Diatom Nanostructured Biosilica

Bacillariophyceae (diatoms) is a unique class of unicellular microalgae of remarkable evolutionary success showing large diversity over a relatively short geologic timescale, leading to exceptional ecological roles in many aquatic ecosystems. Diatoms living cells build outstanding cell walls (frustules) made of amorphous hydrated silica featured with nanometric ultrastructure. Nowadays, diatoms are cultivated on different scales for many purposes and are involved in various industrial and commercial applications. This chapter overviews the wide applicability of diatoms nanostructured biosilica, especially in the fossil form (i.e. diatomaceous earth), as a functional additive and filler in various industries, such as fabrication of building materials, paints, agricultural products, rubbers, and pharmaceuticals. In addition, the chapter will shed light on the biorefinery approach of large-scale cultivated diatoms as a sustainable source of biosilica, besides extracting valuable metabolites. The extracted biosilica can facilitate the industrialization of the recently suggested biotechnological and biomedical applications utilizing diatoms silica as a green alternative to synthetic nanostructured materials.