Fluorescent probe based on rosamine with pyridinium unit for hydrogen sulfide detection in mitochondria

Two probes that connected ester groups towards rosamine with pyridine unit were prepared in this study. Probe 1a contains 4-acetoxybenzyl group, whereas probe 1b incorporates the 4-(methoxycarbonyl)benzyl moiety. Because of the existence of photoinduced electron transfer (PET) process in these structures, their fluorescence was almost quenched. When hydrogen sulfide was detected by probe 1a, the fluorescence of 1a turned on and there was a 16-fold increase in fluorescence intensity in the 565-800 nm region. In the meantime, the fluorescence quantum yield reached up to 20%. The calculated detection limit of probe 1a was 115.3 nM and it also showed good selectivity and sensitivity to hydrogen sulfide over other species. However, probe 1b had no response towards hydrogen sulfide. Furthermore, the capacity of probe 1a to detect hydrogen sulfide in mitochondria had been demonstrated in living HeLa cells using confocal fluorescence experiments.