Breaking the ΔE ST Barrier: Triazole‐AIE Nanoplatforms with Near‐Degenerate Excited States for Combating Drug‐Resistant Bacteria

Abstract Antibiotic‐resistant bacterial infections necessitate innovative antimicrobial modalities. Here, three triazole‐based aggregation‐induced emission (AIE) photosensitizers— TPTSM , SMTB , and TBLSM —are engineered by judicious donor–acceptor tuning and π‐bridge modulation to enforce near‐degenerate S 1 /S 2 and T 1 /T 2 excited states, thereby transcending the conventional reliance on a minimal ΔE ST for efficient intersystem crossing (ISC). Theoretical calculations show that TBLSM exhibits pronounced spin–orbit coupling and multiple quasi‐resonant ISC channels despite an S 1 –T 2 energy gap of 1.08 eV, culminating in a white‐light‐activated singlet‐oxygen quantum yield (Φ Δ ) of 0.97. To enhance photostability and facilitate biological delivery, TBLSM self‐assembles with Pluronic F127 into stable nanoparticles. In vitro, these nanoparticles eradicate 99% of Escherichia coli , and in a murine skin infection model established with kanamycin‐resistant E. coli ( Kan R ‐ E. coli ), they nearly abrogate bacterial burden and markedly accelerate wound closure, all while causing negligible dark toxicity and showing excellent biocompatibility. By surmounting the ΔE ST constraint through excited‐state degeneracy, this compact strategy delivers a robust platform for white‐light‐driven photodynamic antibacterial therapy.