Electrochemical DNA Biosensors Based on Gold Nanoparticles / Cysteamine / Poly(glutamic acid) Modified Electrode

In the present study, an electrochemical DNA sensing strategy for highly sensitivity detection of DNA hybridization was reported based on a gold nanoparticles (AuNPs) / cysteamine (Cys) / poly glutamic acid (PGA) modified electrode. A glassy electrode was first modified with the polymer film by cyclic voltammetry (CV), and then AuNPs were immobilized on the surface of PGA with Cys as a linker, to which probe DNA was covalently linked onto the surface of AuNPs through a 5′-thiol-linker. The DNA hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated adriamycin. Under optimal conditions, the reduction peak currents were linearly increased with increasing the concentration of complementary target DNA from 9.0×10 -11 to 4.8×10 −9 M with a detection limit of 4.2×10 -11 M. This DNA biosensor exhibited excellent selectivity, reproducibility and stability in DNA hybridization assay.