Real time precisely tracing the fluctuations of mitochondrial SO in cells during ferroptosis and tissues using a mitochondrial-immobilized ratiometric fluorescent probe.

Mitochondrial sulfur dioxide (SO) plays important roles in physiological and pathological activities. Unfortunately, it is lack of a reliable tool to precisely visualize the mitochondrial SO and elaborate its complicated functions in various cytoactivities. Here we report a mitochondrial-immobilized fluorescent probe PM-Cl consisting of coumarin and benzyl chloride modified benzothiazole, which enables selective visualization of mitochondrial SOvia chemical immobilization. The spectral results demonstrated that probe PM-Cl could respond to SO with high selectivity and sensitivity. Co-localization and the fluorescence of cytolysis extraction verified the excellent mitochondrial targeting and anchoring abilities. Due to the chemical immobilization, probe PM-Cl could firmly retain into mitochondria after stimulation of carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and HO. Significantly, a series of fluorescence images are indicative of capability for detecting the fluctuations of SO in mitochondria during ferroptosis. Furthermore, PM-Cl also could visualize SO in myocardium and muscle tissues after the stimulation of CCCP. Taken together, probe PM-Cl is a very potential molecular tool for precisely detecting mitochondrial SO to explore its complex functions in physiological and pathological activities.