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 Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University

nachricht Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>