Small particles affect the life of cells
Many of the products we buy — sunscreen, stain- and odor-resistant clothing, fuel additives, sports equipment — contain nanoparticles that have been designed for a purpose. These materials (about 100,000 times smaller than the width of a human hair) can block sunlight, prevent microbial growth, lubricate surfaces and confer tensile strength.
However, in some cases, they can also disrupt biological processes. That possibility keeps Stacey Harper (Environmental and Molecular Toxicology; Chemical, Biological and Environmental Engineering) coming to her lab every day. The assistant professor and her research team have pioneered new methods to find out how nanoparticles affect life at the cellular level and what those impacts might mean for ecosystems and human health.
With funding from the National Science Foundation, they have created microcosms, simplified aquaria composed of algae, bacteria, zooplankton and fish. By adding nanoparticles, they can detect changes that would not be apparent with one organism alone. Silver, zinc oxide and titanium dioxide nanoparticles are under scrutiny “because they are the most prevalent ones in aquatic ecosystems,” says Harper.
Also relevant to aquatic systems are nano-based pesticides. In a project funded by the U.S. Department of Agriculture, Harper and her team are determining how the nanoparticles added to these chemicals alter their movement through soil and water. It’s possible, she adds, that their bioavailability could change as well.
Biological effects may stem from shape as well as chemistry. In a project funded by the National Institutes of Health, Harper’s team is working with Oregon State chemists and wood scientists to determine how “prickly” forms of gold-based particles and nanocellulose affect living systems
Harper has tested hundreds of nanoparticles and found less than 20 that appear to be toxic at realistic concentrations. As for sunscreen, a study by George Tuttle, a master’s student, compared chemical-based products to those that use nanoparticles as a barrier to sunlight. “We found that they (nanoparticles) were way less toxic” than the chemical formulations, Harper says