A novel colorimetric and ratiometric fluorescent probe for visualizing SO2 derivatives in environment and living cells

Monitoring sulfur dioxide (SO2) derivatives in environment is of great significance due to their harmful effects to the environment and human health. In this study, a fluorescent probe (CZBT) for SO2 derivatives was prepared from 9-ethyl-9H-carbazole-3,6-dicarboxaldehyde and 2-methyl-benzothiazolium, which displayed a noticeable color change from yellow to colorless along with a remarkable fluorescence change from yellow to blue in response to HSO3-. The probe could quantitatively determine the concentration of HSO3- with excellent selectivity, high sensitivity and low limit of detection. H-1 NMR and HR-MS spectra demonstrated that a selective 1, 4-nucleophilic addition occurred on the bridge double bond in CZBT. The probe was successfully used to determine the SO2 derivatives in several real water samples with good recovery. Furthermore, the probe was employed for monitoring the level of intracellular HSO3- in HeLa (human cervical cancer) cells by fluorescence imaging. These results indicated that CZBT has a good capability for monitoring SO2 derivatives in environment and living cells.