Aggregation-Induced Emission-Active Toroidal Micelles from a Conjugated Polymer: A Selective Phototheranostic Nanoplatform for Targeting Gram-Positive Bacteria

Developing advanced antimicrobial photosensitizers that target bacteria precisely is highly desirable but challenging. Traditional photosensitizers demonstrate reduced reactive oxygen species (ROS) production and quenched fluorescence upon aggregation in water, significantly affecting their phototheranostic performance. In this study, water-dispersible toroidal micelles (TPE-BT Mic) with excellent fluorescence properties and ROS generation are prepared by using aggregation-induced emission (AIE)-active conjugated polymer TPE-BT as the photosensitizer and vancomycin-decorated Pluronic F127 as both the encapsulating and targeting material. The stable toroidal micelles not only promote the aggregation of TPE-BT and induce an AIE effect but also improve its water dispersibility and biocompatibility. TPE-BT Mic with vancomycin targeting groups selectively bind to Gram-positive bacteria Staphylococcus aureus (S. aureus) via the d-alanyl-d-alanine terminus of peptidoglycan, showing strong bioimaging performance. They achieved over 97% killing efficiency for S. aureus with low white-light irradiation (20 mW/cm²). Thus, TPE-BT Mic are promising for treating Gram-positive bacterial infections and offer an innovative approach for creating effective photosensitizers to combat the menace of drug resistance.