A fluorescent probe for detecting and imaging sulfur dioxide derivatives in vitro and in vivo.

Sulfur dioxide (SO2), an important gaseous signaling molecule, takes part in multiple pathological and physiological processes and plays a vital role in complex biological systems. However, the pathogenesis of many serious diseases, such as respiratory diseases, cardiovascular disorders and neurological diseases, resulting from excessive inhalation of SO2 remains unclear. Therefore, it is significant to develop reliable analytical methods to effectively and concretely monitor SO2 derivatives in living systems. In this study, a fluorescent probe BCy-SO2 was designed and synthesized for sensing SO2 derivatives in vitro and in vivo. The developed probe BCy-SO2 is based on the semicarbocyanine fluorescent group BCy linked to benzaldehyde, and the -CHO group can be used for the detection of SO2 derivatives. SO2 dissociates readily in water to bisulfite (HSO3-). As expected, HSO3- disrupts the photoinduced electron transfer (PET) of the probe BCy-SO2 to produce fluorescence, which is characterised by fast reaction time, low detection limit and high sensitivity. Our probe BCy-SO2 has been successfully designed for the detection of SO2 derivatives (HSO3-) in living cells, zebrafish and mice. We envisage that BCy-SO2 could be a powerful and attractive chemical tool to detect SO2 derivatives in biological specimens.