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High speed atomic force microscopy of biomolecules by image tracking
S J van Noort1, K O van Der Werf, B G de Grooth
1Department of Applied Physics, University of Twente, 7500 AE Enschede, The Netherlands.
Biophysical Journal
|October 8, 1999
Summary
This study introduces an atomic force microscopy (AFM) image-tracking method to prevent drift, enabling detailed observation of DNA diffusion. The new technique allows high-speed imaging of DNA plasmids, revealing their movement patterns on surfaces.
Area of Science:
- Atomic Force Microscopy (AFM)
- Surface Science
- Biophysics
Background:
- Atomic Force Microscopy (AFM) is crucial for nanoscale imaging.
- Lateral drift in AFM hinders long-term observation of dynamic processes.
- Tracking individual molecules over time requires precise drift correction.
Purpose of the Study:
- To develop and validate an image-tracking procedure for AFM to overcome lateral drift.
- To enable high-resolution, long-term imaging of dynamic nanoscale events.
- To analyze the diffusion of DNA molecules with unprecedented temporal resolution.
Main Methods:
- An on-line cross-correlation algorithm was implemented for real-time drift correction.
- The image-tracking procedure was applied to atomic force microscopy.
- The method was tested by imaging 5.4-kb DNA plasmids on a mica surface.
Main Results:
- The image-tracking procedure successfully minimized lateral drift to less than 10 nm over 30 minutes.
- High frame rates (4 s/frame) were achieved for small scan areas (500x500 nm^2).
- A diffusion coefficient of 30 nm^2/s was determined for DNA molecules, with some exhibiting temporary surface pinning.
Conclusions:
- The developed image-tracking method significantly enhances AFM capabilities for dynamic studies.
- This technique allows detailed analysis of DNA diffusion dynamics at the nanoscale.
- Observed diffusion coefficients and surface interactions provide insights into DNA-surface interactions.