engleski

Quantitative nanomechanical mapping of marine diatom in seawater by Peak Force Tapping AFM

Apart from diatom ecological significance, diatoms are mainly known for the intricate geometries and spectacular patterns of their silica-based walls. These patterns are species specific. Diatoms cell walls are composed of silica and organic components and show a complex microscopic structure. Understanding how organic matter is associated with the silica structure could provide an important insight into biomineralization process and patterning on the unicellular level. Here we have selected weakly silicified, pennate, marine diatom Cylindrotheca closterium (strain CCNA1), isolated from Nothern Adriatic. The unique characteristic of the cell wall of Cylindrotheca spp. are regions (valve), which are believed to be completely unsilificied, thus consisting of purely organic material. This makes them ideal candidates for studying structure and organization of organic and inorganic domains of cell walls. This study highlights the capacity of Peak Force Tapping, a new AFM imaging mode, for investigating nanomechanical properties of different regions in marine diatoms, providing high resolution quantitative maps. As a result, we have correlated differences in mechanical properties with assumed composition (organic domains, silica regions) and morphology of diatom cell walls. These findings are in accordance with our AFM results obtained on “organic free” diatom cell walls.

atomic force microscopy (AFM); Cylindrotheca closterium; deformation; diatom cell wall; elasticity; marine diatom; nanomechanical properties; Peak Force Tapping AFM; Young’s modulus

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