Electrochemical detection of Cecropin CM4 gene by single stranded probe and cysteine modified gold electrode

A single stranded Cecropin CM4 gene (108 bases) was further immobilized at a cysteine modified gold electrode with the help of water soluble 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). The ssDNA at the modified electrode could undergo hybridization in a hybridization buffer containing single stranded plasmid pLCM-4SN. A DNA minor groove binder, Hoechst 33258, was employed to discriminate between ssDNA and dsDNA. The anodic waves in differential pulse voltammograms (DPVs), of Hoechst 33258 bound to the DNAs, were used as the indicator. This assay procedure was shown to be rapid, sensitive and precise, thus a kind of prototype DNA biosensor was developed.