http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

http://chemotaxis.semmelweis.hu/CHTXhpg/Durotaxis/LoCM_BiophysJ_2000.pdf

Cell Movement Is Guided by the Rigidity of the Substrate

Dynamic strength of molecular adhesion bonds.

Biological materials: Structure and mechanical properties

Dynamic atomic force microscopy methods

Since its invention a few years ago, the atomic force microscope has become one of the most widely used near-field microscopes. Surfaces of hard sample are imaged routinely with atomic resolution. Soft samples, however, remain challenging. An overview is presented on the application of atomic force microscopy to organic samples ranging from thin ordered films at molecular resolution to living cells. Fundamental mechanisms of the image formation are discussed, and novel imaging modes are introduced that exploit different aspects of the tip-sample interaction for local measurements of the micromechanical properties of the sample. As examples, images of Langmuir-Blodgett films, which map the local viscoelasticity as well as the friction coefficient, are presented.

From molecules to cells: imaging soft samples with the atomic force microscope

Tapping mode atomic force microscopy in liquids gives a substantial improvement in imaging quality and stability over standard contact mode. In tapping mode the probe‐sample separation is modulated as the probe scans over the sample. This modulation causes the probe to tap on the surface only at the extreme of each modulation cycle and therefore minimizes frictional forces that are present when the probe is constantly in contact with the surface. This imaging mode increases resolution and reduces sample damage on soft samples. For our initial experiments we used a tapping frequency of 17 kHz to image deoxyribonucleic acid plasmids on mica in water. When we imaged the same sample region with the same cantilever, the plasmids appeared 18 nm wide in contact mode and 5 nm in tapping mode.

Tapping mode atomic force microscopy in liquids

Measuring the viscoelastic properties of human platelets with the atomic force microscope

The height fluctuations on top of the protein lysozyme adsorbed on mica were measured locally with an atomic force microscope operated in tapping mode in liquid. Height fluctuations of an apparent size of 1 nanometer that lasted for about 50 milliseconds were observed over lysozyme molecules when a substrate (oligoglycoside) was present. In the presence of the inhibitor chitobiose, these height fluctuations decreased to the level without the oligoglycoside. The most straightforward interpretation of these results is that the height fluctuations correspond to the conformational changes of lysozyme during hydrolysis. It is also possible, however, that the height fluctuations are, at least in part, the result of a different height or elasticity of the transient complex of lysozyme plus the substrate.

https://science.sciencemag.org/content/sci/265/5178/1577.full.pdf

Monika Fritz

Papers

From molecules to cells: imaging soft samples with the atomic force microscope

Tapping mode atomic force microscopy in liquids

Measuring the viscoelastic properties of human platelets with the atomic force microscope

Direct observation of enzyme activity with the atomic force microscope

Imaging soft samples with the atomic force microscope: gelatin in water and propanol