title: Electrochemical detection of DNA hybridization by means of osmium tetroxide complexes and protective oligonucleotides.
abstract: We have utilized protective oligonucleotides to modify DNA fragments with osmium tetroxide complexes without compromising their ability to hybridize with immobilized thiol-linked probe-SAMs on gold electrodes. Due to reversible voltammetric signals of Os(VI/IV), this method allowed sensitive electrochemical hybridization detection of short (25 bases) and long (120 bases) thymine-containing DNA targets. The detection limit was 3.2 nM for the long target. We found an optimum 40 degrees C hybridization temperature for the short target. No interference by noncomplementary DNA was observed. At least 10 repetitive hybridization experiments at the same probe-SAM were possible with thermal denaturation in between. Such use of protective strands could be useful also for other types of DNA recognition and even for other DNA-modifying agents. Moreover, it is possible to produce electrochemically active oligonucleotides (targets and reporter probes) in ones own laboratory in a simple way.
authors.affiliation: Department of Chemistry, University of Rostock, Dr.-Lorenz-Weg 1, D-18059 Rostock, Germany. gerd-uwe.flechsig@uni-rostock.de
authors.forename: Gerd-Uwe
authors.initials: GU
authors.lastname: Flechsig
authors.forename: Thomas
authors.initials: T
authors.lastname: Reske
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization / Q000379:methods*; D009841:Oligonucleotides / Q000737:chemistry*; D009993:Osmium Tetroxide / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods*; D013941:Thymine / Q000032:analysis
chemical_list: D009841:Oligonucleotides; D004247:DNA; D009993:Osmium Tetroxide; D013941:Thymine