Highly sensitive electrochemical impedance sensing of PEP gene based on integrated Au-Pt alloy nanoparticles and polytyramine

Fabrication of an electrochemical impedimetric DNA biosensor based on the integration of Au-Pt alloy nanoparticles (Au-Pt-NPs) and electropolymerized polytyramine (Pty) film for the detection of phosphoenolpyruvate carboxylase (PEP) gene is described in this article, where Pty films acted as an ideal combination platform for Au-Pt-NPs via electrostatic adsorption. The electrochemical properties of the Au-Pt-NPs/Pty, the characteristics of the immobilization and hybridization of DNA were investigated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy (EIS), respectively. Primary study indicated that Au-Pt-NPs/Pty had a synergistic effect on the electrochemical signal of [Fe(CN)(6)](3-/4-), which served as the classic redox probe in the most electrochemical impedimetric sensors. DNA sequence-specific of PEP transgene existed in some transgenic crops was detected by this EIS protocol. The dynamic detection range of this DNA electrochemical biosensor to the DNA target sequence was from 1.0 x 10(-12) M to 1.0 x 10(-7) M. The detection limit was measured to be 3.6 x 10(-13) M. The DNA biosensor also had good selectivity, stability and reproducibility. (C) 2012 Elsevier B.V. All rights reserved.