Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UO’s molecular ’claws’ trap arsenic atoms

16.11.2004


This model shows the x-ray crystal structure of the most stable self-assembled arsenic cluster discovered so far by Jake Vickaryous and Darren Johnson at the University of Oregon. The image reveals the sequestered environment of the arsenic atoms, shown in purple, after they’ve been trapped by molecules composed of carbon, sulfur and hydrogen atoms (shown in gray, yellow and white, respectively). These molecules are claw-like structures that grab onto the arsenic atoms, preventing them from forming bonds with other types of molecules.


Chemists at the University of Oregon have hit upon a way to build a molecular "claw" that grabs onto arsenic and sequesters it.

The discovery is published in the Nov. 5 issue of Angewandte Chemie International Edition, a premier journal in the field of chemistry.

Since the article was written, the UO team has developed additional ways of capturing arsenic so that it cannot bond with other substances in a laboratory setting, according to Darren Johnson, an assistant professor of chemistry specializing in supramolecular and materials chemistry. Johnson, who joined the UO faculty in 2003, is also affiliated with the Oregon Nanoscience and Microtechologies Institute (ONAMI).



The molecules developed by Johnson and one of his graduate students, Jake Vickaryous of Portland, are known as a chelators (pronounced "kee-lay-tor", from the Greek chele, meaning "crab claw"). A chelator’s molecular configuration and binding sites enable it to trap and immobilize a heavy metal atom. In this case, a sulfur-based molecule was synthesized. In the presence of a toxic form of arsenic, three of these molecules bond with two arsenic atoms to create a triangular, pyramid-like molecular structure. "By improving our understanding of these chemical interactions, we hope to develop more effective remediation agents--molecules that can do the work of rendering arsenic harmless," Johnson says.

Although they’ve demonstrated their new molecule can encapsulate arsenic in a laboratory setting, Johnson says, the challenge of treating poisoned individuals remains. The next step is to verify that the new molecule can render arsenic harmless without creating new problems in the human body. "We’re now trying to prove that our molecule wants arsenic more than things in your body want arsenic," says Johnson.

Numerous studies have linked consumption of minute amounts of arsenic in drinking water with higher incidences of lung, bladder, kidney and skin cancers, among other potentially fatal conditions. Arsenic is naturally abundant in the Earth’s crust, and arsenic compounds are involved in some industrial applications.

The U.S. Environmental Protection Agency, in compliance with the Safe Water Drinking Act, currently requires that public water systems contain arsenic concentrations of less than 50 parts per billion (ppb). In 2006, this level is to be reduced to 10 ppb. This stricter standard has been endorsed by the World Health Organization since 1993.

Developing countries face serious problems due to arsenic-laced water sources but arsenic also is a problem in the United States. Roughly 10 percent of U.S. groundwater contains arsenic concentrations above 10 ppb. In Johnson’s backyard, Oregon’s bucolic Willamette Valley, more than 20 percent of wells have arsenic levels greater than 10 ppb. Of these, almost 10 percent exceed 50 ppb.

While they used computer-generated molecular models to predict many of the features they observed, Johnson says, the project also yielded some unexpected, and pleasant, surprises. "We have stumbled upon some surprisingly stable self-assembled arsenic complexes. Someday, this approach may provide better agents for sensing and removing arsenic from the environment as well as the body," Johnson says.

Self-assembly refers to the ability of molecules to naturally join themselves together into larger structures due to the manners in which their geometric and binding structures complement one another. This feature, which is like a puzzle that puts itself together, is quite promising because it creates a final product that is more stable than the sum of its parts, Johnson explains.

In addition to modeled predictions, the structure of the molecule was confirmed using two primary methods. Nuclear magnetic resonance (NMR) spectroscopy uses the same principles that are the basis for magnetic resonance imaging (MRI), a commonly used medical scan of human tissue. The sample molecules are placed in a powerful magnetic field and are stimulated by specific patterns of radio waves. The patterns of energy that the molecules then release are interpreted to determine composition and structure. Another technique, X-ray diffraction, analyzes the scattering pattern of x-rays directed at a substance in order to characterize its atomic-scale structure.

Johnson, a UO assistant professor of chemistry, supervises the work of W. Jake Vickaryous (pronounced like the word "vicarious"), the UO doctoral degree candidate in chemistry who synthesized the molecule and is the lead author for the Angewandte Chemie article. Rainer Herges, the article’s third co-author, is a professor at the Institut for Organische Chemie in Kiel, Germany, who produced the computer modeling studies for the project.

This phase of their work was funded by a UO research grant. In September, Vickaryous was awarded a National Science Foundation fellowship to support doctoral training at the interface of chemistry and physics. He will study new materials for electronics and optics through control of nanoscale structure.

Melody Ward Leslie | EurekAlert!
Further information:
http://www.uoregon.edu

More articles from Life Sciences:

nachricht Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>