Nanomaterials & the Environment
Some of the world’s most innovative environmental research is being conducted at the University of Notre Dame’s Center for Nano Science and Technology. Here, multidisciplinary teams of engineers, geologists, chemists and biologists are studying biomaterials at the nanoscale – structures that are 1 to 100 nanometers wide. (To provide a sense of scale, a nanometer is a millionth of a millimeter long.) Their nano research involves the impact of certain materials, especially minerals, on human health and the environment.
"Mineral properties are far more complex than scientists originally thought," says Patricia Maurice, professor of civil engineering and geological sciences. "We have demonstrated that mineral nanoparticles behave very differently with respect to environmental reactions and processes, compared to larger materials of the same mineral composition."
For example, Maurice is exploring how iron oxides and hydroxides at particle sizes less than 10 nanometers may behave differently in the environment, including how they bind pollutants or their availability to microorganisms, such as iron—consuming bacteria.
Maurice’s pioneering work has shown that particle size impacts "bioavailability" – the way certain chemicals are taken up by living organisms. In particular, Maurice has demonstrated that the degree of bioavailability of hematite (iron oxide) to soil bacteria is directly related to particle size. Particles dissolve more rapidly and release nutrient iron more quickly when they are 10 nanometers or less in size, compared to particles a few tens of nanometers larger.
"The data suggest that enhanced bioavailability may be related to mechanisms that depend on cell—nanomineral proximity," says Maurice. "Cell—surface—associated molecules and/or the ability to chemically reduce nanoparticles at the cell—wall interface may also be important. The observed increase in bioavailability has important implications for other fields, including engineered nanoparticles for biomedical applications."
Maurice is also exploring how nanoparticles affect the environment and human health. For example, are toxins and pollutants more easily taken up at the nanoscale and, therefore, more potentially harmful to the body? What are the impacts of natural and synthetic nanomaterials on the environment? How mobile are they in the water supply and in water treatment? How might exposure to sunlight affect their properties and reactivity? How do atmospheric nanoparticles affect the earth’s energy budget and climate change?
"There is a whole world of nanoscale materials and processes we hardly understand, and it’s a wide—open field for exploration," says Maurice. "We need to develop a new theoretical understanding, and the math that goes with it, for nanoscale environmental processes. The toxicology of nanoparticles and their transport in environmental systems is a top concern. The nano—revolution has tremendous promise, but is also producing whole new classes of potential pollutants. We need to be wise in our use of this technology and the release of nanomaterials into the environment."