Various organic nanoagents have been developed for photothermal therapy (PTT) and photodynamic therapy (PDT) under near-infrared (NIR) irradiation. Among them, small molecule-based nanoagents are very attractive due to their advantages of well-defined chemical structures, high purity, good reproducibility, and easy processability. However, only a few small molecule-based nanoagents have been developed for PDT under NIR irradiation. Moreover, the mechanism of PDT under NIR is still elusive. Herein, a semiconducting small molecule (BTA) with donor-acceptor-donor structure and twisted conformation is developed for PDT/PTT under NIR irradiation. A large π-conjugated electron-deficient unit is used as the core to couple with two electron-donating units, ensuring the strong absorption under 808 nm. Moreover, the donor-acceptor structures and twisted conformation can reduce the energy gap between the singlet and triplet states (∆EST ) to afford effective intersystem crossing, beneficial for reactive oxygen species generation. The mechanism is probed by experimental and theoretical evidence. Moreover, the BTA nanoparticles exhibit excellent biocompatibility and PTT/PDT in vitro performance under NIR irradiation. This provides a strategy for designing highly efficient PDT/PTT molecular materials.

中文翻译：

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结合DA结构和非平面构型，实现高性能的光热和光动力效应。

已经开发了各种有机纳米剂用于近红外（NIR）辐射下的光热疗法（PTT）和光动力疗法（PDT）。其中，基于小分子的纳米剂由于其定义明确的化学结构，高纯度，良好的可再现性和易于加工的优点而非常有吸引力。然而，在近红外辐射下，仅有少数基于小分子的纳米试剂被开发用于PDT。而且，NIR下PDT的机制仍然难以捉摸。在本文中，开发了具有供体-受体-供体结构和扭曲构象的半导体小分子（BTA），用于近红外下的PDT / PTT。大的π共轭电子缺乏单元被用作核心，并与两个供电子单元耦合，确保了在808 nm下的强吸收。此外，供体-受体结构和扭曲构象可以减少单重态和三重态之间的能隙（ΔEST），以提供有效的系统间交叉，有利于活性氧的生成。实验和理论证据探讨了该机制。此外，BTA纳米粒子在NIR辐射下具有出色的生物相容性和体外PTT / PDT性能。这提供了设计高效PDT / PTT分子材料的策略。