Electrical detection of deoxyribonucleic acid hybridization based on carbon-nanotubes/nano zirconium dioxide/chitosan-modified electrodes

A novel and sensitive electrochemical DNA biosensor based on nanoparticles ZrO2 and multi-walled carbon nanotubes (MWNTs) for DNA immobilization and enhanced hybridization detection is described. The MWNTs/nano ZrO2/chitosan-modified glassy carbon electrode (GCE) was fabricated and oligonucleotides were immobilized to the GCE. The hybridization reaction on the electrode was monitored by differential pulse voltammetry (DPV) analysis using electroactive daunomycin as an indicator. Compared with previous DNA sensors with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics increased DNA attachment quantity and complementary DNA detection sensitivity. The response signal increases linearly with the increase of the logarithm of the target DNA concentration in the range of 1.49 x 10-10 to 9.32 x 10-8 mol L-1 with the detection limit of 7.5 x 10-11 mol L-1 (S/N = 3). The linear regression equation is I = 32.62 + 3.037 log C DNA (mol L-1) with a correlation coefficient value of 0.9842. This is the first application of carbon nanotubes combined with nano ZrO2 to the fabrication of an electrochemical DNA biosensor with a favorable performance for the rapid detection of specific hybridization