Near-Infrared Organic Small-Molecule Photosensitizer With O₂ Self-Supply for Cancer Photodynamic-Photothermal...

Tumor hypoxia and heat resistance as well as the light penetration deficiency severely compromise the phototherapeutic efficacy, developing phototherapeutic agents to overcome these issues has been sought-after goal. Herein, a diradical-featured organic small-molecule semiconductor, namely TTD-CN, has been designed to show low exciton binding energy of 42 meV by unique dimeric π-π aggregation, promoting near-infrared (NIR) absorption beyond 808 nm and effective photo-induced charge separation. More interestingly, its redox potentials are tactfully manipulated for water splitting to produce O₂ and reduction of O₂ to generate O₂ ^•-. Besides, both ultrafast internal conversion and high-frequency stretching vibrational relaxation of C≡N bonds favor photothermy. Accordingly, TTD-CN nanoparticles have been prepared to exhibit spatiotemporally-synchronous O₂ and O₂ ^•- generation and 63.2% photothermal conversion under 808 nm laser irradiation for high-efficient photodynamic and photothermal synergistic therapy. These findings successfully realize NIR light-triggered spatiotemporally-synchronous O₂ self-supply, type-I photosensitization and superior photothermy in an organic small-molecule phototherapeutic agent, significantly boosting the development of phototherapy.