LAUSR

Heat stroke can cause organism damage and even death. Early understanding of the mechanism of heat cytotoxicity can prevent or treat heat stroke related diseases. In this work, Probe Ly-NT-SP is synthesized, characterized and used for SO2 detection in lysosomes. PBS solutions of probe Ly-NT-SP at pH 5.0 presents a marked broad emission band in the green zone (535 nm). After UV irradiation the spiropyran group in Ly-NT-SP isomerizes to the merocyanine form (Ly-NT-MR) which presented a weak redshifted emission at 630 nm. Besides, photo-controlled isomerization of Ly-NT-SP to Ly-NT-MR generated a C=C─C=N+ fragment able to react, through a Michael addition, with SO2 yielding a highly emissive adduct with a marked fluorescence in the green channel (535 nm). In vitro studies showed a remarkable selectivity of photo-activated Ly-NT-MR to SO2 with a limit of detection as low as 4.7 µM. Besides, MTT viability assays demonstrated that the Ly-NT-SP is non-toxicity to HeLa cells and can be used to detect SO2 in lysosomes. Taking advantage of this, the sensor is successfully applied to image increasing SO2 values in lysosomes during heat shock for the first time. Moreover, we also confirmed that the increased SO2 can protect the small intestine against damage induced by heat shock through regulating oxidative stress in cells and mice.