Detecting Changesin Singlet Oxygen and Viscosityduring Apoptosis-Ferroptosis Mediated Photodynamic Therapy and EstablishingVisual Imaging of Fatty Liver

Cancer is a serious global health threat, and photodynamic therapy (PDT) is an effective treatment method for cancer. This therapy works by generating a large amount of singlet oxygen (¹O₂) under the influence of oxygen and light, which induces apoptosis in tumor cells, leading to their destruction. However, the resistance of cells to apoptosis limits the development of PDT, and thus the combination of ferroptosis and apoptosis provides a new perspective for PDT. During PDT and ferroptosis, the levels of ¹O₂ and the microenvironment (viscosity) within cells often change. To address this, this study developed a novel fluorescent probe, <b>NI–QM-OH</b>, based on the TICT–ICT effect, capable of monitoring changes in ¹O₂ and viscosity during PDT. The probe exhibits excellent selectivity, high sensitivity, and a low LOD (0.38 μM), and has been successfully applied for bioimaging in HepG2, HeLa, and MCF-7 cells, as well as for monitoring viscosity and ¹O₂ levels in zebrafish. Most importantly, <b>NI–QM–OH</b> also enables the visualization of the diagnosis of fatty liver disease (both alcoholic and nonalcoholic).