A turn-on fluorescent probe for selective detection of HS in environmental samples and bio-imaging in human breast cancer cells.

A triphenylamine-benzothaizole-based turn-on fluorescent probe TPB-NO2 was designed and synthesized for tracking HS in both environmental and biological samples depending upon the sensing strategy of thiolysis of 2,4-dinitrophenyl (DNP) ether. Due to PET (photoinduced electron transfer), occurring from donor triphenylamine moiety to acceptor DNP moiety, the probe TPB-NO2 itself is very weakly fluorescent and colorless in DMSO/HO solution (1 : 1, v/v; 10 mM HEPES buffer, pH 7.4). But the addition of HS leads to thiolysis of 2,4-dinitrophenyl ether to block the initial PET process and hence it exhibits naked eye detectable turn-on response with bright cyan fluorescence and intense brown color. Not only that, the probe exhibits excellent selectivity over other bio-thiols like Cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), fast response time (<2 min), and high sensitivity with a detection limit of 9.81 nM. Moreover, to explore the practical applicability of our probe we employed it to monitor HS successfully in environmental water samples, solid-state TLC strip study, Quantitative determination of HS in eggs, and in the bioimaging of human breast cancer cells (MDA-MB 231).