Streptavidin Modified Carbon Nanotube Based Graphite Electrode for Label-Free Sequence Specific DNA Detection

Disposable graphite pencil electrodes (PGE) modified with multiwalled carbon nanotubes (MWCNTs)-streptavidin (STR) conjugates were used for electrochemical monitoring of label-free DNA hybridization. The surface morphology of PGE electrode before and after hybridization was characterized by scanning electron microscopy. Electrochemical impedance spectroscopy was used to monitor each step of the construction of the DNA biosensor. The biosensor was demonstrated to have excellent selectivity, being able to differentiate complementary sequences from a noncomplementary ones and in addition select the target sequence of DNA from a mixture of other DNA without loss in current sensitivity.