NIR-absorbing organic charge transfer complexes for photothermal antibacterial therapy and wounds healing

Bacterial infections and subsequent inflammation are major obstacles to efficient wound healing and present an increasing clinical challenge due to rising antimicrobial resistance. Photothermal therapy (PTT) offers a non-antibiotic, spatiotemporally controllable strategy to eradicate pathogens. However, the development of promising photothermal agents with high NIR response, biocompatibility and facile preparation is still challenging. Here we report supramolecular assembled donor-acceptor charge-transfer complex (CTC) nanoparticles TPD-TCB (TT NPs) achieved by precise modulation of energy-level engineering between commercially available donor and acceptor molecules. CTC formation yields a narrowed effective HOMO-LUMO gap, which enables TT NPs to exhibit broad NIR absorption extending toward ∼1200 nm and a photothermal conversion efficiency of 38 %. Notably, under 808 nm irradiation TT NPs achieve potent photothermal killing of Gram-positive (90.7 %) and Gram-negative (94.9 %) bacteria in vitro and effectively suppress infection in an in vivo wound model. Additionally, TT NPs + NIR accelerate wound closure by clearing pathogens, resolving inflammation and promoting epidermal differentiation and regeneration. This work establishes a practical and generalizable CTC-based bandgap engineering strategy for creating high-performance organic photothermal agents suitable for antibacterial therapy and wound repair.