Medical News From The American Chemical Society

Main Category: Biology / Biochemistry
Also Included In: MRSA / Drug Resistance;  Infectious Diseases / Bacteria / Viruses;  Neurology / Neuroscience
Article Date: 07 Sep 2007 - 4:00 PST

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Tiny carbon nanotubes show big germ-fighting potential

In nanoscience's version of a David-and-Goliath story, scientists in Connecticut are reporting the first direct evidence that carbon nanotubes have powerful antimicrobial activity, a discovery that could help fight the growing problem of antibiotic resistant infections. Their research on so-called single-walled carbon nanotubes (SWNTs) published in the ACS' Langmuir, a bi-weekly journal.

Menachem Elimelech and colleagues point out that past research on the toxicity of SWNTs has focused on their adverse human and environmental effects. These microscopic cylinders of carbon -- thousands of times smaller than a human hair -- are one of the most promising raw materials for commercial and industrial applications of nanotechnology in the 21st century. Their potential uses range from biosensors to new drug delivery systems.

"Surprisingly, however, no published studies exist on the direct interaction of SWNTs with microbes," their report states. "Our experiments provide the first direct evidence that highly purified SWNTs exhibit strong antimicrobial activity and indicate that severe cell membrane damage by direct contact with SWNTs is the likely mechanism responsible for the toxicity to model bacteria. These observations point to the potential use of SWNTs as building blocks for antimicrobial materials."

"Single-Walled Carbon Nanotubes Exhibit Strong Antimicrobial Activity"

CONTACT:
Menachem Elimelech, Ph.D.
Yale University
New Haven, CT

Toward improved drug-delivery: Coating gives nanowires easy access to cells

Scientists in Idaho and Korea are reporting development of a protein coating that may turn nanowires into a new drug delivery system that could allow use of lower doses of medicine that are less harmful to normal cells. In a report in the ACS' Nano Letters, a monthly journal, they describe use of the coating to enable silica nanowires to enter cultured human cells and deliver a lethal dose of toxin.

Gregory Bohach, David McIlroy, Carolyn Hovde, and their colleagues point that nanowires and other nanomaterials (NMs), which are 50,000 times smaller in diameter than a human hair, have great potential as new drug delivery systems. NMs may penetrate tumors more easily, for instance, and could be coated with antibodies or other materials that home in on target cells while sparing normal cells.

One roadblock, however, involves finding ways to enable NMs to easily penetrate cells. The researchers report nanowires coated with the protein fibronectin penetrate cells more easily than uncoated nanowires. In experiments with human and animal cells, they showed that coated nanowires can enter and deliver a toxic agent called StxA1 that killed the cells. "This indicates that nanowires can carry StxA1 and potentially other toxic or therapeutic agents into cells," the researchers said.

"Nanowire-Based Delivery of Escherichia coli O157 Shiga Toxin 1 A Subunit into Human and Bovine Cells"

CONTACT:
Gregory A. Bohach, Ph.D.
University of Idaho
Moscow, Idaho 83844

Memory enhancement drugs show promise but face growing scrutiny

In our aging society, with an increased urgency to develop new compounds that target serious illnesses like Alzheimer's and Parkinson's disease, memory enhancement drugs are becoming big business. But these same drugs are also creating a growing ethical controversy over their potential off-label uses, such as taking these drugs as "performance enhancers" to gain a competitive advantage in the workplace. These issues, along with the biochemistry of memory, are explored in an article (http://pubs.acs.org/cen/coverstory/85/8536cover.html) in Chemical & Engineering News (C&EN), ACS' weekly newsmagazine.

Right now, there are only a handful of memory-enhancing drugs on the market. In the C&EN cover story, senior editor Sophie L. Rovner describes work at several companies, from small start-ups to pharmaceutical giants, that are developing and testing a variety of memory enhancing products that show promise for the treatment of Alzheimer's, Parkinson's, stroke and schizophrenia. In the continuing search for better drugs, even familiar compounds such as nicotine and coffee are being explored for their potential memory-enhancing effects, Rovner notes.

Despite their promise, there's growing regulatory and ethical concern about the use of such drugs for non-medical purposes. This includes using memory-enhancing compounds as stimulants to gain a competitive edge in the workplace or even on exams, which could result in unfair advantages over people who do not use the drugs. The possibility of off-label or recreational uses of these drugs could ultimately limit their wider acceptance, the article suggests. For better or for worse, memory-enhancing drugs are poised to play a bigger role in the future.

"Memory Enhancement: Several companies are developing compounds that improve memory, but ethical issues abound"

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Article adapted by Medical News Today from original press release.
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The American Chemical Society -- the world's largest scientific society -- is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

Source: Michael Woods
American Chemical Society