Impedimetric detection of influenza A (H1N1) DNA sequence using carbon nanotubes platform and gold nanoparticles amplification

In this work we report the use of an impedimetric genosensor for the model detection of H1N1 swine flu correlated DNA sequence. An oligonucleotide DNA probe, complementary to the target H1N1 virus sequence, was immobilized onto the electrode surface by covalent binding. Two different protocols, i.e. direct hybridization with the DNA target and a sandwich scheme, were employed and compared. In both cases the resulting hybrid was biotin-labelled to allow the additional conjugation with streptavidin gold nanoparticles (strept-AuNPs). The latter were used with the aim of enhancing the impedimetric signal, thus improving the sensitivity of the technique. The best limit of detection, obtained with the sandwich scheme after signal amplification step was 7.5 fmol (corresponding to 577 pmol L-1). Furthermore, a gold enhancement treatment was performed in order to compare the presence and distribution of gold nanoparticles onto the electrode surface. As an alternative way of visualization, streptavidin conjugate quantum dots (strept-QD) were employed to obtain fluorescence images of the DNA-biotin-strept-QD electrode surface. Finally, a comparison between impedance and microscopy was performed in terms of viability and feasibility of the techniques. © 2010 The Royal Society of Chemistry.