A highly sensitive ratiometric fluorescent probe for real-time monitoring sulfur dioxide as the viscosity change in living cells and mice

Sulfur dioxide (SO2), as a signal molecule, has been proved to be involved in many physiological processes. However, its levels will be affected by all kinds of factors. Herein, we specially designed a ratiometric fluorescence probe (PS-1) for the detection of SO2. After responding to SO2, PS-1 showed an obvious enhancement from 1.68 to 168.3 of fluorescence emission ratios at 475 and 643 nm (I-475/I-643). Besides, we found PS-1 exhibited fast response (less 15 s) and low detection limit (17.7 nM), which means PS-1 can monitor a tiny concentration change of SO2 in the cell in real-time. Assuredly, we found that the ratiometric fluorescence changes of PS-1 in the cells pre-incubated with nystatin were more obvious than that of no treated cells. Furthermore, PS-1 was applied for imaging in mice models. These results predictability indicate that internal increasing viscosity can induce increase of sulfur dioxide concentration. Thus, PS-1 could be used to study the relationship between biological microenvironment and sulfur dioxide concentration.