Monoaromatic Fluorescence Probe for Sensitive Alkaline Phosphatase Analysis by Regulating Intramolecular Hydrogen Bonding

Abstract

Enzymatic reactions have been widely applied to the design of various sensing systems. However, the detection sensitivity of partial systems is still low, possibly attributed to the large molecular size of the substrate. In this study, we propose a strategy toward sensitive enzyme analysis with monoaromatic substrate. That is, salicyl phosphate ester (SPE) as a fluorimetric probe is presented for evaluating the enzymatic activity of alkaline phosphatase (ALP). The sensing mechanism is that ALP catalyzes the dephosphorylation cleavage of SPE and generates salicylic acid with strong fluorescence by modulating intramolecular hydrogen bonding. Due to the specific phosphorylation-dephosphorylation chemistry, the SPE based probe shows high specificity toward ALP over other possible interferents. The SPE probe provides a limit of detection of 0.005 U L-1 .In addition, the practical application of the SPE probe is supported by ALP determination in human serum.