Rapid detection of trace Hg~(2+) in animal matrix by specific DNA electrochemical sensor

Abstract

A highly specific electrochemical biosensor based on T-Hg~(2+)-T structure for fast screening trace Hg~(2+) in complex animal drug matrix was constructed by cyclic voltammetry(CV) and differential pulse voltammetry(DPV). In the presence of Hg~(2+), it can be specifically binded to the T base of DNA sequence on the surface of modified gold electrode, which changes the conformation of DNA molecule and the electrochemical signal. The concentration ratio of EDC/NHS, the concentration ratio of FC-DNA and the reaction time of the biosensor were optimized by the index of sensitivity and reproducibility in CV. The results showed that the stability of the biosensor was good within 3 days(RSD≤1.3%), the difference between batches was low(RSD=4.7%), and the specificity of the biosensor was high in the presence of interfering ions(As~(3+), Cd~(2+), Cu~(2+), Pb~(2+), Zn~(2+) and Fe~(3+)). DPV results showed that the peak current signal value has a linear relationship with the lgC_((Hg)) over a concentration range from 0.1 nmol·L~(-1) to 1.0 μmol·L~(-1) with a detection limit of 0.066 nmol·L~(-1). Finally, the recovery rate tested in the matrix of animal medicine was satisfactory as 99.17%-101.3%, which can meet the needs of the determination of trace Hg~(2+) in the matrix of Bombyx Batryticatus, and provide a new idea for the rapid screening of trace heavy metals in the matrix of other types of complex traditional Chinese medicine.