ONOO^– Activatable Fluorescent Sulfur Dioxide Donor for a More Accurate Assessment of Cell Ferroptosis

Abstract

Ferroptosis is critical in the treatment of tumor therapies. Thus, monitoring reactive oxygen species (ROS) is of great significance for accurate assessment in ferroptosis without any interference. However, current probes for monitoring ROS during ferroptosis suffer from a drawback in that the probes consume ROS during detection, which inhibits the ferroptosis process and thus affects the accuracy and effectiveness of monitoring the process of ferroptosis. Herein, a new fluorescent donor probe, TFMU-SO 2 D, with the combination of the moiety of the SO 2 donor is designed and synthesized by introducing the aryl boronate moieties that could give it the ability to effectively recognize ONOO − . The released SO 2 could consume excess glutathione and regulate oxidative stress by elevating ROS levels, which would offset the ROS depletion by TFMU-SO 2 D and ensure accuracy in monitoring the ferroptosis process. The experimental results demonstrated that TFMU-SO 2 D possessed satisfactory performance for monitoring ONOO − as well as simultaneously releasing SO 2 in oxidative stress stimulated by monensin and ferroptosis stimulated by erastin and RSL3. Additionally, the capability of SO 2 synergized with ferroptosis to inhibit the viability of cancer cells was demonstrated by the CCK8 assay, which may be due to the fact that SO 2 can potentiate ferroptosis cell death by increasing the ROS level. Overall, these combined results indicated that TFMU-SO 2 D possesses the excellent ability to precisely monitor ONOO − during ferroptosis without interference, which is significant for accurately accessing ferroptosis, cancer treatment, and drug development.

Ratiometric Fluorescent Probe for Super-Resolution Imaging of Lysosome HClO in Ferroptosis Cells

“…We then investigated the efficiency of SRF-HClO in HClO detection during ferroptosis in living cells. At present, RSL3 or erastin is known to induce ferroptosis by inhibiting the activity of glutathione peroxidase 4 (GPX4). , HeLa cells treated with RSL3 (1 μM) or erastin (10 μM), followed by the treatment with SRF-HClO (10 μM) for 0.5 h, showed strong red fluorescent signals from inside the lysosomes with feeble green fluorescent signals (Figure ), indicating that the HClO level increased significantly during the ferroptosis process. However, upon incubating the cells with ferrostatin-1 (Fer-1, a classical ferroptosis inhibitor), the fluorescence intensity of the probe remained basically the same as that of the probe only. , In addition, further validated by flow cytometry, the conclusion was consistent with the above (Figure S8).…”