Chemiresistive biosensors based on carbon nanotubes for label-free detection of DNA sequences derived from avian influenza virus H5N1

We developed chemiresistor-type biosensors based on carbon nanotubes for highly efficient and fast detection of avian influenza virus (AIV) subtype H5N1 DNA sequences. Semiconducting single-walled carbon nanotubes (sc-SWCNTs) or nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) were used as two alternative active sensing elements, and their sensitivity to different concentrations of DNA target were compared. In these sensors long nanotubes (>5 μm) were placed between interdigitated metal electrodes so that individual nanotubes connect the electrodes. The nanotubes were functionalized with DNA probe sequences non-covalently attached to the sidewalls. Such functionalized-nanotube sensors could reliably detect complementary DNA target sequences of the AIV H5N1 with concentration ranging from 2 pM to 2 nM in 15 min and at room temperature. Our nanotube-based biosensors are small, flexible, disposable and easy-to-fabricate that makes them promising for point-of-care applications and clinical diagnostics.