Molecular structure of DNA by scanning tunneling microscopy

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Science  15 Sep 1989:
Vol. 245, Issue 4923, pp. 1226-1227
DOI: 10.1126/science.2781279


Uncoated DNA molecules marked with an activated tris(l-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with the use of a high-resolution scanning tunneling microscope (STM). Constant-current and gap-modulated STM images show clear evidence of the helicity of the DNA structure: pitch periodicity ranges from 25 to 35 angstroms, whereas the average diameter is 20 angstroms. Molecular structure within a single helix turn was also observed.

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