Impedimetric DNA-biosensor for the study of anti-cancer action of mitomycin C: Comparison between acid and electroreductive activation

An electrochemical protocol is described for direct monitoring of anti-cancer properties of MMC. Using electrochemical impedance spectroscopy, a pretreated pencil graphite electrode (PGE) modified with multiwall carbon nanotubes (MWCNTs) and poly(diallyldimethylmmonium chloride), PDDA, decorated with ds-DNA was employed in this study to identify DNA damages induced by MMC. The change in charge transfer resistance after incubation of the DNA-biosensor in MMC solution for a known time was used as indication of DNA damage. It was found that MMC did not interact with DNA. As MMC does not inherently possess any anti-cancer activity, it is, therefore, necessary to activate it by either of two ways: activation in acidic media or electrochemical activation. Incubation of DNA-modified electrode in activated MMC led to alterations in DNA and changes in its electrochemical properties (which forms the theme of the present study). Acid and electroreductive MMC activations were compared and different adducts were subsequently generated, suggesting that the drug can bind to DNA in more than one way. Impedance spectroscopy was used for the first time as a novel technique for detecting DNA-drug adducts.