Design and synthesis of a novel "turn-on" long range measuring fluorescent probe for monitoring endogenous cysteine in living cells and Caenorhabditis elegans.

Cysteine (Cys) is an indispensable small organic molecule containing sulfhydryl groups, which has essential regulatory effects on the physiological process of human body. In this work, a red emission fluorescent probe TCFQ-Cys was designed and exploited based on 2-(3-cyano-4,5,5-trimethylfuran-2(5 H)-ylidene) malononitrile-derivatives. The probe could effectively monitor Cys through the typical acrylate cleavage. The detecting system showed a red emission at 633 nm and the fluorescence was stable within the pH range of 6–9. The detection could be completed in 30 min. TCFQ-Cys presented high sensitivity with a detection limit of 0.133 μM and high selectivity towards Cys from other biological mercaptans. The most important feature was that the system had a wide linear range of 0–300 μM, which covered the physiological requirements of Cys detection. Subsequently, we conducted the biological imaging of Cys in MCF-7 cells and Caenorhabditis elegans (C. elegans). Therefore, TCFQ-Cys had a practical application prospect for further investigating the physiological function of Cys. A red emission fluorescent probe TCFQ-Cys was develop to monitor the Cys level through the typical acrylate cleavage. The detecting system showed a red emission at 633 nm and the fluorescence was stable within the pH range of 6–9. The detection could be complete in 30 min. TCFQ-Cys presented high sensitivity with a detection limit of 0.133 μM and high selectivity towards Cys than other biological mercaptans. The most important feature was that the system had a wide linear range of 0–300 μM, which covered the physiological requirements of Cys detection. Subsequently, we conducted the biological imaging of Cys in MCF-7 cells and Caenorhabditis elegans (C. elegans). Therefore, TCFQ-Cys had a practical application prospect in further investigating the physiological function of Cys. Image 1 • A red emission fluorescent probe for real-time detection of cysteine. • The probe could semiquantitatively determine the cysteine level in living cells. • The probe could image endogenous cysteine in situ in Caenorhabditis elegans. • Exhibiting wide linear range, long wavelength emission and low detection limit. [ABSTRACT FROM AUTHOR]