The Polyamine Silica System: A Biomimetic Model for the Biomineralization of Silica

From laboratory studies and industrial applications, it has long been known that polyamines influence the condensation process of silica. Interestingly, it has been found that polyamines are also involved in the formation of the silica exoskeletons of diatoms. This biomineralization process yields intricately patterned silica shells. Thus, a large variety of polyamines have been studied with regard to their influence on the kinetics of silica condensation, and with regard to possible mechanisms producing the patterns, among them polymers as polylysine and polyallylamine. In this chapter these studies are reviewed, with emphasis placed on the behavior of poly(ethyleneimine) and poly(propyleneimine) in silica solutions undergoing a condensation reaction. These amines have an architecture which closely resembles that of the polyamines occurring in diatoms. Therefore, model studies involving these synthetic polyamines can provide valuable additional information on the biosilicification process in diatoms.