Applications in Nanoscience
A biological implementation of CFM at the nanoscale level is the unfolding of proteins with functionalized tip and surface (see Figure 5). Due to the increased contact area, the tip and the surface act as anchors holding protein bundles while they separate. As uncoiling ensues, the force required jumps indicating various stages of uncoiling: (1) separation into bundles, (2) bundle separation into domains of crystalline protein held together by van der Waals forces, and (3) linearization of the protein upon overcoming the secondary bonding. Information on the internal structure of these complex proteins, as well as a better understanding of constituent interactions are provided with this method.
A second consideration is one that takes advantage of unique nanoscale materials properties. The high aspect ratio of carbon nanotubes (easily >1000) is exploited to image surfaces with deep features.. The use of the carbon material broadens the functionalization chemistry since there are countless routes to chemical modification of nanotube sidewalls (e.g. with diazonium, simple alkyls, hydrogen, ozone/oxygen, and amines). Multiwall nanotubes are typically used for their rigidity. Because of their approximately planar ends, one can estimate the number of functional groups that are in contact with the substrate knowing tube diameter and number of walls which helps in determining single moiety tensile properties. Certainly, this method has obvious implications in tribology as well.
Read more about this topic: Chemical Force Microscopy