Sensitive Detection of Butyrylcholinesterase Activity Based on a Stimuli-Responsive Fluorescence Reaction

A fluorogenic reaction between the chelate of Mn(II)-citric acid and terephthalic acid (PTA) was discovered, which was carried out through heating the aqueous mixture of Mn2+, citric acid and PTA. Detailed investigations indicated the reaction products were 2-hydroxyterephthalic acid (PTA-OH), which was attributed to the reaction between PTA and & BULL;OH, formed by the triggering of Mn(II)-citric acid in the presence of dissolved O2. PTA-OH showed a strong blue fluorescence, peaked at 420 nm, and the fluorescence intensity presented a sensitive response to pH of the reaction system. Based on these mechanisms, the fluorogenic reaction was used for the detection of butyrylcholinesterase activity, achieving a detection limit of 0.15 U/L. The detection strategy was successfully applied in human serum samples, and it was also extended for the detection of organophosphorus pesticides and radical scavengers. Such a facile fluorogenic reaction and its stimuli-responsive properties offered an effective tool for designing detection pathways in the fields of clinical diagnosis, environmental monitoring and bioimaging.