Orienting DNA helices on gold using applied electric fields

Shana O. Kelley*, Jacqueline K. Barton, Nicole M. Jackson, Lee D. McPherson, Aaron B. Potter, Eileen M. Spain, Michael J. Allen, Michael G. Hill

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

252 Scopus citations

Abstract

Gold surfaces modified with thiol-derivatized DNA duplexes have been investigated as a function of applied electrochemical potential via atomic force microscopy (EC-AFM). At open circuit, monolayers of well-packed DNA helices form with a film depth of 45(3) angstroms. On the basis of the anisotropic dimensions of these 15 base pair duplexes (20 angstroms in diameter versus 50 angstroms in length), this corresponds to an average approximately 45° orientation of the helical axis with respect to the gold surface. Under potential control, the monolayer thickness (and therefore the orientation of the helices) changes dramatically with applied potential. At potentials negative of approximately 0.45 V (versus a Ag wire quasi-reference electrode) film thicknesses of approximately 55 angstroms are observed, whereas at more positive potentials the monolayer thickness drops to a limiting value of approximately 20 angstroms. These results are consistent with a morphology change in which the helices either stand straight up or lie flat down on the metal surface, depending on the electrode potential relative to the potential of zero charge (pzc). This voltage-induced morphology change is reversible and effectively constitutes a nanoscale mechanical `switch'.

Original languageEnglish (US)
Pages (from-to)6781-6784
Number of pages4
JournalLangmuir
Volume14
Issue number24
DOIs
StatePublished - Jan 1 1998
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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