Molecular Engineering of AIE-Active Photosensitizers with High Biosafety for Effect Extracellular Antibacteria

Developing versatile photosensitizers to actualize selective antibacteria over normal cells presents an appealing yet significantly challenging task. In this study, a novel photosensitizer named DMMA-SCPI is rationally designed and facilely synthesized, which is demonstrated as a type-I photosensitizer featured by aggregation-induced emission tendency. DMMA-SCPI is capable of effectively eliminating both Galanz positive bacteria and Galanz negative bacteria in vitro and in vivo, and showed insignificant injury to normal cells and tissues, probably resulting from its pyridinium halide that has stronger adsorption property on negatively charged bacteria compared to normal cells, as well as its suitable antimicrobial activity. The antimicrobial activity of pyridinium salt type photosensitizer depends on the adsorptive activities on the surface of bacterial cells as well as the antimicrobial activity of the reactive oxygen species (ROS). Among three photosensitizers, DMMA-SCPI has better water solubility, which provides greater surface activity to adsorb bacteria. Moreover, DMMA-SCPI produces more superoxide anion radicals as ROS, which has proper antimicrobial activity with high biosafety for effect extracellular antibacteria.