Near-field optical and shear-force microscopy of single fluorophores and DNA molecules

Ultramicroscopy. 1998 Mar;71(1-4):311-9. doi: 10.1016/s0304-3991(97)00086-7.

Abstract

Photodynamics of individual fluorescence molecules has been studied using an aperture-type near-field scanning optical microscope with two channel fluorescence polarisation detection and tuning fork shear-force feedback. The position of maximum fluorescence from individual molecules could be localised with an accuracy of 1 nm. Dynamic processes such as translational and rotational diffusion were observed for molecules adsorbed to a glass surface or embedded in a polymer host. The in-plane molecular dipole orientation could be determined by monitoring the relative contribution of the fluorescence signal in the two perpendicular polarised directions. Rotational dynamics was investigated on 10 ms-1000 s timescale. Shear-force phase feedback was used to obtain topographic imaging of DNA fragments, with a lateral and vertical resolution comparable to scanning force microscopy. A DNA height of 1.4 nm has been measured, an indication of the non-disturbing character of the shear force mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA / ultrastructure*
  • Fluorescence Polarization
  • Microscopy / instrumentation*
  • Microscopy / methods*
  • Microscopy, Electron, Scanning
  • Microscopy, Fluorescence / instrumentation
  • Microscopy, Fluorescence / methods*
  • Photons
  • Sensitivity and Specificity

Substances

  • DNA