Sensitive PAT gene sequence detection by nano-SiO2/p-aminothiophenol self-assembled films DNA electrochemical biosensor based on impedance measurement

Nano-SiO2/p-aminothiophenol (PATP) film was fabricated by self-assembly and electrodeposition methods. The immobilization and hybridization of DNA on the nano-SiO2/PATP film were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS was applied to label-free detection of the target DNA according to the increase of the electron transfer resistance (R,,) of the electrode surface after the hybridization of the probe DNA with the target DNA. This DNA electrochemical biosensor showed its own performance of simplicity, good stability, fine selectivity and high sensitivity, and was successfully applied to the detection of the PAT gene sequences by a label-free EIS method. The dynamic detection range was from 1.0 X 10(-11) to 1.0 X 10(-6) mol/L 20-base sequence of the PAT gene, with the detection limit of 1.5 x 10(-12) mol/L. This DNA sensor has a good ability of recognizing single- or double-base mismatched DNA sequence with the complementary DNA sequence. (c) 2007 Elsevier B.V. All rights reserved.