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

• A fluorescence aptasensor for 8-OHdG was developed using Apt-K+-NMM system.
• The strategy can detect 8-OHdG at concentration as low as 1.19 nM.
• The aptasensor consists of only an aptamer and a specific dye NMM.
• The binding mechanism of 8-OHdG to K+-stabilized G-quadruplex was verified.

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.

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