A Ratio Fluorescent Probe for the Detection of Bisulfite and Its Application in Living Cells

Sulfur dioxide derivatives play excellently vital roles in numerous essential physiology and pathology processes of living systems. The abnormal levels of bisulfite/sulfite (HSO 3 − /SO 3 2− ) may cause the occurrence of a series of diseases, including acute symptoms of respiratory disease, brain damage, neurological disorders, cardiovascular disease, and even cancer. Therefore, it is necessary to develop simple and effective methods to monitor the fluctuation of HSO 3 − /SO 3 2− . Herein, a novel ratiometric fluorescent probe ((E)‐3‐(2‐(4‐formylstyryl)‐3,3‐dimethyl‐3H‐benzo[g]indol‐1‐ium‐1‐yl)propane‐1‐sulfonate, Cy‐DBPS ) is devised to trace HSO 3 − /SO 3 2− in living cells. In the presence of HSO 3 − /SO 3 2− , the large conjugated system is destroyed by triggering the Michael addition reaction, which further induce the probe to emit a ratio of fluorescence signal. Furthermore, the probe can quickly respond to HSO 3 − /SO 3 2− within 120 s and exhibits low detection limit, which provides the possibility of sensitive and real‐time detection of HSO 3 − /SO 3 2− in living cells. Based on the unique advantages of high selectivity, negligible cytotoxicity and great biocompatibility, Cy‐DBPS can effectively detect exogenous and endogenous HSO 3 − /SO 3 2− in HepG2 and HeLa cells. The outstanding properties of the probe Cy‐DBPS provided a great potential for the further valuable application in living cells and even deeper biological applications for HSO 3 − /SO 3 2− detection.