Topography, roughness, and the mechanical properties of biomaterials are crucial parameters that affect cell adhesion/motility, morphology, and mechanics as well as the proliferation of stem/progenitor cells. The nanomechanical analysis of cells and tissue slices is increasingly gaining in importance in various fields of cell biology, ranging from cancer research to developmental biology. Atomic force microscopy (AFM) is a powerful, multipurpose technology suitable not only for nanometer-scale imaging but also for mapping the mechanical and adhesive properties of sample/cell systems and tissues under controlled environmental conditions.
To address the task of providing modern AFM techniques, we recently developed a new imaging mode called “Quantitative Imaging” (QI™) which is based on fast force-distance curves. QI allows the user to simultaneously determine the topographic, nanomechanical, and adhesive properties of a sample. In addition to this classical information, this method yields more complex information like contact point, Young´s modulus, and molecular recognition data. Notably, the QI™ mode enables superior imaging of challenging biological samples which are soft, fragile or loosely attached, e.g. viruses, bacteria or diatoms.
Modern AFM techniques have fast imaging capabilities which enable the acquisition of complete AFM images within seconds. This allows for the visualization of time-dependent processes, e.g., cytoskeleton motion, membrane dynamics, and the dynamic effects of supra-molecular protein assemblies.
To directly observe the region between the front-most part of a cantilever and an object being investi-gated during force-spectroscopy experiments by means of functionalized cantilevers, a purpose-built cantilever holder is used. Replacing standard cantilevers by micro-channeled probes enables microfluidic control, e.g., the injection of drugs/genes into individual cells.
Combining modern AFM techniques with super-resolution optical techniques, such as Stimulated Emission Depletion Microscopy, STED, allows the even more detailed study of living matter: (i) the measurement of interaction forces and nanomechanical properties, or the performance of sample manipulation/stimulation experiments using AFM, and (ii) the determination of subcellular structures and biochemical specificity with high spatiotemporal resolution by means of super-resolution optical techniques.