Near-Infrared Conjugated Oligomer for Effective Killing of Bacterial through Combination of Photodynamic and Photothermal Treatment

In recent years, phototherapeutic strategies including photodynamic therapy (PDT) and photothermal treatment (PTT) have attracted extensive interest in biological and medical applications. To achieve high efficiency in therapy, it is crucial to develop promising agents possessing synergistic PDT and PTT effects, especially those triggered by single-wavelength near-infrared (NIR) light. Herein, a low-bandgap fluorene-based conjugated oligomer OF-Green-N with a donor-acceptor-donor (D-A-D) structure was synthesized, which had a broad absorption in both the visible and NIR range. Upon irradiation by 808 nm laser, the oligomer displayed a good photothermal capacity with a conversion efficiency of 37.7%, together with simultaneous photodynamic behavior which produced reactive oxygen species. By incubation with Escherichia coli, OF-Green-N was demonstrated to possess outstanding antibacterial activity owing to the synergistic effects of PDT/PTT. Moreover, its green fluorescence excited by 420 nm light also provides an opportunity for imaging-guided treatment.