4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BDPI)-Triphenylphosphine Nanoparticles as a Photodynamic Antibacterial Agent

Photodynamic therapy (PDT) has aroused great interest in antimicrobial treatment because it can take advantage of the reactive oxygen species (ROS) generated by photosensitizers under laser irradiation to kill bacteria efficiently without causing drug resistance. Herein, we designed a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) photosensitizer (BDPI-TPP) with a triphenylphosphine (TPP) cation for highly efficient PDT against bacteria. The prepared BDPI-TPP nanoparticles (BDPI-TPP NPs) can adhere to the surface of bacteria via electrostatic interactions between the positively charged BDPI-TPP NPs and the negatively charged bacterial membranes. More importantly, BDPI-TPP NPs exhibit a potent antibacterial effect with a small minimum inhibitory concentration (MIC) of only 0.3 μg mL–1 attributing to both the positive charges and the photodynamic activity. What is more, BDPI-TPP NPs can also damage the preformed biofilm and effectively promote wound healing. This work highlights the potential of designing cationic photosensitizers as highly efficient antimicrobial agents.