Since the 18th-century scientists are studying diatoms, fascinated by their beauty and
diversity. Their nano- and micropatterned biosilica cell walls are outstanding examples of
biologically controlled mineral formation. Although the knowledge about diatom cell wall
formation increased over the last 60 years, the process is still far away from being completely
understood. Diatom cell walls exhibit highly interesting material properties, making them
appealing to material scientists. Due to those properties, diatom cell walls are on the brink of
becoming powerful tools in nanotechnology. However, the production of tailored silica
structures for nanotechnology requires a much better understanding of the processes and
components involved in cell wall morphogenesis. Recent studies set the focus on insoluble
organic matrices as important parts of this process, suggesting that they act as templates in
silica morphogenesis. Therefore, in this study, the occurrence of insoluble organic matrices
and their possible silica precipitation activity was analyzed in the three diatom species T.
pseudonana, T. oceanica and C. cryptica.
For all three species girdle band and valve derived insoluble organic matrices could be
identified. The extracted insoluble organic matrices exhibited structural features present in the
corresponding biosilica cell walls. The highest similarities were found in the valve derived
matrices of C. cryptica. Accessibility studies showed that the biosilica associated insoluble
organic matrices of T. pseudonana were only partially accessible, arguing for an entrapment
of insoluble organic matrices in the silica, rather than an attachment to the surface of the cell
wall. All examined insoluble organic matrices of the three species exhibited intrinsic silica
precipitation activity. The most intriguing structures were formed by the insoluble organic
matrices of C. cryptica, yielding a porous silica pattern. The addition of biosilica derived
soluble components or long-chain polyamines promoted this process and moreover lead to the
reconstitution of biosilica-like hierarchical silica pore patterns. The generated silica structures
were templated by the underlying structure of the insoluble organic matrix.
The result presented in this thesis make this the first study reporting the in vitro
generation of diatom biosilica-like hierarchical silica pore patterns using all natural cell wall
components. It supports the hypothesis of microplates acting as templates for biosilica
morphogenesis and introduces an interesting experimental setup for silica-based in vitro
studies on the mechanism of pore formation in diatoms.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:31116 |
| Date | 31 August 2018 |
| Creators | Pawolski, Damian |
| Contributors | Kröger, Nils, Brunner, Eike, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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