Fluorescence method for monoamine oxidase B detection based on the cage function of glyoxal and phenethylamine on G-rich DNA

Abstract

Monoamine oxidase B (MAO-B) is an important biomarker of neurodegenerative disease. For early and accurate diagnosis of neurodegenerative disease, constructing sensitive and convenient biosensors for detecting MAO-B have gained vast attention recently. Herein, we reported a simple fluorescence assay to detect MAO-B based on the cage function of glyoxal and phenethylamine (PEA) on guanine (G)-rich DNA. G-quadruplex, a four-stranded structure, can light up the fluorescence emission of thioflavin T (ThT) with high efficiency. As a bridge, glyoxal introduces the benzene ring of PEA into the G-rich DNA sequences, leading to the destroyed G-quadruplex and the reduced fluorescence intensity of G-quadruplex/ThT. In the presence of target MAO-B, PEA was oxidized into phenylacetaldehyde, resulting in an increase amount of G-quadruplex structure. With the increase amount of MAO-B, the fluorescence response of G-quadruplex/ThT increased. Under the optimum conditions, this method has a wide linear range from 0.5 to 10 μg/mL, with a detection limit of 0.02 μg/mL. It provides a straightforward strategy for the early diagnosis of neurodegenerative disease.