Electrochemical detection of hepatitis B and papilloma virus DNAs using SWCNT array coated with gold nanoparticles.

This study investigated electrochemical detection of human hepatitis B and papilloma viruses using electrochemical impedance spectroscopy technique. The sensor was fabricated by electrochemically depositing Au nanoparticles on the in situ prepared single walled carbon nanotube (SWCNTs) arrays, followed by the self-assembly of single-stranded probe DNA on the SWCNTs/Au platform. The as-prepared electrochemical sensor could detect lower than 1 attomole complimentary hepatitis B single-stranded DNA (ssDNA), which corresponds to having 600 ssDNA molecules in a 1.0 mL sample. For a 1-base mismatched hepatitis B ssDNA, the experimental detection limit is 0.1 pmol. When being applied to detect 24-base papilloma virus ssDNA, the experimentally determined low detection limit is 1 attomole. In addition to the low detection limit, the SWCNTs/Au/ssDNA sensor also showed great stability, where after being kept in a refrigerator for a month at a temperature 4-8 °C its charge transfer resistance decreased by less than 1%. The sensor could be conveniently regenerated via dehybridization in hot water. Both aligned and random SWCNTs arrays have been investigated in this study and there was nearly no difference in the low limit in the detection of hepatitis B and papilloma viruses. This study illustrates that combining Au nanoparticles with the in situ fabricated SWCNTs array is a promising platform for ultrasensitive biosensing.