A novel fluorescence aptasensor for 8-hydroxy-2'-deoxyguanosine based on the conformational switching of K(+)-stabilized G-quadruplex

Abstract

A sensitive, lable-free and low cost fluorescence aptasensor was developed for detecting 8-hydroxy-2'-deoxyguanosine (8-OHdG) by using 8-OHdG aptamer (Apt) as a recognition probe and N-methyl mesoporphyrin IX (NMM) as a reporter. The method is based on the conformational switching of a K(+)-stabilized G-quadruplex to a 8-OHdG-stabilized one. NMM can selectively bind to K(+)-stabilized G-quadruplex instead of 8-OHdG-stabilized one. The addition of 8-OHdG in the solution of Apt - K(+) ions leads to a sharp change in fluorescence intensity, which showed a good linear response toward 8-OHdG concentration ranging from 3.96 nM to 211 nM with a detection limit of 1.19 nM. The relative standard deviation and the recovery were 1.23-3.26% (n=11) and 94.8-106.7%, respectively. The proposed aptasensor consists of only an aptamer probe and a specific dye NMM, avoiding the complex and expensive labeling procedure. Thus it is much cheaper and more applicable.

Keywords: 8-Hydroxy-2′-deoxyguanosine; Conformational switching; Fluorescence aptasensor; K(+)-stabilized G-quadruplex; N-methyl mesoporphyrin IX.