Ultrastable Near-Infrared Conjugated-Polymer Nanoparticles for Dually Photoactive Tumor Inhibition

It is highly desired that satisfactory photoactive agents with ideal photophysical characteristics are explored for potent cancer phototherapeutics. Herein, bifunctional nanoparticles of low-bandgap donor-acceptor (D-A)-type conjugated-polymer nanoparticles (CP-NPs) are developed to afford a highly efficient singlet-to-triplet transition and photothermal conversion for near-infrared (NIR) light-induced photodynamic (PDT)/photothermal (PTT) treatment. CP-NPs display remarkable NIR absorption with the peak at 782 nm, and perfect resistance to photobleaching. Photoexcited CP-NPs undergo singlet-to-triplet intersystem crossing through charge transfer in the excited D-A system and simultaneous nonradiative decay from the electron-deficient electron acceptor isoindigo derivative under single-wavelength NIR light irradiation, leading to distinct singlet oxygen quantum yield and high photothermal conversion efficiency. Moreover, the CP-NPs display effective cellular uptake and cytoplasmic translocation from lysosomes, as well as effective tumor accumulation, thus promoting severe light-triggered damage caused by favorable reactive oxygen species (ROS) generation and potent hyperthermia. Thus, CP-NPs achieve photoactive cell damage through their photoconversion ability for synergistic PDT/PTT treatment with tumor ablation. The proof-of-concept design of D-A-type conjugated-polymer nanoparticles with ideal photophysical characteristics provides a general approach to afford potent photoactive cancer therapy.