• Double stranded DNA;
  • Dodecyltrimethylammonium bromide;
  • Tetradecyltrimethylammonium bromide;
  • Carbon nanotubes;
  • Carbon paste electrodes


Direct electrochemistry of dsDNA based on the enhancement effect of cationic surfactants such as dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB) was achieved by using a carbon paste electrode modified with multiwalled carbon nanotubes (MWCNTs/CPE) as the basal electrode. The results indicated that the dsDNA molecules have been adsorbed quite strongly on the cationic surfactants’ film and very well developed peaks which were attributed to the oxidation of guanine residues on the dsDNA molecule structure were obtained from both electrodes. The electrochemical behavior of dsDNA at the surface of the modified electrodes was also evaluated. Based on the signal of guanine, under the optimal conditions, very low levels of dsDNA were detected following short accumulation times with detection limits of 0.650 mg L−1 and 0.119 mg L−1 for DTAB/MWCNTs/CPE and TTAB/MWCNTs/CPE, respectively.