Water-soluble improved NIR ratiometric fluorescent probe for specific imaging sulfur dioxide in cancer cell membranes and living mice

The comprehensive understanding of the mechanism between gas messenger molecules and cell membrane microenvironment is of great significance for basic biology research. Sulfur dioxide (SO2), as a vital gas molecule, is of great value in the permeability and fluidity of cell membranes. However, monitoring of sulfur dioxide in cell membranes with high temporal and spatial resolution remains a challenge. Herein, we designed and synthesized a ratiometric probe CMCB based on coumarin and indole sulfonate platform. The unsaturated CC is selected as the reaction site of SO2, utilizing sulfonic acid groups to increase CMCB hydrophilicity to achieve efficient targeting of cell membranes. The probe CMCB features a good cells membranes targeting and a NIR emission (720 nm). Interestingly, the probe showed low detection limit, high selectivity and specificity of targeting cell membranes. We expect that this probe will serve as an ideal tool in studying gas messenger molecule on cytomembrane in vivo.