title: Distinguishing cytosine methylation using electrochemical, label-free detection of DNA hybridization and ds-targets.
abstract: In this communication we report on two important effects related to the detection of DNAs. Firstly, we investigate the sensor response to target DNA when the target is in a double stranded (ds) form and compare the response to single stranded (ss) target DNA. The importance in evaluating such an effect lies in the fact that most biological DNA targets are found in ds form. Secondly, we use synthetic ds targets to investigate the effect of DNA methylation on the sensor response. DNA methylation is known to affect functional properties of DNA and is related to a number of diseases, including various cancers. In these studies, we utilize our previously developed sensor platform, which is based on the use of a glassy carbon electrode-confined conducting polymer that is covalently modified with DNA probe sequences. The signal detection methodology we use is measuring a change in the reaction kinetics of ferro-ferricyanide redox couple at the electrode upon hybridization by means of electrical impedance spectroscopy (EIS). Additionally, EIS is utilized to study the kinetics of the hybridization of the conducting polymer-bound probe with methylated vs. non-methylated ds-DNA. Preliminary results are proving valuable as a guide to the future design of sensors for gene methylation.
authors.affiliation: Polymer Electronics Research Centre (PERC), School of Chemical Sciences, University of Auckland, 23 Symonds Street, Auckland, New Zealand.
authors.forename: Bicheng
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Digital Sensing Limited, 16 Beatrice Tinsley Cresent, Albany, Auckland 0632, New Zealand.
authors.forename: Marsilea A
authors.initials: MA
authors.lastname: Booth
authors.affiliation: Liggins Institute, University of Auckland, Building 505, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Phillip
authors.initials: P
authors.lastname: Shepherd
authors.affiliation: Liggins Institute, University of Auckland, Building 505, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Allan
authors.initials: A
authors.lastname: Sheppard
authors.affiliation: Polymer Electronics Research Centre (PERC), School of Chemical Sciences, University of Auckland, 23 Symonds Street, Auckland, New Zealand; MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.
authors.forename: Jadranka
authors.initials: J
authors.lastname: Travas-Sejdic
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003596:Cytosine / Q000032:analysis*; D004247:DNA / Q000032:analysis* / Q000737:chemistry; D019175:DNA Methylation; D058266:Dielectric Spectroscopy / Q000379:methods; D009693:Nucleic Acid Hybridization / Q000379:methods
chemical_list: D003596:Cytosine; D004247:DNA
keywords: DNA methylation; Double-stranded target; Electrochemical impedance spectroscopy; Hybridization kinetics