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Duo create molecular trap for arsenic.

Byline: Greg Bolt The Register-Guard

University of Oregon researchers have come up with a kind of molecular prison that traps arsenic, a discovery that has the potential to lock up one of the most potent environmental toxins people face.

It remains to be seen if the new molecule can be further developed for use in cleaning up contaminated water or treating victims of arsenic poisoning. But if it can, it could be a powerful new tool for countering a naturally occurring poison that contaminates water supplies around the globe.

UO chemistry professor Darren Johnson and graduate student Jake Vickaryous came up with the new molecule while on something of a scientific fishing expedition. A new faculty member who came to the UO in June 2003, Johnson works in supramolecular chemistry - the study of how molecules interact with one another - and thought there might be some new work to be done with some of the more toxic metallic elements, the ones found in a rough neighborhood of the chart of elements.

"Things like arsenic, lead, mercury and bismuth," Johnson said. "The ones down in the bottom right corner of the periodic table."

Typically, this kind of basic science can take years to produce results. But Johnson and Vickaryous stumbled on something in just a few months, a molecule made of sulphur and carbon that hooked onto arsenic the way a crab goes after dinner.

Three sulphur-based molecules join with two arsenic atoms to form a kind of pyramid-shaped molecule that's more stable than the sulphur molecule alone. Once locked into the molecule - which Johnson describes as a "molecular claw" - the arsenic seems quite happy to stay where it is and not combine with any other molecules.

What that means is that, if the molecule can be developed further, it might offer a way to neutralize arsenic. If the molecule is so stable that it won't link up with any other molecules, it could effectively remove arsenic from human tissue or offer a way to make arsenic-tainted wells safe for drinking water.

"One thing this could potentially do is provide some new environmental remediation and sensing tools," Johnson said.

Arsenic is considered a potent environmental toxin linked to a variety of cancers and other serious diseases. It occurs naturally as a mineral and poses a threat to wells and groundwater supplies worldwide.

The federal government currently requires that public water systems have no more than 50 parts per billion of lead and will reduce that to 10 parts per billion in 2006. About 10 percent of the groundwater in the United States has arsenic concentrations above 10 ppb, although 20 percent of the wells in the Willamette Valley exceed that level.

Even minute amounts of arsenic in the human body are potentially damaging. The research might eventually lead to a treatment for arsenic poisoning, but that kind of development is a lot further down the road; right now, the molecule can only be created in a highly toxic, arsenic-based solvent.

Johnson and Vickaryous now will try to develop a water-soluble version of the molecule, hopefully one that's harmless to humans. They also have to make sure their molecule isn't a schemer that will abandon its arsenic atom the first time some other metallic element wanders past.

"We need to give the molecule a lot of different metallic molecules and see if it always chooses arsenic," Johnson said. "We'd love to make something nontoxic that we could give to people that would clear arsenic out of their body, or out of the environment."

It also may be possible to use the same type of molecular design strategy to create molecular claws that neutralize other toxic metals, such as lead and mercury. Johnson is hopeful that similar molecular jails can be built for those hazards as well.

The research recently was published in a prominent chemistry journal. Johnson said it was a pleasant surprise to come across something so promising so soon after starting at the UO.

"The exciting part is having something happen so soon," he said. "It's just fun to have a research direction early on that could open quite a few doors."

CAPTION(S):

Darren Johnson, a University of Oregon associate professor of chemistry, and one of his graduate students, Jake Vickaryous, have developed a molecule of sulphur and carbon that binds to arsenic and could someday be used to neutralize the poison in the environment and in the human body.
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Title Annotation:Higher Education; Scientists someday might be able to use it to remove the poison from drinking water and human bodies
Publication:The Register-Guard (Eugene, OR)
Date:Dec 1, 2004
Words:740
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