Discriminative detection of cysteine/homocysteine and glutathione in HeLa cells by dual-channel fluorescent probe

Biothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play important roles in various physiological and pathological processes. However, it is still a great challenge to selectively detect Cys/Hcy and GSH in biological samples due to the similarity of structures and re-activities of these biothiols. In this paper, a new dual-channel near infrared-7-nitro-1,2,3-benzoxadiazole ( NIR-NBD ) fluorescent probe has been developed for the discriminative detection of Cys/Hcy and GSH. The probe is composed of two functional parts: a near-infrared dye of dicyanoisophorone, as fluorophore precursor, and NBD as both fluorophore precursor and sensing group. It was observed that NIR-NBD probe displayed two different fluorescent signals in response to biothiols, green-red for Cys/Hcy and red for GSH. It also showed a near infrared emission (756 nm), low detection limit, fast response, high stability, selectivity and sensitivity. Furthermore, NIR-NBD was effectively applied for the discriminative detection of Cys/Hcy and GSH in HeLa cells .