In addition, AFM allows the measurement of forces with remarkable sensitivity and positional precision. In this mode, known as force spectroscopy, the cantilever deflection is recorded as the tip is pushed towards the sample and retracted from it. Force spectroscopy can be used to probe quantitatively physical properties such as local elasticity, surface forces, surface charges and hydrophobicity. This technique allows to measure inter- and intramolecular interactions, thus providing new insights into the molecular bases of biological processes such as protein folding and receptor–ligand interactions.
With the help of the AFM (and some other techniques such as Biacore, Langmuir monolayers, fluorescence spectroscopy), my scientific interest is focused on:
the interaction of proteins with surfaces and specific ligands
the interaction of external agents with biomembranes
Simplified artificial structures which mimic the biological membranes were developed and characterized during the past decade. Among these biomimetic systems, biomembranes supported on solid substratum allowed the characterization of biological interactions with tools and techniques designed for surfaces, such as the atomic force microscopy (AFM). These types of lipid bilayers can be prepared by using two methods: the Langmuir-Blodgett transfer of monolayers, or the fusion of preformed vesicles.
During the past two decades, the AFM has provided new avenues for microscopists to study biological specimens and it is now established as a versatile tool to address the structure, properties and functions of biological specimens. AFM is unique in that it provides three-dimensional images of biological structures, including biomolecules, lipid films, 2D protein crystals and living cells, under physiological conditions and with unprecedented (sub)nanometer resolution.