A Highly Sensitive Electrochemical DNA Sensor Based on Nanostructured Electrode of Multi-Walled Carbon Nanotubes/Manganese Dioxide Nano-Flowers-like/Polyaniline Nanowires Nanocomposite

Abstract

We report here a development of a novel and label-free electrochemical DNA sensor based on a nanostructured electrode of multi-walled carbon nanotubes/manganese dioxide nano-flowers-like/polyaniline nanowires (MWCNTs/MnO2/PANi NWs) nanocomposite. The nanocomposite was synthesized in situ onto the interdigitated platinum microelectrode (Pt) using a novel combined chemical-electrochemical synthesis method: chemical preparation of MWCNTs/MnO2 and electropolymerization of PANi NWs. The fabricated MWCNTs/MnO2/PANi NWs was used for the first time to develop a label-free electrochemical DNA sensor for detection of a specific gene of Escherichia coli (E. coli) O157:H7. The Pt electrode surface modification by the MWCNTs/MnO2/PANi NWs can facilitate the immobilization of probe DNA strands and therefore the electrochemical signal of the DNA sensors has been improved. The electrochemical impedance spectroscopy (EIS) measurements were conducted to investigate the output signals generated by the specific binding of probe and target DNA sequences. The developed electrochemical biosensor can detect the target DNA in the linear range of 5 pM to 500 nM with a low limit of detection (LOD) of 4.42 × 10–13 M. The research results demonstrated that the MWCNTs/MnO2/PANi NWs nanocomposite-based electrochemical DNA sensor has a great potential application to the development of highly sensitive and selective electrochemical DNA sensors to detect pathogenic agents.