Aqueous chemistry and biochemistry of silicon

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The long-term objective of my research program is to explore the fundamental chemistry and biochemistry of aqueous silicon (Si), and to apply that knowledge for the advancement of material science, agriculture, health and the environment. Si is the second-most abundant element in the earth's crust after oxygen, and the global Si cycle - a complex interaction of geological, chemical and biological processes - occurs largely in the aqueous phase. The element is nutritionally essential for half the ocean's biomass and is therefore an important factor in climate regulation. It is also beneficial for most higher lifeforms; in mammals, for example, dietary Si supports connective tissue health and regulation of immune and inflammatory response. Very little is known about silicon's bioactivity at the molecular level, however. Because aqueous Si chemistry underpins most modern information (semiconductors), construction (concrete) and chemical manufacturing (catalysts) infrastructure, it plainly has great economic importance as well.    Over the next five years we will probe mechanisms of mineral formation, e.g., investigating how metal ions affect structure, equilibria and chemical exchange kinetics of aqueous silicates. We will also continue research of silicate-carbohydrate chemistry which, since its discovery by my group several years ago, appears increasingly to be the chemical agency behind Si biofunctionality. Evidence has emerged to suggest that it may even have played a pivotal role in the origin of life. As well, we are exploiting this chemistry to create additives (derived from forest product waste) that improve mechanical and chemical performance of concrete while dramatically reducing its carbon footprint. Biological studies will be expedited by the availability of cyclotron-produced silicon-31. This short-lived radioisotope will be used to directly monitor uptake, translocation and bioconversion of Si-containing molecules in both plants and animals. We will also investigate the ability of Si to serve as a cross-linking agent (in, e.g., mammalian connective tissue & plant cell walls) or as an inhibitor of certain biochemical signaling pathways. Additionally, we will examine the immunostimulatory role of silica nano-particles in mammals and the fire-propagating ability of silica micro-particles in plants.