A Triple-Emission Fluorescent Probe for Discriminatory Detection of Cysteine/Homocysteine, Glutathione/Hydrogen Sulfide, and Thiophenol in Living Cells

Thiols, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH), hydrogen sulfide (H 2 S), and thiophenol are metabolically correlated with each other via redox reactions. As a result of the similarity of chemical properties between Cys, Hcy, GSH, H 2 S, and thiophenol, it is very challenging to develop an effective methodology to differentiate them. In this work, a triple-emission fluorescent probe, NCQ, was reported for the simultaneous detection of Cys/Hcy, GSH/H 2 S, and thiophenol with high sensitivity and selectivity. The solution of NCQ displayed distinct fluorescent signals toward Cys/Hcy, GSH/H 2 S, and thiophenol: blue and green for Cys/Hcy, blue for GSH/H 2 S, blue and red for thiophenol. Through the blue–green–red emission color combination, Cys/Hcy, GSH/H 2 S, and thiophenol could be discriminatively detected in solution and in living cells.