A turn-on fluorescent probe for simultaneous sensing of cysteine/homocysteine and hydrogen sulfide and its bioimaging applications.

Hydrogen sulfide and biothiol molecules such as Cys, Hcy, and GSH play important roles in biological systems. Exploiting a probe to simultaneously detect and distinguish them is quite important. In this work, a versatile fluorescent probe that can simultaneously detect and discriminate Cys/Hcy and H2S is reported. The probe easily prepared by the Knoevenagel condensation of cyanoacetylindole with chlorinated phenyl-propenal possessed three potential sites that could react with biothiols and H2S. This probe also exhibited rapidity, high selectivity, and sensitivity for Cys/Hcy and H2S with distinct optical signal changes. The probe was able to display obvious fluorescence enhancement at 480 nm for Cys/Hcy and unique absorbance enhancement at 500 nm for H2S. We also demonstrated that the probe can be successfully applied to image Cys in MCF-7 cells suing a confocal fluorescence microscope.