Submolecular Structure and Orientation of Oligonucleotide Duplexes Tethered to Gold Electrodes Probed by Infrared Reflection Absorption Spectroscopy: Effect of the Electrode Potentials.
Unique electronic and ligand recognition properties of the DNA double helix provide basis for DNA applications in biomolecular electronic and biosensor devices. However, the relation between the structure of DNA at electrified interfaces and its electronic properties is still not well understood. Here, potential-driven changes in the submolecular structure of DNA double helices composed of either adenine-thymine (dAdT)25or cytosine-guanine (dGdC)20base pairs tethered to the gold electrodes are for the first time analyzed by in situ polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) performed under the electrochemical control. It is shown that the conformation of the DNA duplexes tethered to gold electrodes via the C6alkanethiol linker strongly depends on the nucleic acid sequence composition. The tilt of purine and pyrimidine rings of the complementary base pairs (dAdT and dGdC) depends on the potential applied to the electrode. By contrast, neither the conformation nor orientation of the ionic in character phosphate-sugar backbone is affected by the electrode potentials. At potentials more positive than the potential of zero charge (pzc), a gradual tilting of the double helix is observed. In this tilted orientation, the planes of the complementary purine and pyrimidine rings lie ideally parallel to each other. These potentials do not affect the integral stability of the DNA double helix at the charged interface. At potentials more negative than the pzc, DNA helices adopt a vertical to the gold surface orientation. Tilt of the purine and pyrimidine rings depends on the composition of the double helix. In monolayers composed of (dAdT)25molecules the rings of the complementary base pairs lie parallel to each other. By contrast, the tilt of purine and pyrimidine rings in (dGdC)20helices depends on the potential applied to the electrode. Such potential-induced mobility of the complementary base pairs can destabilize the helix structure at a submolecular level. These pioneer results on the potential-driven changes in the submolecular structure of double stranded DNA adsorbed on conductive supports contribute to further understanding of the potential-driven sequence-specific electronic properties of surface-tethered oligonucleotides.
Interdisciplinary Nanoscience Center (iNANO) and Center for DNA Nanotechnology (CDNA), Science and Technology, Aarhus University , Gustav Wieds Vej 14, DK-8000 Aarhus-C, Denmark.
László
L
Kékedy-Nagy
Interdisciplinary Nanoscience Center (iNANO) and Center for DNA Nanotechnology (CDNA), Science and Technology, Aarhus University , Gustav Wieds Vej 14, DK-8000 Aarhus-C, Denmark.
Elena E
0000-0003-1177-3204
EE
Ferapontova
Department of Chemistry, University of Oldenburg , 26111 Oldenburg, Germany.
Izabella
0000-0002-7710-0021
I
Brand
D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D004566:Electrodes; D055590:Electromagnetic Phenomena; D006046:Gold / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
D009838:Oligodeoxyribonucleotides; D006046:Gold; D004247:DNA