Featured Research

from universities, journals, and other organizations

Nanotechnology In Environment: Citrate Appears To Control Buckyball Clumping But Environmental Concerns Remain

Date:
April 11, 2008
Source:
Virginia Tech
Summary:
Fullerenes, also fondly known as buckyballs, are showing an ugly side. It appears that the hydrophobic, or water hating, carbon molecules clump together in water, forming aggregates of thousands of molecules. And there are reports that these aggregates can be toxic. Now researchers have demonstrated that this behavior can be changed.

Fullerenes, also fondly known as buckyballs, are showing an ugly side. It appears that the hydrophobic, or water hating, carbon molecules clump together in water, forming aggregates of thousands of molecules. And there are reports that these aggregates can be toxic to microorganisms and even fish, should they escape from processing into surface water and ground water.
Credit: iStockphoto/Martin McCarthy

Fullerenes, also fondly known as buckyballs, are showing an ugly side. Since being discovered in 1985, the hollow carbon atoms have been adapted for nanotechnology and biomedical applications ranging from electronics to carriers of imaging materials.

It appears that the hydrophobic, or water hating, carbon molecules clump together in water, forming aggregates of thousands of molecules. And there are reports that these aggregates can be toxic to microorganisms and even fish, should they escape from processing into surface water and ground water.

Now researchers at Virginia Tech have demonstrated that this behavior can be changed by the addition of citric acid -- although the good news and bad news of this recent discovery has yet to be determined. They recently reported on their research to both environmental chemists and colloidal chemists at the American Chemical Society 235th national meeting.

"Our group and other research groups worldwide are examining what makes these fullerene aggregates tick and how they form," said Peter Vikesland, associate professor of civil and environmental engineering at Virginia Tech. "Once they clump, they don't settle out. People don't know why they remain suspended. And we don't really know how many molecules are in a clump. We use the term nC60 where N means some number that is extremely large."

What Vikesland's group has done that is different and novel is, instead of mixing the molecules with water, they have added citric acid, a naturally occurring and readily available acid. "The result is that instead of unstructured clumps, we get reproducible sphere-shaped aggregates," he said.

They discovered, for example, that in the presence of a little bit of acid, which emulates the environment in the case of an accidental release of fullerenes, the aggregates are similar to those formed in water alone. But when more acid is added, the diameter of the aggregates becomes smaller. "We want to understand the implications of this finding to the toxicity, movement, and fate of fullerenes in the environment."

Citric acid is well understood as a proxy for other kinds of organic acids, including those within cells. Some of the citrate-based spheres that Vikesland's group discovered are similar to what happens intercellularly when human cells are exposed to C60, he said. "We think citrate and other organic acids with a carboxyl group make C60 more water soluble."

Vikesland presented "Effects of small molecular weight acids on C60 aggregate formation and transport (ENVR 26)" to the Division of Environmental Chemistry on April 6. Authors of the paper are Vikesland, civil and environmental engineering Ph.D. student Xiaojun Chang of Luoyang, Henan, China, and master's degree student Laura K. Duncan of Augusta, Ga., and research assistant professor and TEM lab director Joerg R. Jinschek.

Future environmental research will be done with simulated subsurface environments using a sand column to determine how these acidified masses move in ground water.

Vikesland will present Chang's and his research about how C60 and citric acid interact to the Division of Colloid and Surface Chemistry on April 9 at the same conference. He will present the results of various imaging analysis, such as atomic force microscopy. "We have no answers but we have a hypothesis, still unproven, that there are weak interactions between citrate and individual carbon molecules that cause the spherical shape," Vikesland said.

The Vikesland group is exploring whether the C60-citrate interaction can be used to create reproducible shaped objects. Many fullerene-based products presently require solvents, which are then washed off. Unfortunately, the engineered fullerenes can retain solvents. Using citrate "is very green chemistry," Vikesland said. "There are no solvents. It is a cleaner way to produce these things. Citrate may be an alternative."

But there are challenges. "It's not a hard bond but a weak attractive force, which makes these spherical aggregates challenging to work with. At the present time we don't know how they will fall apart and what their products are," Vikesland said.

In the meantime, the solvent issue aside, the current rush to put fullerenes into materials may not be wise "because we don't understand what is going on," said Vikesland. "If you have a face cream with fullerenes as an antioxidant -- we don't know how they will react. There are many organic acids in the environment."

He concludes, "There are uncertainties. Everyone wants to prevent future problems."

Vikesland research is supported by the National Science Foundation. The project was also supported by the Institute for Critical Technology and Applied Science at Virginia Tech.


Story Source:

The above story is based on materials provided by Virginia Tech. Note: Materials may be edited for content and length.


Cite This Page:

Virginia Tech. "Nanotechnology In Environment: Citrate Appears To Control Buckyball Clumping But Environmental Concerns Remain." ScienceDaily. ScienceDaily, 11 April 2008. <www.sciencedaily.com/releases/2008/04/080408100542.htm>.
Virginia Tech. (2008, April 11). Nanotechnology In Environment: Citrate Appears To Control Buckyball Clumping But Environmental Concerns Remain. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2008/04/080408100542.htm
Virginia Tech. "Nanotechnology In Environment: Citrate Appears To Control Buckyball Clumping But Environmental Concerns Remain." ScienceDaily. www.sciencedaily.com/releases/2008/04/080408100542.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins