March 9, 2011

UW Nanotoxicology Center to look at nanoscale product safety

UW Health Sciences/UW Medicine

National Nanotechnology Initiative Society & Safety

UW Center for Nanotechnology

Terrance Kavanagh profile

These clean-up cells (macrophages) from a mouse have scarfed up millions of quantum dots, which fluoresce in red. The cell nuclei are stained blue./ Collin White image

These clean-up cells (macrophages) from a mouse have scarfed up millions of quantum dots, which fluoresce in red. The cell nuclei are stained blue./ Collin White image

Nano-sized materials are too small to be seen with the naked eye. A mouse cell, for example, measures approximately 20 microns. One micron equals 1,000 nanometers, which is how nanomaterials are measured.

“The novel size and size-dependent physical and chemical properties that make nanomaterials useful also make their interactions with biological systems difficult to anticipate and critically important to explore,” reports the National Institute of Environmental Health Sciences, whose recent funding initiative is part of a large-scale. cross-agency effort to support nanotechnology-related environmental, health, and safety research.  The UW is one of the institutions to receive a major nanotoxicology grant with $5.8 million in funding.

Because the nanotechnology field is relatively new, with different applications still in development, government agencies want to preemptively identify health and safety concerns.

The UW Nanotoxicology Center will develop standardized techniques, analytical tools, and mathematical models to assess and predict the toxicity and environmental impact of nanomaterials.

“We can use this information and the power of molecular engineering and biotechnology to build environmental health and safety into the nanoproducts of tomorrow,” explains Terrance Kavanagh,  center director. “They will have improved safety because they’ll be safe by design.” Kavanagh is professor of environmental and occupational health sciences in the UW School of Public Health.

Kavanagh and  the other center researchers will assess the toxicity of semiconductor quantum dots (Qdots), fluorescent nanoparticles that show great promise for medical imaging and optoelectronics, and for everyday use in LEDs and solar panels.

Qdots have raised concerns because they commonly contain heavy metals, such as cadmium or mercury. If Qdots were to break down and release those metals, their toxicity to humans might increase. Also, the kind of surface coating on Qdots can influence their interactions with cells.

“For instance, we know that nanoparticles with positive charges tend to be more toxic and more inflammatory than those with neutral charges,” explains Kavanagh.

Center researchers will use custom-designed Qdots, modified with respect to their core composition, surface charge, size, and method of manufacture. Researchers will examine the relationships between different physical and chemical properties and other quantitative measures of toxicity. For example, Qdots will be tested on cultured human and mouse cells to examine their ability to evoke an inflammatory response. They will also be tested using genetically defined mouse strains to better understand how Qdots are absorbed, distributed, and eliminated, and how they cause toxicity in the body.

Quantum dots, used with medical imaging, might show tumor sites more clearly, and may improve treatment by targeting cancer cells./Kristian Molhave illustration

Quantum dots, used with medical imaging, might show tumor sites more clearly, and may improve treatment by targeting cancer cells./Kristian Molhave illustration

“Once we determine which aspects are most highly associated with toxicity and the pathways involved, we’ll be able to recommend modifications that will make them safer,” explains Kavanagh.

Other lead researchers in the center include David Eaton, UW interim provost for research and professor of environmental and occupational heath sciences in the UW School of Public Health,  Elaine Faustman, and Michael Yost, both professors of  environmental and occupational health sciences; Xiaohu Gao, assistant professor of bioengineering in the College of Engineering and the School of Medicine; Francois Baneyx, the Charles W. H. Matthaie Professor Chemical Engineering and acting director, UW Center for Nanotechnology; and William Parks, professor of medicine, Division of Pulmonary and Critical Care Medicine and director, UW Center for Lung Biology.