Discriminating Cys from GSH/H2S in vitro and in vivo with a NIR fluorescent probe

Biothiols play a prominent role in physiological and pathological processes as reactive sulfur species (RSS), which are closely related to the pathways of metabolism of living animals. By reason of their similar chemical structure and properties, it is challenging to distinguish biological mercaptans from each other in living systems. Herein, a NIR probe (NN) for effectively distinguishing cysteine (Cys) from glutathione (GSH)/hydrogen sulfide (H2S) using a dual-channel responsive mode in vitro and in vivo were developed. NN performs no fluorescence characteristics in the visible to NIR range. Upon treatment with Cys, the system generates significant fluorescence enhancement in both green and near infrared emission bands, while encounter of GSH/H2S generates the increasing of fluorescence only in the near infrared region. In addition, the probe NN also exhibits excellent selectivity, stability, low cytotoxicity as well as low detection limit (0.05 μM for Cys, 0.11 μM for GSH and 0.02 μM for H2S). More importantly, integrating these excellent attributes into a single molecule make it possible to discriminate Cys from GSH/H2S in vivo for the first time.