Electrochemical Detection of 6-Thioguanine and DNA Hybridization with Oligonucleotide Biosensors by Differential Pulse Voltammetry (DPV)

Abstract

The development of a simple and inexpensive DNA biosensor based on a gold nanoparticle (Au-NPs)/glutathione (GSH) matrix is reported to characterize DNA hybridization. The adhesion and morphological properties of the film were characterized using contact angle measurements and scanning electronic microscopy (SEM), respectively. The modified gold electrode was characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The results indicate that DNA/AuNPs-GSH/cysteine provides excellent sensitivity for the target DNA in the linear range of response from 7 pM to 5 nM. The interaction of 6-thioguanine (6-tg) with the double stranded DNA (ds-DNA) and single stranded DNA (ss-DNA) modified electrode was investigated using DPV and EIS. Consequently, 6-tg is accumulated onto the modified electrode causing a decrease of the charge transfer resistance (R_ct) across the dynamic range from 1 pM to 10 µM. The developed electrochemical DNA biosensor was demonstrated to be efficient to characterize the interactions with drugs and micropollutants in wastewater.

Keywords:

• DNA Biosensor
• DNA hybridization
• differential pulse voltammetry (DPV)
• electrochemical impedance spectroscopy (EIS)
• 6-thioguanine (6-tg)

Acknowledgement

The authors would like to thank “Ministère Tunisien de l’Enseignement Supérieur” for support.

Disclosure statement

No potential conflict of interest was reported by the authors.