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Transport électronique dans l'ADN

Abstract : Electronic transport in DNA This work belongs to the field of molecular electronics. Questions about the electric conduction in DNA was firstly put in 1962 by Eley and Spivey, after the discovery of the double helix structure of DNA by Watson and Crick in 1953. Until now, no consensus has emerged about the electric properties of DNA. Charge transfers over nanometric distances have been studied in solution and are quite well understood. However, direct measurements between electrodes present various behaviors, from induced supraconductivity to insulator or semiconductor. This debate is at the basis of our work. We have studied the electronic properties of DNA deposited over different self-assembled molecular layers on silicon substrates. The first part of the study deals with the preparation of the surface and deposition of DNA. Then, conductivity of DNA is measured between electrodes built on an insulating substrate or thanks to a conducting AFM. In this last case, the AFM tip allows to image the surface and to be used as a second electrode during the electrical measurement. Two kinds of results have been obtained : insulating to conducting behaviors are observed. Resistances are spread out over at least 6 orders of magnitude, from 109 W to 1015 W, but with a lower frequency of appearance for high conductivities. Two points can be put forward to explain such a disparity : on the one hand, production of an electrical contact between the electrode and DNA, on the other hand, DNA deposition method over the surface. Formation of an electrical contact between the electrode and DNA implies some treatments which usually destroy the molecules. This contact can be improved by using piles of DNA molecules to link the evaporated electrode and the studied DNA rope. However, this method adds a high series resistance. Systematic measurements have been realized according to the distance of the AFM tip to the pile of DNA molecules, and to the estimated number of DNA strands in the rope. DNA deposition being a primordial parameter, this point is deeper studied to understand the link between DNA structure and its properties of conduction. Keywords : Molecular electronics, nanobiotechnology, DNA, deposition of DNA, Atomic Force Microscope, conducting AFM, self-assembled monolayer
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Contributor : Thomas Heim <>
Submitted on : Wednesday, December 10, 2003 - 4:52:37 PM
Last modification on : Wednesday, February 17, 2021 - 10:58:06 AM
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  • HAL Id : tel-00003954, version 1

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Thomas Heim. Transport électronique dans l'ADN. Biophysique [physics.bio-ph]. Université des Sciences et Technologie de Lille - Lille I, 2002. Français. ⟨tel-00003954⟩

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