Electrochemical DNA sensors on the basis of electropolymerized thionine and Azure B with addition of pillar[5]arene as an electron transfer mediator

A DNA sensor was developed on the basis of glassy carbon electrode coated with polymeric forms of thionine and Azure B. Introduction of carbon black and pillar[5]arene into the electrode composition increases the efficiency of polymerization and the oxidation peak currents of dyes due to the mediating effect of the macrocycle. The addition of DNA onto the sensor surface and into the reaction mixture differently influences the electrochemical activity of poly(Azure B) and polythionine. The control of changes in current-voltage characteristics allowed us to identify the heat denaturation of DNA and its oxidation by reactive oxygen species generated upon the reaction of hydrogen peroxide and copper(II) salt. The DNA sensors can find application in the diagnosis of DNA damage on exposure to carcinogens and in screening of cytotoxic anticancer drugs.