Highly fluorescent and specific molecular probing of (homo)cysteine or superoxide: biothiol detection confirmed in living neuronal cells.

Chemodosimetric action in detection of cysteine and homocysteine (310- and 290-fold) and superoxide inputs (336-fold increase) gives significant fluorescence intensity increases. Detection limits of 2.13 × 10(-5) M, 1.37 × 10(-5) M, and 2.71 × 10(-5) M, respectively, are biorelevant and are consistent with "OR" logic gating, demonstrated in intracellular biothiol detection in neuronal cells by way of novel fluorescein derivatization. As per our knowledge, this is the first example of a novel fluorescent probe based on the nucleophilic substitution reaction of biothiols and superoxide through ester cleavage.