Vimentin intermediate filaments as a template for silica nanotube preparation.

Organic compounds are used as templates to regulate the morphology of inorganic nanostructures. In the present study, we used intermediate filaments (IFs), the major cytoskeleton component of most eukaryotic cells, as a template for hollow silica nanotube preparation. Sol-gel polymerization of tetraethoxysilane proceeded preferentially on the surface of IFs assembled from vimentin protein in vitro, resulting in silica-coated fibres. After removing IFs by calcination, electron microscopy revealed hollow silica nanotubes several micrometers long, with outer diameters of 35-55 nm and an average inner diameter of 10 nm (comparable to that of IFs). Furthermore, the silica nanotubes exhibited a gnarled surface structure with an 18-26 nm repeating pattern (comparable to the 21-nm beading pattern along IFs). Thus, the characteristic morphology of IFs were well replicated into hollow silica nanotubes, suggesting that IFs maybe useful as an organic template.