An Nb-doped Nickel Oxide-Carbon Nanotubes Composite- Enhanced Electrochemical DNA Biosensor for Detection of Lead(II) Ion

A novel niobium doped nickel oxide nanoparticle (NbNiO) was synthesized by sol-gel method and was applied to fabricate DNA biosensor for detection of Pb 2+ in water sample for the first time. The amino-modified G-rich DNA probes were immobilized on the surface of CH-NbNiO-MWCNTs/ITO electrode by the covalent interaction between the amino of DNA and the carboxyl of MWCNTs. When the lead (II) ion (Pb 2+ ) interacted with the G-rich DNA, it will induce the DNA conformational to switch from a random-coil to a G-quadruplex resulting in an increase of alternating current impedance. On the basis of this, we developed an impedance biosensor for the detection of Pb 2+ . The results showed that the synergistic effect of the synthesized NbNiO nanoparticles and MWCNs could improve the performance of this DNA biosensor. Under optimal conditions, the fabricated DNA biosensor possess a wide linear range of 1.0×10 -10 to 1.0×10 -5 M (correlation coefficient, R=0.998) and a low detection limit of 7.51 ×10 -12 M (3σ).