A polypyrrole cDNA electrode for the amperometric detection of the West Nile Virus

The determination of a short cDNA sequence from West Nile Virus (WNV) was carried out with an amperometric DNA sensor. The latter was constituted by an amino-21-mer oligonucleotide probe covalently anchored to a poly(pyrrole-NHS), previously electro-polymerized on a platinum electrode. After incubation with a target model of the WNV cDNA, the hybridization events on the sensor surface were detected by an additional hybridization process with a complementary biotinylated 15-mer WNV cDNA followed by the specific attachment of a biotinylated glucose oxidase via an avidin bridge. The hybridization event was then monitored at 0.6 V vs Ag/AgCl by amperometric detection of H2O2, generated by the enzyme marker in the presence of glucose. A relatively short (2 h) hybridization period allows the convenient quantification of the WNV DNA target in the range 10−10–10−15 g ml−1.