An AIE Photosensitizer with Simultaneous Type I and Type II ROS Generation: Efficient Bacterial Elimination and Hypoxic Tumor Ablation

Aggregation induced emission (AIE) photosensitizers have attracted great attention due to their good performance in photodynamic therapy (PDT). However, the therapeutic effect of AIE photosensitizer is often highly dependent on the biological microenvironment because it is difficult to produce type I and type II reactive oxygen species (ROS) simultaneously. Herein, an electron-rich anion-pi(+) AIEgen Pys-QM-TT is reported, which is capable of highly generating type I and type II ROS and realizing near-infrared fluorescence imaging synchronously. In the rational design of AIE photosensitizer, the strong electron-donating triphenylamine unit, pi-bridge thiophene and electron-withdrawing pyridinium salt unit can enhance the D-pi-A behavior, thereby improving the intramolecular charge transfer effect and extending the wavelength. Meanwhile, the powerful D-pi-A effect is supposed to reduce increment ES-T and promote the intersystem crossing processes, thus increasing the generation of ROS. In addition, the negatively charged anion in pyridinium salt group provides an electron-rich environment for the excited photosensitizer, so as to promote electron transfer to generate type I ROS. Therefore, Pys-QM-TT can not only generate type I and type II ROS simultaneously with weak environmental dependence, but also effectively inhibit bacterial infections and ablate tumor tissue by promoting tumor cell apoptosis, inhibiting tumor cell proliferation and anti-angiogenesis.