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Proceedings Paper

Scanning tunneling microscopic imaging of electrostatically immobilized nucleic acids: the influence of self-assembled monolayer structure on the binding of plasmid DNA to gold surfaces
Author(s): Lawrence A. Bottomley; J. A. Jones; Youzhen Ding; David P. Allison; Thomas G. Thundat; R. J. Warmack
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Paper Abstract

Alkanethiols self-assemble into monolayers on gold surfaces. It has been shown that gold surfaces derivatized with two-carbon, bifunctional alkanethiols differentially adsorb DNA. Gold surfaces modified with either 2-(N,N-dimethylamino)ethanethiol or 2-aminoethanethiol immobilized DNA at solution pH's where the amino end groups are protonated. The cationic layer holds the DNA in place by ion-pairing with the negatively-charged phosphate groups on the DNA backbone. This ion-pairing is sufficiently strong to resist changes in the DNA's location and conformation induced by the scanning tunneling microscope (STM) tip. With these chemically modified surfaces, the reliable and reproducible imaging of DNA is possible. When the length of the alkane spacer is increased to eleven carbons, the observed affinities for radiolabeled DNA are comparable to that observed for the two carbon spacer. However, clearly resolved STM images of DNA immobilized on 11-(N,N'-dimethylamino)- undecanethiol-modified gold have not been obtainable. We hypothesize that images of immobilized DNA are not observed because of the interaction of the scanning probe with the self-assembled alkanethiol monolayer.

Paper Details

Date Published: 24 June 1993
PDF: 8 pages
Proc. SPIE 1891, Advances in DNA Sequencing Technology, (24 June 1993); doi: 10.1117/12.146703
Show Author Affiliations
Lawrence A. Bottomley, Georgia Institute of Technology (United States)
J. A. Jones, Georgia Institute of Technology (United States)
Youzhen Ding, Georgia Institute of Technology (United States)
David P. Allison, Oak Ridge National Lab. (United States)
Thomas G. Thundat, Oak Ridge National Lab. (United States)
R. J. Warmack, Oak Ridge National Lab. (United States)

Published in SPIE Proceedings Vol. 1891:
Advances in DNA Sequencing Technology
Richard A. Keller, Editor(s)

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