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Nano Research Pioneer Speaks at NIEHS

By Eddy Ball
February 2009

When Walker introduced the speaker, he noted that the new Center for the Environmental Implications of NanoTechnology headed by Wiesner will "increase the amount of research going on in the area in terms of nanotechnology." (Photo courtesy of Steve McCaw)

Wiesner introduced the central paradox of his research early in the talk. "Unfortunately, the things that make nanomaterials so interesting to us," he explained, "are precisely the factors that make them potentially dangerous." (Photo courtesy of Steve McCaw)

Duke University nanomaterials specialist Mark R. Wiesner, Ph.D., made his first visit to NIEHS on January 9 as a guest lecturer in the Frontiers of Environmental Sciences series. His talk, "Reducing Uncertainty Surrounding Environmental Risks of Nanomaterials: Assessing Transport and Transformation," kicked off the 2009 series, which was hosted by National Toxicology Program (NTP) Deputy Program Director for Science Nigel Walker, Ph.D.

Wiesner is a professor of Civil and Environmental Engineering in Duke's Pratt School of Engineering. He also serves as director of the university's new Center for the Environmental Implications of NanoTechnology (CEINT) ( Exit NIEHS - part of a consortium that includes Carnegie Mellow University, Howard University and Virginia Polytechnic Institute and State University and works closely with other domestic collaborators and international partners in Europe, China and South America.

Wiesner devoted the first half of his talk to describing the multi-faceted research planned or already underway at CEINT in its three "theme" and three core areas. These areas range from nanomaterial transport and transformation in laboratory systems to modeling complex and dynamic interactions of nanomaterials with the environment to assess risk.

The center is studying natural, incidental and manufactured nanomaterials and creating mesocosms in Duke Forest to more accurately simulate real-life environments for studying the impact of nanomaterials' life cycle on ecosystems. The interdisciplinary research teams are also trying to estimate what future production levels may be as a basis for better understanding potential levels of exposure.

"We tend to do what I call ‘bubble-up research,'" Wiesner observed. "We start with very simple systems, and we try to build up to the complex - adding more and more solutes and organics that can interact with the nanomaterials, adding an organism that takes those materials up, then looking at multiple organisms and transfers through trophic levels all the way up to try to build a whole ecosystem, and looking for mechanisms all along the way."

Although the center is funded by the National Science Foundation and U. S. Environmental Protection Agency, researchers there are also collaborating with NIEHS grantees. These include Duke University Superfund Basic Research Center Director Rich Di Giulio, Ph.D., and Andre Nel, M.D., Ph.D., chief of the new Division of NanoMedicine at the University of California Los Angeles.

For the second part of his talk, Wiesner turned to work in his own lab on nanomaterial transformations with a focus on the aggregation of nanomaterials and factors that control their mobility and transport. Nanomaterials present researchers with what Wiesner described as "pervasive high levels of uncertainty" and issues of uniformity as investigators strive to understand how their novel qualities of size, shape, adsorptive surface area, aggregation kinetics and other qualities - even the way they are manufactured and integrated into finished products - may impact their behavior and, ultimately, any effect they could have on human health.

"We're very interested in how particles approach each other, contact and stick," Wiesner continued. "It affects the rates of rate of aggregation, it affects the rate of settling, and it also affects, as it turns out, the reactivity." Aggregation patterns, Wiesner reasoned, are likely responsible for the apparent paradox involving reactive oxygen species production by tightly packed aggregates of molecules of a compound and single molecules of the same compound.

Nanomaterials, Wiesner emphasized several times in the talk, present researchers with many variables that need to be resolved before the apparent safety of the materials in the environment, observed so far, can be properly assessed. "When we start out with the materials in the bottle and put them in nature," Wiesner concluded, "the characteristics of those materials are going to be very different than they would have been initially, and we need to account for that difference when we do eco-tox studies."

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