Sample preparation and immobilization

Sample preparation will ultimately determine the quality of the images observed. For example, poorly prepared samples may show nothing but debris due to contamination of the surface. Cleanliness during sample preparation and imaging is therefore essential, and all aqueous solutions should be filtered prior to use (and at most used 1 month after preparation). 

It should also be noted that the method of surface attachment may also have an influence the properties of the biomolecule of interest. For example, while covalent attachment may facilitate the structural investigation of isolated biomolecular species, such a strong attachment may be disadvantageous if the user wishes to subsequently visualize any dynamic processes of this molecule, as they may be hindered/prevented. For the observation of such dynamic processes the use of immobilization methods such as weak electrostatic interaction is therefore more usual, and in this type of experiment thorough investigation and optimization of the immobilization process is absolutely essential. 

The recorded width of the dsDNA helix, for example, when analysed using AFM is typically 12-15 nm, whereas a width of 2 nm is predicted from the crystal structure. For specimens that are approximately circular in cross-section, it is sometimes 

As tip-sample convolution occurs due to the finite size of the probe, it is obvious that the effect would be reduced by further miniaturizing the probe s dimensions. With some success, recent attempts to achieve this goal have utilized single-walled carbon nanotubes attached to the apexes of regular AFM probes. Commercially available sharpened silicon oxide probes can also help improve the attainable level of resolution. 

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