A water soluble ratiometric fluorescent probe for targeting SO2 in mitochondria based on conjugated biquinolines

Despite the unprecedented development of SO2 fluorescent probes in the past five years, the water-solubility of these probes is still an important factor related to their practical application. In previous work, we have studied SO2 detection by coupling quinoline and coumarin. Although the water solubility of the probe was improved, SO2 detection in a 100% aqueous medium was not fully achieved. Therefore, based on the previous system, we conjugated two quinolines to realize a 100% water-soluble sulfur dioxide fluorescent probe. The Probe showed a large Stokes shift (170 nm). Besides, the Probe could respond to SO2 within 1.5 min with high selectivity and sensitivity (LOD = 0.29 μM). In addition, fluorescence co-localization studies suggested that the Probe could be used for monitoring SO2 in the mitochondria of HeLa cells and living mice. It is believed that such an excellent probe will have a wide application prospect in the future.