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TU Dresden » Faculty of Science » Department of Chemistry and Food Chemistry » Bioanalytical Chemistry

Examinations of Biomineralisation of Diatoms by means of biological Solid-State NMR

The term "biomineralisation" denotes the formation of inorganic material under the control of an organism. The main function of these biominerals is the stabilisation and protection of the soft organic tissue. Examples are the calcium phosphates of bones and teeth of vertebrate animals as well as the shells of mussels or algae consisting of calcium carbonate or silica. These biominerals exhibit remarkable material properties. Today, the industrial production of these materials is hardly possible. Therefore, it is important to analyse and understand the basic processes and principles of biomineralisation in nature.

 

Diatoms are unicellular, photosynthetic eukaryotes, which can be found in sea as well as in freshwater. They play a crucial role in the fixation of CO2 and circulation of SiO2 in the oceans. However, their most striking feature is their art-specific silicified cell wall which exhibits beautiful, regularly structured patterns which and precisely reproduced during each cell division. Diatom cell walls consist of inorganic amorphous hydrated silica. In addition, certain organic components can be found which are closely attached to the inorganic material. These organic components are supposed to play a key role in the formation of highly structured cell walls.

Within this project our group analyses the process of biosynthesis of amorphous silica in diatoms in cooperation with the Biochemistry (Prof. Dr. Karl-Heinz van Pée). Especially by using modern solid-state NMR spectroscopic techniques, we investigate the silica metabolism in diatoms as well as the contribution of biomolecules in process of silica deposition. For example, we studied the self-assembly of polyamines (PA) by P-31 NMR spectroscopy. PA are organic molecules which can be found in cell walls of diatoms. Changes of the chemical shift and linewidth indicate the binding of phosphate to PA and the aggregation of PA molecules. It is tempting to speculate that the formation of PA clusters is a prerequisite for the formation and design of diatom cell walls.

Scanning electron micrograph of a Diatom (Thalassiosira pseudonana),
made by Prof. Manfred Sumper, Regensburg

  
     

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