AIE-active photosensitizers for concomitant fluorescence visualization and efficient photodynamic elimination of multidrug-resistant bacteria

Multidrug resistance (MDR) bacterial infection is a serious hazard to human health. Photodynamic therapy (PDT) has been deployed as an emerging tactic to combat pathogenic bacteria, but the development of efficient photosensitizers against MDR bacteria still remains a global challenge. Herein, two near-infrared (NIR) photosensitizers, named TPA-Th and TPA-Ph, which feature aggregation-induced emission (AIE), were constructed and successfully employed for MDR bacteria monitoring and effective elimination. TPA-Th and TPA-Ph exhibited great affinity with MDR G(+) and G(−) bacteria via the electrostatic interaction between the cationic pyridinium segment and the negative bacterial envelope together with hydrophobic forces. Meanwhile, the reinforced D-A effect of the two cationic AIEgens further accelerated the intersystem crossing (ISC) process and enhanced the intramolecular charge transfer (ICT), resulting in the boosted ROS generation capability particularly in the case of predominant hydroxyl radicals. Therefore, superb photodynamic antibacterial performances were achieved for both MRSA and MDR E.coli with a low dose of the AIE photosensitizers. This study provides guidance for the development of high-performance AIE-active PSs with no antibiotic resistance to defeat MDR bacterial infections.