Humidity effects on atomic force microscopy of gold-labeled DNA on mica

J. Vesenka, S. Manne, G. Yang, C. J. Bustamante, E. Henderson, R. Balhorn, B. L. Blackford, Z. Mulhern, J. Yang, T. Thundat, F. Zenhausern

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Recent work in atomic force microscopy (AFM) of deoxyribonucleic acid (DNA) has relied on immobilizing DNA molecules by drying a small volume of buffered DNA solution onto cleaved mica. When imaging in air, relative humidity has been known to affect both the resolution and measured height of the DNA strands. We present data of measured height versus humidity for DNA and attached gold labels, and we propose a model for this data based on swelling of coadsorbed buffer salts upon exposure to moisture. In this model, small particles (e.g., DNA) stay near the top of the swelling salt layer, whereas larger particles (e.g., gold spheres) tend to be anchored down to the substrate until a moderate humidity is reached. At high humidity (around 65%), the salt layer becomes fluid-like and susceptible to tip-induced motion; the salts are either removed from the scan area or aggregate into island structures, depending on initial salt concentration on the surface.

Original languageEnglish (US)
Pages (from-to)781-788
Number of pages8
JournalScanning Microscopy
Issue number3
StatePublished - Sep 1993


  • Atomic Force Microscope
  • DNA
  • colloidal gold particle
  • humidity
  • mica
  • salt

ASJC Scopus subject areas

  • Instrumentation


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