The Two‐Steps Reaction Fluorescent Probe for the Selective Detection of Cysteine and Its Applications**

Abstract

We reported the specific fluorescent probe (MC‐BOD‐XDS) with two‐steps reaction based on monosulfanyl‐coumarin‐BODIPY for selective detection of cysteine, high activity sulfanyl‐coumarin as the multiple reaction group instead of a group internal standard fluorophore. The reaction mechanism of MC‐BOD‐XDS for detecting cysteine was different from the reported probes about the nucleophilic aromatic substitution reaction (SNAr) of chlorinated BODIPY. The fluorescent color of MC‐BOD‐XDS changed from yellow to red, and then to orange. The linear calibration diagram showed that it can potentially be used for quantitatively detection of Cys. Its potential applications were demonstrated by employing it for detection of Cys in artificial urine and in fluorescent imaging in HeLa cells.

Insight on Mercapto-Coumarins: Synthesis and Reactivity

“…A specific fluorescent probe based on monosulfanyl-coumarin-BODIPY for the selective detection of cysteine in living cells and artificial urine has been synthesized via a simple substitution reaction on the 5-position of XDS-BOD-XDS:BODIPY-Cl 2 ( 68 ) with the thiol group generated from 7-mercapto-4-methyl coumarin ( 50 ) to yield MC-BOD-XDS ( 69 ), XDS-BOD-XDS ( 70 ) ( Scheme 23 ) [ 75 ]. The reactivity could be attributed to the free SH-coumarin, which quickly binds to another MC-BOD-XDS and produces strong red fluorescent XDS-BOD-XDS ( 70 ) [ 75 ].…”