Scanning tunneling microscopy of DNA

The systematic removal or destruction of DNA by the scanning tunneling microscope (STM) stems from the low conductivity of the molecule. Imaging DNA at exceedingly low currents and high voltages prevents damaging contact in humid conditions. The STM images of DNA on mica are evidence that the STM could be used to study genomic structure on a nanometer scale. Thus, the STM may join the scanning force microscope as a powerful imaging tool for DNA studies because: 1) Such resolution is adequate for observing the curvature of DNA and DNA-protein complexes, and also the gross structure of DNA-protein complexes. 2) Both microscopes may be operated in solution to examine DNA molecules in physiological conditions. However, Lindsay et al. (1990) have encountered the above mentioned difficulties using the STM. 3) While the STM is sensitive to the electronic states of adsorbed molecules, the scanning force microscope can detect chemical parameters such as adhesion. Information in addition to topography enhances one's ability to interpret images. Undoubtedly, the scanning tunneling microscope is a very important tool with which to study conductive surfaces. For poorly conducting molecules adsorbed on substrates, hybrid microscopes with which to examine the surface by alterative methods may neatly facilitate systematic investigations.