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Silver Nanoparticles are more common than we thought!

If you've used silverware and worn copper jewelry in a warm, humid room, you've been in a perfect storm in which nanoparticles were dropped into the environment, say scientists at the University of Oregon.

Ever since nanotechnology emerged, researchers, regulators and the public have been concerned about the potential toxicity of the residual materials from nano-sized products that that might threaten human health by way of environmental exposure.

Now, with the help of high-powered transmission electron microscopy, chemists in the UO's Materials Science Institute, working in collaboration with UO technology spinoff Dune Sciences Inc., captured never-before-seen views miniscule metal nanoparticles naturally being created by silver articles such as wire, jewelry and eating utensils as they come in contact with surfaces. Turns out nanoparticles may have been in contact with humans for a long, long time.

In fact, researchers found, nanoparticles deposited on the surface of their testing grids began to transform in size, shape and particle populations within a few hours, especially under certain environmental conditions.

"Our findings show that 'size' may not be static, especially when particles are on surfaces. For this reason, we believe that environmental health and safety concerns should not be defined -- or regulated -- based upon size," said James E. Hutchison,  who holds the Lokey-Harrington Chair in Chemistry. "The generation of nanoparticles from objects that humans have contacted for millennia suggests that humans have been exposed to these nanoparticles throughout time. Rather than raise concern, I think this suggests that we would have already linked exposure to these materials to health hazards if there were any."

Because copper behaved similarly, the researchers theorize that their findings represent a general phenomenon for metals readily oxidized and reduced under certain environmental conditions. "These findings," they wrote, "challenge conventional thinking about nanoparticle reactivity and imply that the production of new nanoparticles is an intrinsic property of the material that is now strongly size dependent."

The research -- detailed in a paper placed online in advance of regular publication in the American Chemistry Society's journal ACS Nano -- was done using transmission electron microscopes in the Center for Advanced Materials Characterization in Oregon.  CAMCOR is located in the underground Lorry I. Lokey Laboratories at the UO.

In their paper, Hutchison and colleagues describe the system they devised, which they say allows for accurate studies of nanoparticle activity in a wide range of controlled environmental conditions. The platform, they report, permits the direct observation of the formation of small nanoparticles in the vicinity of tethered nanoparticles, "providing insight in the material dynamics behind this reactivity."

Based on multiple studies under varying conditions, researchers found that exposure to humid air, water and light drove the formation of new nanoparticles regardless of size. Any potential federal regulatory policies, they concluded, should allow for the presence of background levels of nanoparticles and their dynamic behavior in the environment.

While not addressed directly, Hutchison said, the naturally occurring and spontaneous activity seen in the research suggests that exposure to toxic metal ions, for example, might not be reduced simply by using larger materials in the presence of living tissue or organisms.

Co-authors with Hutchison on the paper were Richard D. Glover, a doctoral student in chemistry, and John M. Miller, a research associate. Both study in Hutchison's lab. Hutchison and Miller were co-founders of Dune Sciences Inc., a Eugene-based company that specializes in products and services geared toward the development and commercialization of nano-enabled products. Miller currently is the company's chief executive officer; Hutchison is chief science officer.

The U.S. Air Force Research Laboratory and W.M. Keck Foundation supported the research. Glover's participation also was funded by the National Science Foundation's STEM (science, technology, engineering, mathematics) Fellows in K-12 Education Program.

About the University of Oregon

The University of Oregon is among the 108 institutions chosen from 4,633 U.S. universities for top-tier designation of "Very High Research Activity" in the 2010 Carnegie Classification of Institutions of Higher Education. The UO also is one of two Pacific Northwest members of the Association of American Universities.

Contact: Jim Barlow, director of science and research communications, 541-346-3481, jebarlow@uoregon.edu

Source: James E. Hutchison, Lokey-Harrington Chair in Chemistry, hutch@uoregon.edu. (NOTE: Hutchison currently is on sabbatical. To arrange an interview, contact him by email or through the media contact above).

Links:

Hutchison website: http://chemistry.uoregon.edu/fac.html?hutchison

Dune Sciences Inc: http://www.dunesciences.com/

Nanowiki: Nanowiki

 

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