24 June 1993 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
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Proceedings Volume 1891, Advances in DNA Sequencing Technology; (1993) https://doi.org/10.1117/12.146703
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States
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.
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Lawrence A. Bottomley, Lawrence A. Bottomley, J. A. Jones, J. A. Jones, Youzhen Ding, Youzhen Ding, David P. Allison, David P. Allison, Thomas G. Thundat, Thomas G. Thundat, R. J. Warmack, R. J. Warmack, } "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", Proc. SPIE 1891, Advances in DNA Sequencing Technology, (24 June 1993); doi: 10.1117/12.146703; https://doi.org/10.1117/12.146703
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