title: Interaction of viologens with nucleic acid G-tetrades.
abstract: The interaction between the tetrade-forming oligonucleotide 5'-d(T 4G 4T 4) and monoalkylated bipyridinium salts, such as 1-ethyl-4-pyridin-4-ylpyridinium bromide, is reported. The oligomer forms tetrades in the presence of K+ ions but not with Li+. Additionally, the interaction of the thrombin-binding aptamer 5'-d(GGTTGGTGTGGTTGG) (TBA) with a dialkylated bipyridinium salt, viologen, was studied by cyclic voltammetry. This was performed either on a TiO2 electrode, derivatized with 3-aminopropyltriethoxysilane (APS), using [Fe(CN)6](4-) as a marker ion or without a marker ion on an electrostatically TiO2-bound amino-ferrocenyl derivative. Both experiments proof a strong interaction between the immobilized aptamer and the viologen. Third, the electrochemical response of the specific thrombin binding to the immobilized aptamer was studied.
authors.affiliation: Institute of Chemistry, University of Osnabrück, Barbarastrasse 7, 49076 Osnabrück, Germany. sasaftei@uos.de
authors.forename: Simona
authors.initials: S
authors.lastname: Asaftei
authors.forename: Helmut
authors.initials: H
authors.lastname: Rosemeyer
authors.forename: Lorenz
authors.initials: L
authors.lastname: Walder
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods; D008094:Lithium / Q000737:chemistry; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D013917:Thrombin / Q000737:chemistry; D014755:Viologens / Q000737:chemistry*
chemical_list: D052157:Aptamers, Nucleotide; D009838:Oligodeoxyribonucleotides; D014755:Viologens; D008094:Lithium; D013917:Thrombin; D011188:Potassium