Adsorbate deformation as a contrast mechanism in STM images of biopolymers in an aqueous environment: Images of the unstained, hydrated DNA double helix

Stuart Lindsay, T. Thundat, L. Nagahara

Research output: Contribution to journalArticle

Abstract

A stable residual aggregate remains on a submerged gold surface after electrophoretic deposition of DNA. We present scanning tunnelling microscope (STM) images of these aggregates which show many objects with the geometry of DNA, clearly displaying the 3·4 nm helix pitch. These images are quite distinctive, and cannot be generated when the deposition technique is used without DNA in the buffer solution. A characteristic of these images is that the tip is observed to dip down over the DNA molecule at the same time as the apparent barrier height drops by a factor of about four. The tip displacement is accounted for by a model in which contrast is dominated by local fluctuations in the deformability of the adsorbate layer, a quantity deduced from measurements of the apparent barrier heights in air, water, over small molecule adsorbates, and over DNA. 1870 Blackwell Science Ltd

Original languageEnglish (US)
Pages (from-to)213-220
Number of pages8
JournalThe Monthly Microscopical Journal
Volume3
Issue number2
DOIs
StatePublished - 1870

Keywords

  • DNA structure
  • liquid‐metal interfaces
  • scanning tunnelling microscopy

ASJC Scopus subject areas

  • Histology
  • Pathology and Forensic Medicine

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