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YALE UNIVERSITY: Yale Scientists Use Nanotechnology to Fight E. coli; Menachem Elimelech Menachem Elimelech
[September 03, 2007]

YALE UNIVERSITY: Yale Scientists Use Nanotechnology to Fight E. coli; Menachem Elimelech Menachem Elimelech


(M2 PressWIRE Via Thomson Dialog NewsEdge)
RDATE:28082007

New Haven, Conn. -- Single-walled carbon nanotubes (SWCNTs) can kill
bacteria like the common pathogen E. coli by severely damaging their
cell walls, according to a recent report from Yale researchers in the
American Chemical Society (ACS) journal Langmuir.

"We began the study out of concerns for the possible toxicity of
nanotubes in aquatic environments and their presence in the food
chain," said Menachem Elimelech, professor and chair of chemical and
environmental engineering at Yale and senior author on the paper.
"While nanotubes have great promise for medical and commercial
applications there is little understanding of how they interact with
humans and the environment."

Lisa Pfefferle Lisa Pfefferle

"The nanotubes are microscopic carbon cylinders, thousands of times
smaller than a human hair that can be easily taken up by human cells,"
said Elimelech. "We wanted to find out more about where and how they
are toxic."

This "nanoscience version of a David-and-Goliath story" was hailed in
an ACS preview of the work as the first direct evidence that "carbon
nanotubes have powerful antimicrobial activity, a discovery that could
help fight the growing problem of antibiotic resistant infections."

Using the simple E. coli as test cells, the researchers incubated
cultures of the bacteria in the presence of the nanotubes for up to an
hour. The microbes were killed outright - but only when there was
direct contact with aggregates of the SWCNTs that touched the bacteria.
Elimelech speculates that the long, thin nanotubes puncture the cells
and cause cellular damage.

E.coli incubated E.coli incubated E.coli incubated for one hour on
support matrix in the absence (1) or in the presence (2) of nanotubes.
(Elimelech/Yale)

The study ruled out metal toxicity as a source of the cell damage. To
avoid metal contaminants in commercial sources, the SWCNTs were
rigorously synthesized and purified in the laboratory of co-author
Professor Lisa Pfefferle.

"We're now studying the toxicity of multi-walled carbon nanotubes and
our preliminary results show that they are less toxic than SWCNTs,"
Elimelech said. "We are also looking at the effects of SWCNTs on a wide
range of bacterial strains to better understand the mechanism of
cellular damage."

Elimelech projects that SWCNTs could be used to create antimicrobial
materials and surface coatings to improve hygiene, while their toxicity
could be managed by embedding them to prevent their leaching into the
environment.

Other authors on the paper are Seoktae Kang and Mathieu Pinault. The
project was funded by a research grant from the National Science
Foundation.

Citation: Langmuir 23(17): 8670-8673 (August 28, 2007).

CONTACT: Janet Rettig Emanuel
Tel: +1 203 432 2157

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