engleski

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

It is generally accepted that a diatom cell wall is characterized by a siliceous skeleton covered by an organic envelope essentially composed of polysaccharides and proteins. Understanding of how the organic component is associated with the silica structure provides an important insight into the biomineralization process and patterning on the cellular level. We have selected weakly silicified marine diatom Cylindrotheca closterium. The unique characteristics of Cylindrotheca spp. cell wall are regions which are believed to be completely unsilicified. The nanomechanical properties were measured over the entire cell surface in seawater at a resolution that was not achieved in previous studies of marine diatoms. Based on nanomechanical mapping of diatom cell wall we discovered silica nanoparticles in the valve region that has been reported to be unsilicified and purely organic. A cell wall model is proposed with individual silica nanoparticles incorporated in an organic matrix. Such organization of girdle band and valve regions enables the high flexibility needed for movement and adaptation to different environments while maintaining the integrity of the cell.

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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