The study on biosensors for Hg2+ based on Au-MoS2 nanocomposites

• 1、College of Environmental and Energineering, Beijing University of Technology, Beijing, 100124

Abstract：Thymine (T) rich DNA was used to fabricate a novel electrochemical DNA sensors for Hg2+ based on the high specificity of T-Hg2+-T combination and the amplification of current signal of voltammetric peak by horseradish peroxidase (HRP) and MoS2 nanosheets. Au-MoS2 nanocomposites were prepared. The composites were modified onto a glassy carbon electrode (GCE) and thiol-modified DNA probe 1 (DNA1) was also immobilized the GCE based on the chemisorption of thiols on the surface of AuNPs. Thiol-modified DNA probe 2 (DNA2), AuNPs and HRP were used to prepare HRP-Au-DNA2 composites. The specific mismatch of Hg2+ ions with thymines of the two probes of T-rich single-stranded DNA to produce double strand DNA (dsDNA) was used to immobilize HRP onto the GCE surface. The peak current of square wave voltammetry (SWV) produced by the redox reaction between hydroquinone (HQ) and hydrogen peroxide (H2O2) catalyzed by the immobilizing HRP and MoS2 nanosheets was used as signal of detecting Hg2+. The results showed that under the optimal experimental conditions the peak current of SWV increased linearly with the increase of the logarithmic values of Hg2+ concentration over the range of 1.0 nmol/L to 1.0 μmol/L Hg2+ with a detection limit of 0.1 nmol/L. The stability and selectivity of the sensor were also investigated. The sensor was applied in the determination of Hg2+in real water samples and satisfactory results were obtained.

Keywords： mercury ions horseradish peroxidase molybdenum disulfide DNA biosensors