Scanning tunneling microscopy of mercapto-hexyl-oligonucleotides attached to gold

6-mercapto hexyl-oligonucleotides bind to a gold surface strongly enough to permit imaging by a scanning tunneling microscope (STM). STM images showed worm-like chains that were approximately 12-(A-wide for single-stranded DNA and 20-(A-wide for double-stranded DNA. The chain lengths corresponded to...

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Bibliographic Details
Published in:Biophysical journal 1996-08, Vol.71 (2), p.1079-1086
Main Authors: Rekesh, D., Lyubchenko, Y., Shlyakhtenko, L.S., Lindsay, S.M.
Format: Article
Language:English
Subjects:
Base Composition
Base Sequence
DNA - chemistry
DNA - ultrastructure
DNA, Single-Stranded - chemistry
DNA, Single-Stranded - ultrastructure
Gold
Microscopy, Scanning Tunneling - methods
Oligodeoxyribonucleotides - chemical synthesis
Oligodeoxyribonucleotides - chemistry
Static Electricity
Sulfhydryl Compounds
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Summary:6-mercapto hexyl-oligonucleotides bind to a gold surface strongly enough to permit imaging by a scanning tunneling microscope (STM). STM images showed worm-like chains that were approximately 12-(A-wide for single-stranded DNA and 20-(A-wide for double-stranded DNA. The chain lengths corresponded to 3.4 +/- 0.4 A per basepair for double-stranded DNA and 2.2 +/- 0.4 A per base for single-stranded DNA. This unexpectedly short length for single-stranded DNA was confirmed using oligomers with both single- and double-stranded regions. When the attachment of the samples was weakened (by imaging in water or scraping with the STM tip) the images changed to pairs of "blobs," apparently reflecting the attachment points of the molecules to the gold surface. Given this interpretation, images of DNA containing a five-base bulge imply that the bulge bends the oligomer by 90 degrees +/- 20 degrees.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(96)79308-6