Development of a NIR fluorescent probe for detection of cysteine and its application in bioimaging

In this work, A new near-infrared (NIR) fluorescent probe NIR-L based on dicyanoisophorone was rationally designed, synthesized and characterized for the detection of cysteine (Cys). This probe exhibited highly selective and sensitive response to Cys over other analytes including amino acids, cations and anions under physiological conditions, which can be identified by naked eyes. It was found that the probe showed NIR fluorescence turn-on response at 714 nm toward Cys with a large Stokes shift of 174 nm and a very low detection limit of 28.6 nM. The results of 1H NMR and DFT calculation further confirmed that the addition of Cys triggered a reaction between Cys and NIR-L, leading to the release of a NIR fluorescent dye NIR-OH. Moreover, NIR-L was successfully used to realize the in vivo Cys bioimaging in HeLa cells and mice. Significantly, the sensing system was applied in imaging of Cys in B16-F10 tumor-bearing mice.