An intelligent photosensitizer that selectively kills Gram-positive pathogenic cocci while preventing harm to beneficial bacilli

The skin microbiota is an inseparable component of the skin barrier structure, which participates in the stabilization or impairment of the barrier function as well as the development of many skin diseases. In order to maintain the stability of skin bacteria community structure, people pay more and more attention to protecting probiotics, such as bacilli, and killing pathogens, such as Gram-positive cocci. We herein report a negatively charged photosensitizer TPA-3NBA with aggregation-induced emission (AIE) characteristics, which was synthesized by one-step reaction, can selectively and rapidly stain (within 0.5 min) and effectively kill Gram-positive cocci (killing 6.0 log10 of Staphylococcus aureus at a concentration of 1 μM) without affecting bacilli under white light irradiation. This selective bacterial imaging makes it possible to quickly identify locally bacterial infection. Furthermore, the normal concentration of divalent ion (Ca2+) in human body can significantly promote the absorption of TPA-3NBA by Gram-positive cocci, thus improving its antibacterial activity. To the best of our knowledge, this is the first photosensitizer to be reported with good performance in selective bacterial imaging and removal of Gram-positive pathogenic cocci, indicating its potential application prospect in targeted antimicrobial therapy.