A label-free electrochemical aptasensor based on graphene oxide/double-stranded DNA nanocomposite

A novel label-free electrochemical impedance aptasensor based on a gold nanoparticles/double-stranded DNA-graphene (AuNPs/dsDNA-GO) nanocomposite modified glassy carbon electrode was presented for quantitative determination of thrombin. GO was covalently functionalized with dsDNA via a facile amidation process, and then AuNPs were electrodeposited onto the surface of dsDNA-GO. The morphology, conductivity and interaction of the as-prepared nanocomposites were characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), Raman and Fourier transform infrared spectroscopy. The thrombin-binding aptamer(TBA)was conjugated to AuNPs via goldthiol chemistry to construct electrochemical aptasensing platform, and the specific recognition between TBA and thrombin was monitored by EIS. Under optimum conditions, thrombin could be quantified in a wide range of 0.1-100 nM (R-2 = 0.9960) with low detection limit of 0.06 nM (S/N =3). (C) 2016 Elsevier B.V. All rights reserved.