Electrochemical DNA Sensing at Single-walled Carbon Nanotubes Chemically Assembled on Gold Surfaces

An electrochemical DNA sensor was constructed using single-walled carbon nanotubes (SWNTs) attached to a self-assembled monolayer of 11-amino-1-undecanethiol on a gold surface. The voltammetric peak of methylene blue (MB), which interacts with the DNA guanine bases specifically, was used to follow the DNA hybridization process. After DNA hybridization with its complementary DNA strand, the MB electrochemical signal response decreased and the change in MB signal response was used as the basis for the electrochemical sensing of DNA hybridization. The as described DNA sensor demonstrated to have good stability, selectivity, a linear response over the DNA concentration range from 100 to 1,000 nM and a limit of detection of 7.24 nM.