Selective detection of cysteine over homocysteine and glutathione by a bis(bromoacetyl)fluorescein probe

Abstract A bromoacetyl functionalized fluorescein chemodosimeter ( 1 ) was utilized as a fluorescent probe for cysteine. The probe showed a selective and sensitive response to cysteine over homocysteine and glutathione in aqueous buffer through a rapid cyclization reaction. When cysteine was added, a fast fluorescence turn-on change of 1 was observed, thus allowing cysteine to be discriminated from other biothiols and micromolar concentrations of cysteine to be detected by the naked eye.