Atomic Force Microscope (AFM)

We study cell wall structure using atomic force microscopy (AFM). Cell wall material is extracted from the tissue and observed on a glass or mica support, either in air or liquid. AFM allows for the observation of surface topology, thus the images obviously provide a limited overview of cell wall assembly. Therefore, to study individual polysaccharides, samples are prepared as extracts according to their solubilization in different reagents. This allows for the study of water (WSP), chelator (CSP) or sodium carbonate soluble pectins (DASP), hemicellulose and cellulose in the context of their structural attributes like diameter, length or branching index.

AFM allows us to study biological objects at the nano-scale. Besides scanning of surface topography, the AFM cantilever may work as a nano-indenter providing a force-distance curve. The force-indentation curve is then used to estimate stiffness (Young’s modulus). Moreover, the method can be used to obtain maps of stiffness over a sample. Since the AFM technique allows us to work with soft, living and small objects in a liquid environment, it is an interesting tool for studying plant cell wall and cell mechanics. We can use this method to study the mechanical properties of either isolated cell walls or a single living cell from fruit.