Atomic force microscopy of DNA in aqueous solutions

Helen G. Hansma, Magdalena Bezanilla, Frederic Zenhausern, Marc Adrian, Robert L. Sinsheimer

Research output: Contribution to journalArticle

167 Scopus citations

Abstract

DNA on mica can be imaged in the atomic force microscope (AFM) in water or in some buffers If the sample has first been dehydrated thoroughly with propanol or by baking in vacuum and if the sample is imaged with a tip that has been deposited in the scanning electron microscope (SEM). Without adequate dehydration or with an unmodified tip, the DNA is scraped off the substrate by AFM-imaging in aqueous solutions. The measured heights and widths of DNA are larger in aqueous solutions than in propanol. The measured lengths of DNA molecules are the same in propanol and in aqueous solutions and correspond to the base spacing for B-DNA, the hydrated form of DNA; when the DNA is again imaged in propanol after buffer, however, It shortens to the length expected for dehydrated A-DNA. Other results include the imaging of E.coli RNA polymerase bound to DNA in a propanol water mixture and the observation that washing samples in the AFM is an effective way of disaggregating salt-DNA complexes. The ability to image DNA in aqueous solutions has potential applications for observing processes involving DNA in the AFM.

Original languageEnglish (US)
Pages (from-to)505-512
Number of pages8
JournalNucleic acids research
Volume21
Issue number3
DOIs
StatePublished - Feb 11 1993
Externally publishedYes

ASJC Scopus subject areas

  • Genetics

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    Hansma, H. G., Bezanilla, M., Zenhausern, F., Adrian, M., & Sinsheimer, R. L. (1993). Atomic force microscopy of DNA in aqueous solutions. Nucleic acids research, 21(3), 505-512. https://doi.org/10.1093/nar/21.3.505