A general strategy for high-efficiency live bacteria imaging and targeted phototherapy.

Bacterial peptidoglycan (PG) serves as a unique bacterial signature for imaging and therapeutic targeting, yet existing chemical probes require high concentrations and involve disruptive washing steps. Herein, we report a general strategy for designing high-performance PG probes by incorporating a fluorine-substituted benzenesulfonamide moiety. The structural modification promotes the binding of probes to PBPs and significantly improves their PG-incorporation efficiency. Using this approach, we developed a full-color probe palette spanning the visible spectrum, enabling wash-free imaging of live bacteria at low concentrations with outstanding signal-to-background ratios. Beyond imaging, this strategy further led to the creation of FluoEosinY, a PG-targeted photosensitizer that effectively inactivates antibiotic-resistant bacteria without inducing resistance. In a mouse model of methicillin-resistant Staphylococcus aureus (MRSA)-infected skin wounds, FluoEosinY-mediated antimicrobial photodynamic therapy not only achieved marked reductions in bacterial burden but also accelerated wound healing, with negligible toxicity to host tissues. This versatile design strategy advances both the mechanistic investigation of bacterial cell wall physiology and the development of precision-targeted therapeutics to combat antibiotic-resistant infections.