Enhanced sensitivity for deoxyribonucleic acid electrochemical impedance sensor: gold nanoparticle/polyaniline nanotube membranes.

Gold nanoparticle/polyaniline nanotube membranes on the glassy carbon electrode (Au/nanoPAN/GCE) were constructed for the electrochemical sensing of the immobilization and hybridization of DNA. The properties of the Au/nanoPAN/GCE, the characteristics of the immobilization and hybridization of DNA were studied by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. The synergistic effect of the two kinds of nanomaterials, nanogold and nanoPAN, could enhance dramatically the sensitivity for the DNA hybridization recognition. DNA sequence-specific of phosphinothricin acetyltransferase gene (PAT) existing in some transgenic crops was detected by electrochemical impedance spectroscopic measurement. The dynamic detection range of the sequence-specific DNA was from 1.0x10(-12) to 1.0x10(-6) mol L(-1), and the detection limit was 3.1x10(-13) mol L(-1). This biosensor had much wider dynamic detection range and lower detection limit for the DNA detection as compared with other DNA biosensors reported by us. The biosensor also has good selectivity, stability and reproducibility.