A NIR emission fluorescence probe for visualizing elevated levels of SO2 in cancer cells and living tumor

Cancer is a fatal disease that poses a serious threat to human health and life. However, it remains an enormous challenge for detecting tumors due to the limitations of biomarkers and monitoring tools. According to research findings, tumors are closely associated with elevated levels of cysteine (Cys), which is converted to dioxide (SO2) in cysteine dioxygenase and aspartate aminotransferase, presumably causing elevated SO2 in tumor. Based on the aforementioned reasons, an NIR fluorescence probe, DCM-SO2, was correspondingly designed to identify SO2 in tumors. In the mimetic physiological condition, the probe performed admirably in identifying SO2 with a large Stokes Shift (156 nm), marvelous selectivity, and remarkable interference resistance. In addition, it worked successfully in observing variations of exogenous/endogenous SO2 in Hela cells and distinguishing cancer cells from normal cells. More importantly, the higher concentrations of SO2 in tumor than in normal tissue were visualized with the support of fluorescence imaging technique, implying a remarkably close relationship between tumor and the overexpression of SO2.