introduced to realize the synergistic antibacterial effect of PDT and PTT. Using the PIC hydrogel to combine PIC and CPNs-TAT has the following advantages. First, the PIC hydrogel can regulate the aggregation state of PMNT, making it better dispersed and improving its capacity of reactive oxygen species (ROS) production. Second, CPNs-TAT can be uniformly dispersed in the PIC hybrid, thereby avoiding the toxicity caused by too high local concentration, achieving a uniform increase in system temperature, and enhancing the therapeutic effect of PTT. Third, the PIC hybrid has the synergistic treatment effect of PDT and PTT. The PIC hybrid intelligently regulates its antibacterial ability through white light and NIR light, which can be used in the white light and NIR light areas. When irradiated with white light and NIR light sequentially, synergistic PDT and PTT exhibit stronger antibacterial ability than PDT or PTT alone. The combination of two antibacterial methods realizes the dual-control antibacterial hydrogel of PDT and PTT and provides an antibacterial mode based on PIC hybrids. Therefore, the PIC hybrids are promising as an antibacterial excipient for clinical wounds.