A novel probe for colorimetric and near-infrared fluorescence detection of cysteine in aqueous solution, cells and zebrafish.

Cysteine(Cys) is tightly related to physiological and pathological of human, and the imbalance of concentration of cysteine in the intracellular are associated with many diseases. Here, a novel NIR fluorescent probe TCF-Cys was designed and synthesized, and both the optimal excitation and emission wavelength of them were between 650 and 900 nm, that within the "optical window" of biological tissues. In aqueous solution, TCF-Cys, which with an acrylate extremity as a recognizing unit, exhibited excellent "turn-on" fluorescence response for Cys superior to other amino acids and thiols with a limit of detection of 0.1323 μM. Moreover, as an excellent naked-eye colorimetric indicator, TCF-Cys could effectively distinguishing the Cys, Hcy and GSH in aqueous solution through color change. Then, the response mechanism of TCF-Cys for Cys was revealed by TLC, ¹ H NMR, HPLC, HRMS and DFT calculation. Finally, TCF-Cys was successfully employed to fluorescence specifically map of exogenous and endogenous Cys in living cells and zebrafish with low toxicity.
(Copyright © 2019 Elsevier B.V. All rights reserved.)