An AIE-Active Cyclometalated Iridium(III) Photosensitizer for Selective Discrimination, Imaging, and Synergistic Elimination of Gram-Positive Bacteria

A platform integrating selective discrimination, imaging, and synergistic elimination of Gram-positive bacteria is urgently needed to address the problem of bacterial infection, especially those resulting from Gram-positive bacteria,. Aggregation-induced emission materials (AIEgens) have shown great promise for antimicrobial applications. Herein, three positively charged AIE-active cyclometalated iridium photosensitizers (Ir1–3) were rationally designed and synthesized. Selective discrimination and imaging of Gram-positive bacteria among Gram-positive bacteria, Gram-negative bacteria, and fungi were achieved with Ir1–3. Among three AIE-active cyclometalated iridium photosensitizers, Ir1 had the best antibacterial activity owing to the monoaromatic substituent of phenanthroline imidazole ligand to the main ligand, eliminating Gram-positive bacteria through its inherent antibacterial mechanism and bacterial photodynamic inactivation. Furthermore, Ir1 altered Gram-positive bacterial gene expression and was successfully applied to S. aureus-infected wound treatment. Due to the interaction between lipoteichoic acids (LTA) and our iridium-based AIEgens, our AIEgen photosensitizers realized selective discrimination, imaging, and synergistic elimination of Gram-positive bacteria.