title: Electrochemical impedance probing of DNA hybridisation on oligonucleotide-functionalised polypyrrole.
abstract: We report a new approach for detecting DNA hybridisation using non faradaic electrochemical impedance spectroscopy. The technique was applied to a system of DNA probes bearing amine groups that are immobilized by covalent grafting on a supporting polypyrrole matrix functionalised with activated ester groups. The kinetics of the attachment of the ss-DNA probe was monitored using the temporal evolution of the open circuit potential (OCP). This measurement allows the determination of the time necessary for the chemical reaction of ss-DNA probe into the polypyrrole backbone. The hybridisation reactions with the DNA complementary target and non complementary target were investigated by non faradaic electrochemical impedance spectroscopy. Results show a significant modification in the Nyquist plot upon addition of the complementary target whereas, in presence of the non complementary target, the Nyquist plot is not modified. The spectra, in the form of Nyquist plot, were analysed with the Randles circuit. The transfer charge resistance R(2) shows a linear variation versus the complementary target concentration. Sensitivity and detection limit (0.2nM) were determined and detection limit was lower of one order of magnitude than that obtained with the same system and measuring variation of the oxidation current at constant potential.
authors.affiliation: Cegely, UMR-CNRS 5005, EC-Lyon, 69134 Ecully Cedex, France; Laboratoire de Chimie Bioorganique et Bioinorganique UMR-CNRS 8124, Institut de Chimie Moléculaire et Matériaux d'Orsay, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Chaker
authors.initials: C
authors.lastname: Tlili
authors.forename: Hafsa
authors.initials: H
authors.lastname: Korri-Youssoufi
authors.forename: Laurence
authors.initials: L
authors.lastname: Ponsonnet
authors.forename: Claude
authors.initials: C
authors.lastname: Martelet
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Jaffrezic-Renault