Time-dependent Photodynamic Therapy for Multiple Targets: A Highly Efficient AIE-active Photosensitizer for Selective Bacterial Elimination and Cancer Cell Ablation

Pathogen infection and cancer are the two major human health problems. In this work, we achieved an organic salt photosensitizer (PS), called 4TPA-BQ with aggregation-induced emission feature <i>via</i> one-step reaction. Owing to the aggregation-induced reactive oxygen species generation effect and sufficient small ΔE<sub>ST</sub>, 4TPA-BQ shows a satisfactorily high <sup>1</sup>O<sub>2</sub> generation efficiency of 97.8%. <i>In vitro</i> and <i>in vivo</i> experiments confirmed that 4TPA-BQ exhibited potent photodynamic antibacterial performance against ampicillin-resistant <i>Escherichia coli</i> with good biocompatibility in a short time (15 min). When the incubation time persisted long enough (12 h), cancer cells were ablated efficiently, leaving normal cells essentially unaffected. This is the first reported time-dependent fluorescence-guided photodynamic therapy in one individual PS for ordered and multiple targeting by varying the external conditions. This can update the design principle of efficient PSs in potential clinical applications.