High-Speed AFM and Imaging of Biomolecular Processes

Department of Physics, Kanazawa University, Kakuma-machi Kanazawa, Ishikawa 920-1192, Japan tando staff.kanazawa-u.ac.jp 

This article presents recent progress in high-speed atomic force microscopy for dynamic imaging of biomolecular processes, including the theoretical basis for the highest possible imaging rate, instrumentation, hydrodynamic effects on cantilever oscillation, and various visualization studies on the dynamic molecular process and structure of proteins. 

The structure of proteins has thus far been studied by X-ray crystallography, electron microscopy (EM), nuclear magnetic resonance (NMR), or atomic force microscopy (AFM), but the obtained structures are substantially static. The d3mamic behavior of protein molecules has been studied at the single-molecule level using fluorescence microscopy, but the protein molecules themselves are 

Nanoscale Liquid Interfaces Wetting, Patterning, and Force Microscopy at the Molecular Scale Edited by Thierry Ondarguhu and Jean-Pierre Alme Copyright (c) 2013 Pan Stanford Publishing Pte. Ltd. 

It is mandatory in bio-AFM imaging that the tip-sample distance (hence, the tip-sample interaction force) be maintained constant by feedback control. When a sample is scanned over an area ofWy.W with scan velocity Vs in the x-direction and N scan lines in the y-direction, the image acquisition time T is given by T = 2WN/Vs. Supposing that the sample surface is characterized with a single spatial frequency 1/X, then the feedback scan is executed in the z-direction with frequency / = Vs/ . to trace the sample surface. 

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