A bifunctional fluorescent probe for imaging lipid droplets polarity/SO2 during ferroptosis

The polarity and SO2 play a key role in the cellular microenvironment. However, fluorescence probes that detect both polarity and SO2 have not been reported. Herein, it is crucial to develop a reliable detection tool to selectively and sensitively monitor the polarity and SO2 of lipid droplets (LDs). In this paper, we designed a novel fluorescent probe TPA-SO2 with introducing triphenylamine structure. TPA-SO2 can sensitively detect the polarity decrease accompanied by red fluorescence emission at 610 nm, and its C = C double bond is sensitive to response SO2 with a turn-on blue emission at 437 nm. Localization experiments have shown that TPA-SO2 can specifically target cellular LDs. Fluorescence imaging studies revealed that TPA-SO2 can monitor exogenous SO2 in HeLa cells. Most important of all，it is the first probe which could detect SO2 and LDs polarity at the same time during ferroptosis process. TPA-SO2 can serve as an indicator agent for polarity/SO2 imaging to offer precise and efficient physiological mechanisms.