Dual-Fluorophore and Dual-Site Multifunctional Fluorescence Sensor for Visualizing the Metabolic Process of GHS to SO2and the SO2Toxicological Mechanism by Two-Photon Imaging

As a momentous gas signal molecule, sulfur dioxide (SO2) participates in diverse physiological activities. Excess SO2will cause an apparent decrease in the level of intracellular glutathione (GSH), thereby damaging the body’s antioxidant defense system. In addition, endogenous SO2can be generated from GSH by reacting with thiosulfate (S2O32–) and enzymatically reduced to cysteine (Cys), a synthetic precursor of GSH. In view of their close correlation, a two-photon (TP) mitochondria-targeted multifunctional fluorescence sensor Mito-Na-BPwas rationally designed and synthesized for detecting SO2and GSH simultaneously. Under single-wavelength excitation, the sensor responded to GSH-SO2and SO2-GSH continuously with blue-shifted and green fluorescence-enhanced signal modes, respectively, not just to GSH (enhanced) and SO2(quenched) at 638 nm with a completely converse response tendency. Given its favorable spectral performance (high sensitivity, superior selectivity, and fast response rate) at physiological pH, Mito-Na-BPhas been successfully applied in monitoring the level fluctuation of GSH affected from high-dose SO2and visualizing in real time the metabolic process of GSH to SO2by TP imaging. It is expected that this research will provide a convenient and efficient tool for elucidating intricate relationships of GSH and SO2and facilitate further exploration of their functions in biomedicine.