First there was the Stone Age. Then came the Bronze Age. Recently the Information Age dawned. As the 21st century looms before us, we may well be looking into the "Nano Age."
Virtually every industry–from computers to cosmetics–is working to take advantage of nanotechnology. Nanotechnology refers to the ability to create and manipulate materials that are between 1 and 100 nanometers–or one-billionth of a meter–in size. A single hair is about 100,000 nanometers wide.
Nanomaterials can be found in products such as sunscreen, stain-resistant fabrics, and household appliances. And scientists are working on ways to incorporate nanomaterials into an even broader range of applications.
Unfortunately, a growing body of research suggests that nanoparticles may have an adverse effect on the environment. One of these studies was produced by a high school student from Chandler, Arizona. The results of her work indicate that nanoparticles can harm aquatic ecosystems.
Jingyuan Luo graduated from Chandler's Hamilton High School in 2007. She studied the effects of titanium dioxide nanoparticles on Chamydomonas reinhardtii, a type of green algae. Titanium dioxide nanoparticles are found in sunscreen, among other products.
"Research is really important at Hamilton High School," Luo says. She decided she wanted to get some hands-on experience, so she looked up faculty biographies on ASU's web site. She found Qiang Hu, a professor of applied biosciences with the Laboratory of Algae Research & Biotechnology (LARB) at ASU's Polytechnic Campus.
"Jingyuan contacted us about working on an environmental problem associated with nanomaterials," says Hu. "The decision to take on a high school student is not taken lightly. They require guidance and assistance, as well as supplies and materials."
When a student expresses interest, the researchers look at the student's grades, ask for a schedule and time commitment to the project, and request a research proposal that outlines the goals and plan of work.
"While the proposal is preliminary, it provides an indication of the level of thought that the student has put into the project. We also get a glimpse of the student's writing and organizational ability," explains Hu.
Luo had all the qualities of a good researcher.
"She is incredible. She was very mature for a high school student," says Sommerfeld.
She started doing work at the lab the summer after her sophomore year in 2005. She worked with Hu and postdoctoral researcher Jiangxiang Wang.
"They are some of the greatest people to work with," says Luo. "They are very intelligent, encouraging, and also very realistic. At 17, you have a lot of big ideas and they pull you back a little. They were very patient with me."
Luo exposed the algae to varying levels of titanium dioxide over five-day periods. She analyzed cell appearance and population growth. She also tested algal stress response at the genetic level.
She found that as titanium dioxide concentrations increased, the algal growth rate and cell populations decreased. Also, some stress genes were overexpressed in response to the presence of the nanoparticles.
Her results show that the nanoparticles had a large toxic effect on the algae. However, larger particles did not.
Because algae form the basis of most aquatic food chains, these particles could have an impact on entire aquatic ecosystems. Luo wanted to find out if they do.
"I always wanted to do bioaccumulation research. But due to time and knowledge constraints I wasn't able to at first," she says.
With a foundation in basic lab techniques, Luo was able to undertake a more complicated study in January 2007. This time she looked at the effects of two different nanoparticles–zinc oxide and carbon fullerenes–on both green algae and Daphnia magna, a water flea that feeds on the algae.
Nano-scale zinc oxides are used in sunscreens and scratch-resistant glass. Carbon fullerenes are also known as "buckyballs." They have potential applications in drug delivery systems, hydrogen fuel cells, superconductors, and cosmetics. But little is known about the effect these materials have on the environment, particularly in terms of bioaccumulation.
Bioaccumulation refers to an organism containing a higher concentration of a substance than the surrounding environment. This commonly happens when the substance works its way up the food chain by being eaten.
Luo conducted three tests. In two of the tests, she added nanoparticles directly to water containing either algae or fleas. In a third test she added nanoparticle-treated algae to fresh water for the fleas to eat.
She found that the nanoparticles were more toxic to the organisms than larger particles, and the zinc oxide was more toxic than the carbon. These results were greatest in the long-term, suggesting that future studies should examine the effects of nanoparticles over time.
Data on the bioaccumulation of nanomaterials was inconclusive, but suggests that the particles are transferred to the fleas from the algae.
Her work earned Luo a first place award in Environmental Science at the 2007 Intel International Science and Engineering Fair and a second place award in 2006. About 1,500 students from more than 40 nations compete in this annual event. She also received the National Stockholm Junior Water Prize for 2007, and represented the United States in Stockholm, Sweden in August.
Working under the supervision of the ASU scientists, Luo also gained a firsthand understanding of the research process.
"Once I started doing science research I really loved it. Yes, it's frustrating and sometimes you want to pull your hair out, but you sit back afterwards and you've accomplished something. I learned that I have to be a lot more patient. Sometimes things go wrong. You have to learn to adapt and adjust," she says.