Label-free electrochemical detection of Avian Influenza Virus genotype utilizing multi-walled carbon nanotubes-cobalt phthalocyanine-PAMAM nanocomposite modified glassy carbon electrode

A novel DNA electrochemical biosensor for label-free determination of DNA sequence related to the Avian Influenza Virus (AIV) genotype was demonstrated in this paper. First, the multi-walled carbon nanotubes-cobalt phthalocyanine (MWNTs-CoPc) nanocomposite and poly (amidoamine) (PAMAM) dendrimer (generation 4.0) were modified on the glassy carbon electrode (GCE) sequentially. Then, DNA probes were successfully immobilized on the modified electrode with G4 PAMAM dendrimer acting as the coupling agent. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement based on the oxidation signals of guanine without any external labels. Under the optimal conditions, the difference in guanine oxidation signal of the probe modified GCE in the absence and presence of complementary target (Delta I-p) was linear with the logarithmic value of the complementary target concentration from 0.01 to 500 mg/ml with a correlation coefficient of 0.998 and a detection limit of 1.0 pg/ml. (C) 2009 Elsevier B.V. All rights reserved.