A sequence-specific DNA electrochemical sensor based on acetylene black incorporated two-dimensional CuS nanosheets and gold nanoparticles

Recently, two-dimensional transition-metal chalcogenides attract increasing interest because of their remarkable structural and electronic properties. In this work, acetylene black (AB) incorporated CuS nanosheets are synthesized via a simple solvothermal route assisted by ethylene glycol. The obtained sample is characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectra. A novel DNA electrochemical biosensor is fabricated with the DNA labeled at 5′ end using 6-mercapto-1-hexhane immobilized on the CuS-AB/Au nanoparticles modified electrode through Au-S interaction. After blocked with 6-mercapto-1-hexanol, the probe DNA is bound with the addition of target DNA to form the double-stranded structure on the electrode surface, which leads to a significantly decrease of peak current of electrochemical indicator [Fe(CN)6]3−/4−. Under optimum conditions, the amperometric signals decrease linearly with the target DNA concentrations (0.1 pM-1 nM), and the DNA sensor exhibits a detection limit as low as 20 fM (3σ/S) with an excellent differentiation ability. The proposed method also shows acceptable stability and reproducibility. The good analytical performance can be attributed to the synergistic effect of acetylene black and the unique microstructure of CuS nanosheets. This can open up new opportunities for sensitive and selective detection of specific sequence DNA and provide a promising platform for sensor or biosensor designs for other biomoleculars detection.