To elucidate the mechanism involved in the electrochemical transduction process of a conducting polymer-based DNA sensor, peptide nucleic acids (PNA) were used. PNA are DNA analogues having similar hybridization properties but are neutral. This allows to discriminate the electrostatic effect of DNA strands from the steric hindrance generated on the bioelectrode upon hybridization. It can be concluded that DNA conformational changes are determinant in the transduction process and that the electrostatic effect is negligible. (c) 2008 Elsevier Ltd. All rights reserved.