|Frank Noll1, Manfred Sumper2, and Norbert Hampp1
1Institute of Physical Chemistry, Department of Chemistry, Philipps-University, Hans-Meerwein-Str., D-35043 Marburg, Germany, and
Diatoms generate their cell walls by silica biomineralization. The cell walls are composed of silica and organic macromolecules, and show a complex microscopic structure. Analysis of this structure by different atomic force microscopy (AFM) techniques revealed an unexpected nanostructured granular surface. Silaffins, diatom proteins which are post-translationally modified with long-chain polyamines, as well as free propylamines of different chain lengths induce rapid precipitation of nanosized particles from silicic acid solutions in vitro. To better model the biological system, we reacted aqueous silicic acid solution with tripropyltetramine in CHCl3 in a biphasic system. As a result thin nano-structured silica layers were obtained which show a granular nanostructure very similar to that of the diatom cell walls. This finding may serve as a good model to study the mechanisms which lead to the nanostructure of the diatom cell walls.