Electrochemical sensor based on MoS2 nanosheets and DNA hybridization for trace mercury detection

Abstract

• Chitosan/GO/MoS 2 /AuNPs and T-Hg 2+ -T base pair were used to form an electrochemical sensor with low detection limit, good repeatability, and specificity. • MoS 2 nanosheets were used as a substrate for the immobilization of DNA and amplified the electrochemical signal produced by the sensor. • A novel electrochemical method for trace Hg 2+ detection in water was developed. Mercury ions (Hg 2+ ) are highly toxic and can cause serious harm to the environment and human health. In this study, we prepared a novel electrochemical sensor based on an electrode coated with chitosan/graphene oxide/molybdenum disulfide/Au nanoparticles (chitosan/GO/MoS 2 /AuNPs) and thymine-Hg 2+ -thymine base pair to detect trace Hg 2+ in water. This method effectively utilized the affinity of MoS 2 to immobilize deoxyribonucleic acid (DNA) on the electrode surface and enabled the amplification of the electrochemical signals detected by the sensor. The specific binding of the thymine-Hg 2+ -thymine base pair and the electrochemical activity of MoS 2 successfully reduced the detection limit of Hg 2+ and rendered it interference resistant. In the presence of Hg 2+ , a double-stranded structure was formed on the electrode after the interaction between Hg 2+ and DNA, which caused the change of the oxidation current signal of the electrode surface. The sensor showed good linearity ranging from 0.01 μg/L to 4 μg/L with a correlation coefficient of 0.991, and the limit of detection was found to be 5.8 ng/L. This portable chitosan/GO/MoS 2 /AuNPs modified electrode showed satisfactory recovery in tap water samples, thus demonstrating its potential for application in trace Hg 2+ detection.