ASU Studies Impact of Nanoparticles on Aquatic Organisms

Sun screen - you can't live without it in the Southwest. But the very product that is protecting human skin from harmful solar rays could be wreaking havoc on the environment because of one ingredient.

Researchers at Arizona State University have been studying the impact of nanoparticles, such as titanium dioxide/oxide (TiO2), which is found in sunscreen and many other products, on aquatic organisms. With so much to study in the way of nanoparticles, they agreed to enlist the help of a rather curious high school student.

Jingyuan Luo, a Hamilton High School senior, volunteered her time during her junior year because of her love for research. "I wanted to do something that I did not have to do for a grade," said Luo. "I wanted to do it for me, because research is somewhat of a hobby for me."

Luo initially contacted researchers at The Biodesign Institute at Arizona State University, but because of her interest, she was forwarded to Drs. Qiang Hu and Milton Sommerfeld. "She contacted us and we liked what we saw in her resume and ideas presented," said Hu.

After some direction, she studied the effect of TiO2 on one species of green algae in Hu and Sommerfeld's Laboratory for Algae Research & Biotechnology (LARB) on the Polytechnic campus. Her work is part of the larger study being conducted by both, looking at the potential toxicity and bioaccumulation of nanomaterials in the aquatic ecosystem.

"Micro-organisms are a good indicator of toxins in the water," said Hu. "That's why algae are used."

"If the algae are negatively impacted by high levels of the nanoparticle, then it could impact the entire food chain, and it would be ecologically significant," said Sommerfeld.

With her post-doctoral mentor Jiangxiang Wang, the two studied varying levels and size of TiO2 on Chamydomonas reinhardtii (a green alga) over five-day periods, tracking the stress based on cell appearance and population growth. Several tests were conducted to examine stress response at the gene level and to gain a better understanding of the effects of nanoparticles on the alga.

Their findings showed that the higher concentration of TiO2 nanoparticles, the slower the growth rate and the smaller the cell population. Furthermore, some stress genes were over expressed in response to the presence of nanoparticles. This demonstrates that nanomaterials can be toxic to algae, indicating a potential negative influence on the aquatic food chain. It also showed that regular or larger-sized particles are not as toxic to algae as the nanoparticles. The reason for this response is not clear and represents an area for further study.

While most teenagers Luo's age want to spend as much time with friends as possible, she says her experience in the lab was worth missing social events. "I was able to apply what I learned from my advanced placement chemistry and biology classes, and the research took me out of my comfort level," said Luo. "I also learned how to use lab equipment without killing myself. And it also helped me determine which area of science I will focus on in college."

The research also has helped her succeed in taking first place in local and regional fairs and second place at the Intel International Science and Engineering Fair as well. She also received the Governor's Arizona Young Innovator of the Year award in 2006. In addition to her interest in science, she is a member of the speech and debate team, the Model United Nations, National Honor Society and We the People. In her spare time, she volunteers at the Carl T. Hayden Veterans Affairs Medical Center.

"I wanted to try a lot of different things in high school, so by the time I was ready to graduate, I would have a better idea of what I wanted to study in college," said Luo. "I'm still unsure of my major but plan to continue research in the nano sciences."

This spring, Luo is working at the LARB on the bioaccumulation of nanomaterials using green alga and extending it to daphnia. And that's not all she has planned before she graduates in May.

"I also will be working at The Biodesign Institute once I am ready to study zebrafish, so I can understand how nanomaterials affect an aquatic food chain and if an increase in concentration of an element or compound occurs as it moves up the food chain," added Luo.

http://www.asu.edu/

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