Electrochemically controlled binding of ethidium to calf thymus DNA at a carbon-paste / ethidium tetracyanoquinodimethane electrode

Abstract

Ethidium tetracyanoquinodimethane, Et-TCNQ, carbon paste composite electrodes have been fabricated and studied in contact with aqueous solution. Low current efficiencies for the potential-dependent release of ethidium cations from the electrode surface were observed. In the presence of calf thymus DNA in solution, potential-dependent intercalation of ethidium from the electrode surface was demonstrated by detection of the fluorescence of the intercalated ion. The maximum fluorescence intensity was linear with DNA concentration over the range from 3 to 150 ppm calf thymus DNA.