Highly Sensitive Electrochemical Determination of Lead(II) by Double Stranded DNA (dsDNA) with a Carbon Paper/Reduced Graphene Oxide (CP/rGO) Substrate by Differential Pulse Anodic Stripping Voltammetry (DPASV)

Abstract

Lead pollution may cause serious damage to environment safety and human health, especially to children’s growth. In this work, by using double stranded DNA (dsDNA) as the recognition element, a simple and effective electrochemical DNA sensor has been developed on a full carbon-based substrate, reduced graphene oxide/carbon paper (rGO/CP), to accomplish the rapid, sensitive and selective determination of Pb²⁺. Carbon paper (CP) provides a suitable substrate for the sensor with high portability and low cost, while rGO is easily electrodeposited onto CP and serves as both the signal amplification element and the molecular bridge between DNA and CP. Because of its high specific surface area and unique conjugated giant π structure, rGO tightly binds with DNA through π-π stacking and hydrophobic interactions, thereby providing loading of high quantities of DNA. The specific coordination between DNA and Pb²⁺ further improves the sensitivity of the sensor. The results demonstrate that rapid electrochemical enrichment of Pb²⁺ is achieved using the constructed CP/rGO/DNA electrode with a linear relationship between the peak current and the concentration of Pb²⁺ from 1 pM to 100 pM and a detection limit of 1 pM. In addition, this approach shows good selectivity and satisfactory repeatability for river water analysis. A promising sensitive, low-cost, simply-fabricated, and portable full carbon-based electrochemical biosensing platform has been therefore provided for lead determination.