Electrochemical Detection of Ultratrace Lead Ion through Attaching and Detaching DNA Aptamer from Electrochemically Reduced Graphene Oxide Electrode

• Main Authors: Su Hwan Yu, Chang-Seuk Lee, Tae Hyun Kim
• Format: Article
• Language: English
• Published: MDPI AG 2019-05-01
• Series: Nanomaterials
• Subjects: reduced graphene oxide; G-quadruplex; lead ion; electrochemical aptasensor
• Online Access: https://www.mdpi.com/2079-4991/9/6/817
• ISSN: 2079-4991

This paper describes a simple strategy for the ultratrace level detection of Pb²⁺ ion based on G-quadruplex DNA and an electrochemically reduced graphene oxide (ERGO) electrode. First, ERGO was formed on a glassy carbon electrode (GCE) by the reduction of graphene oxide (GO) using cyclic voltammetry. Subsequently, a methylene blue (MB)-tagged, guanine-rich DNA aptamer (Apt) was attached to the surface of ERGO via π-π interaction, leading to the Apt-modified ERGO electrode. The presence of Pb²⁺ could generate the folding of Apt to a G-quadruplex structure. The formation of G-quadruplex resulted in detaching the Apt from the ERGO/GCE, leading to a change in redox current of the MB tag. Electrochemical measurements showed the proposed sensor had an exceptional sensitivity for Pb²⁺ with a linear range from 10^−15 to 10^−9 M and a detection limit of 0.51 fM. The sensor also exhibited high selectivity for Pb²⁺, as well as many other advantages, such as stability, reproducibility, regeneration, as well as simple fabrication and operation processes.