Construction of manganese oxide nanowire-like cluster arrays on a DNA template: Application to detection of hydrogen peroxide.

Improved electron transfer properties and catalytic activity of manganese oxide (MnOx) was demonstrated following its electrochemical deposition on a deoxyribonucleic acid (DNA) modified glassy carbon electrode. The MnOx showed different morphologies, electrocatalytic properties and electrochemical kinetics. Scanning electron microscopy showed that electrodeposition of MnOx on a bare glassy carbon electrode led to the formation of irregular-shapes while a nanowire cluster (NWC) was formed on a GCE/DNA due to the DNA serving as a template. Electrochemical impedance spectroscopy (EIS) revealed lower charge transfer resistance of the MnOxNWC compared with MnOx. A new mechanism is presented for the electrodeposition of MnOx on the surface of a GC/DNA electrode. An electrochemical biosensor was fabricated based on depositing MnOx onto a glassy carbon /DNA electrode (GCE/DNA/MnOxNWC) and was used to detect hydrogen peroxide (H2O2). The MnOx nanowire cluster and DNA exhibited significant electrocatalytic activity for simultaneous electrocatalytic oxidation at two oxidation potentials (0.6 V and 0.98 V vs Ag/AgCl) and one reduction potential (-0.5 V vs Ag/AgCl) for H2O2 at pH 6.0. A new mechanism for the detection of H2O2 is presented. Excellent electrocatalytic activity, stability and facility for simultaneous detection of H2O2 at different of applied potentials are proposed advantages of the proposed electrochemical biosensor.