engleski

Marine diatom cells and extracellular polymers: nanostructure, nanomechanics and interactions with nanoparticles

Atomic Force Microscopy (AFM) connects the nanometer and micrometer length scales utilizing a sharp probe tip that senses interatomic forces acting between the surface of a sample and the atoms at the apex of the tip. The physical basis behind AFM and its ability to „feel“ the surface, make AFM a versatile tool in biophysics allowing high resolution imaging, nanomechanical characterization and measurements of inter and intramolecular forces in living and non-living structures. The potential of AFM as a tool in marine ecology will be presented. The nanomechanical properties (elasticity and deformation) of a weakly silicified marine diatom Cylindrotheca closterium were characterized using a novel AFM imaging technique, Peak Force Tapping. The nanomechanical properties were measured over the entire surface of live cell in seawater and revealed nanostructure was related to the cell wall function. Diatom extracellular polymers were visualized as fine fibrils forming networks down to the molecular level using a high resolution imaging. The single molecule force spectroscopy was applied to probe the mechanical response of the polysaccharide fibrils and to quantify inter and intramolecular forces within the network. A preliminary data will be shown. Finally, unknown interactions of Ag NPs with diatom cells and their extracellular polymers were identified. High- resolution topographical imaging revealed details of Ag NP–cell wall interaction and incorporation of Ag NPs in the extracellular polysaccharide network produced by diatom.

marine diatoms; extracellular polymers; AFM; nanostructure; nanomechanics

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