Signal amplification for electrochemical DNA biosensor based on two-dimensional graphene analogue tungsten sulfide-graphene composites and gold nanoparticles

A novel two-dimensional graphene analogue tungsten sulfide-graphene (WS2-Gr) composite was synthesized to achieve excellent electrochemical properties for applications as DNA biosensor. Gr served as a 2D conductive skeleton that supported a highly electrolytic accessible surface area of WS2 nanocomposite which was prepared by a hydrothermal method. A sensitive electrochemical DNA biosensor was fabricated by using the WS2-Gr-chitosan composites modified glassy carbon electrode to anchor Au nanoparticles (AuNPs), which subsequently used to capture ssDNA sequences. Cyclic voltammetry and electrochemical impedance spectroscopy were carried out for the characterization of modified electrodes. Under optimum conditions, the developed biosensor showed a good linear relationship between the current value and logarithm of the target DNA concentration ranging from 0.01 to 500 pM with a detection limit of 0.0023 pM. The DNA biosensor exhibited excellent discrimination ability to detect one-base mismatched DNA, three-base mismatched DNA and non-complementary DNA sequence. This work described a simple strategy for the preparation of a stable and conductive interface for electrochemical detection of DNA hybridization and opened a path for the application of WS2-Gr nanocomposite in DNA electrochemical biosensing analysis. (C) 2013 Elsevier B.V. All rights reserved.