A fluorescent probe for specific detection of cysteine in lysosomes via dual-color mode imaging

Biothiols, as part of the reactive sulfur species (RSS), are a class of bioactive molecules that play important physiological roles in human body. However, due to the similarity in structure and reaction sites of biothiols, it is difficult to differentiated detection them at the same time. In this work, a fluorescent probe CM-NBD combined coumarin derivative and 7-nitrobenzofurazan has been developed, which can effectively detect biothiols through simple ether cleavage. Because of a specific location group, CM-NBD can well localize in lysosomes with a high co-localization coefficient. Interesting, due to the weakly acidic environment of lysosomes, Cys can be distinguished from Hcy/GSH and H₂S via dual-color mode. The probe is able not only to image exogenous biothiols but also to discriminate Cys from Hcy/GSH and H₂S in cells and zebrafish model.