Silicification and biosilicification: The role of macromolecules in bioinspired silica synthesis

Diatoms, sponges and grasses are all known to produce ornate biogenic silica structures under ambient conditions. Some aspects of the molecular mechanism controlling biosilicification have recently been elucidated. The entrapment of the catalyzing/templating/scaffolding biomacromolecules enables them to be recovered by selective dissolution of biosilica. The proteins extracted from the diatom Cylindrotheca fusiformis (silaffins) and the sponge Tethya aurantia (silicateins) have been shown to precipitate silica from silica precursors in vitro. The identification of synthetic macromolecules that can act as catalysts/templates/scaffolds for silica formation gives exciting possibilities for bioinspired silica synthesis. Herein, the role of various synthetic (bio)macromolecules in silicification is studied. Attempts have also been made to understand the mechanism(s) governing (bio)macromolecule mediated (bio)silicification. Furthermore, the results and the understanding gained from various synthetic systems are used to demonstrate the potential of such bioinspired routes to develop new materials.