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

Abstract

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.