A natural source of porous biosilica for nanotech applications: the diatoms microalgae

Several biological organisms, from some sea shells to butterflies, exhibit beautiful and sophisticated organs, developed during the evolution of each species, which properties are defined by their nanostructures. The marine diatoms are microscopic algae enclosed between two valves of hydrated amorphous silica. These intricate structures, called frustules, show quite symmetric patterns of micrometric and nanometric pores. Their strong similarity with man-made materials, such as synthetic zeolites, or porous silicon and alumina, suggests to exploit the physical properties of the frustules in nanotech applications. In this paper, we review the most relevant results achieved in our laboratory, and all over the world, about the discovery of surprising features that can be found in the characterization of these natural porous biosilica materials. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim