Seminar: Geoffrey Ozin, University of Toronto
Professor Geoffrey Ozin of University of Toronto presents a seminar in Chemical & Biomolecular Engineering, "Green Nanochemistry."
Nanomaterials prepared by nanochemistry approaches are poly-dispersions with a characteristic nanoparticle size distribution. This means that nanoparticle properties measured and reported to date, whether chemical, physical or biological, refer to an ensemble average. This makes the quantitative evaluation of their toxicity, whether in vivo or in vitro, precarious at best as one never can be absolutely sure whether it is a specific size, shape or surface property of a nanoparticle or a certain group of nanoparticles or every nanoparticle in an ensemble that is responsible for a positive toxicity test result and may therefore pose a health and safety hazard to researchers, manufacturers and consumers. The same uncertainty applies to the behavior, fate, bioavailabilty and effects of nanoparticles that escape into the environment.
Currently many Fortune 500 companies and about 1500 spin-off companies around the world are involved in nano R&D and there are now about 600 nano-based products on the market. It is ironic that while nanoparticles are gainfully exploited in nanoscience and nanotechnology and celebrated for their exquisite size, shape and surface tunable properties, it is precisely these attributes that are potentially problematic in health and safety matters when trying to quantify the toxicity of a poly-dispersion of nanoparticles where it is impossible to decide whether it is the size, shape or surface of all, some, one or none of these nanoparticles that we have to be concerned about.
With this in mind it makes sense to intensify the global research effort of the nanochemistry community on the synthesis and study of nanoparticles that are purportedly “green. The newest collection of “green” nanoparticles to have caught my attention recently and which seem to be most promising candidates in this context are based on C, Si, Ge, Bi whose appealing energy storage, optical, optoelectronic, photonic and biomedical attributes are gaining much attention.
In this lecture I will describe our recent work on the synthesis and size separation of poly-dispersions of colloidally stable silicon nanocrystals into mono-dispersions, the measurement of representative size dependent properties, and steps towards their integration into optoelectronic and biomedical devices.
So when contemplating growing your nano materials garden for pleasure or profit, think “green”!