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Features for Senior Citizens
Scientists May Be on the Way to a Breathalyzer to
See if You have Cancer
Someday may allow doctors to screen people for
diseases simply by sampling their breath,
|
U.C. physics doctoral student Michael Thorpe
holds a detection chamber next to a novel laser apparatus at
JILA. Thorpe and JILA's Jun Ye led the study showing how
scientists can use laser light to detect faint breath molecules
that may be biomarkers for disease. |
Feb. 18, 2008 - Could there be a breathalyzer to find out if you
have a cancer in your body? By blasting a person's breath with laser
light, scientists from the National Institute of Standards and
Technology and the University of Colorado at Boulder have shown that
they can detect molecules that may be markers for diseases like asthma
or cancer.
While the new technique has yet to be tested in
clinical trials, it may someday allow doctors to screen people for
certain diseases simply by sampling their breath, according to the
research team from JILA, a joint institute of NIST and CU-Boulder.
"This technique can give a broad picture of many
different molecules in the breath all at once," said Jun Ye, a fellow of
JILA and NIST who led the research.
CU-Boulder graduate research assistant Michael
Thorpe, Ye, CU-Boulder doctoral student Matthew Kirchner and former CU
graduate student David Balslev-Clausen describe the research in a paper
that appeared in the Feb. 18 online edition of Optics Express, the free,
open-access journal published by the Optical Society of America.
Known as optical frequency comb spectroscopy, the
technique is powerful enough to sort through all the molecules in human
breath and sensitive enough to distinguish rare molecules that may be
biomarkers for specific diseases, said Ye.
When breathing, people inhale a complex mixture of
gases, including nitrogen, oxygen, carbon dioxide, water vapor and
traces of other gases like carbon monoxide, nitrous oxide and methane,
said Ye, an adjoint professor of physics at CU-Boulder. Exhaled breath
contains less oxygen, more carbon dioxide and a rich collection of more
than a thousand types of other molecules, most of which are present only
in trace amounts.
Just as bad breath can indicate dental problems,
excess methylamine may signal liver and kidney disease, ammonia may be a
sign of renal failure, elevated acetone levels can indicate diabetes and
nitric oxide levels can be used to diagnose asthma, Ye said.
When many breath molecules are detected
simultaneously, highly reliable, disease-specific information can be
collected, said Ye. Asthma, for example, can be detected much more
reliably when carbonyl sulfide, carbon monoxide and hydrogen peroxide
are all detected simultaneously with nitric oxide.
While current breath analysis using biomarkers is a
noninvasive and low-cost procedure, approaches are limited because the
equipment is either not selective enough to detect a diverse set of rare
biomarkers or not sensitive enough to detect particular trace amounts of
molecules exhaled in human breath, Ye said.
"The new technique has the potential to be
low-cost, rapid and reliable, and is sensitive enough to detect a much
wider array of biomarkers all at once for a diverse set of diseases," he
said.
The optical frequency comb is a very precise laser
for measuring different colors, or frequencies, of light, said Ye. Each
comb line, or "tooth," is tuned to a distinct frequency of a particular
molecule's vibration or rotation, and the entire comb covers a broad
spectral range -- much like a rainbow of colors -- that can identify
thousands of different molecules.
Laser light can detect and distinguish specific
molecules because different molecules vibrate and rotate at certain
distinct resonant frequencies that depend on their composition and
structure, he said. He likened the concept to different radio stations
broadcasting on separate radio frequencies.
The optical frequency comb was developed in the
1990s by Ye's JILA, NIST and CU-Boulder colleague John L. "Jan" Hall and
Theodor W. Hδnsch of Germany's Max-Planck Institute, who shared the 2005
Nobel Prize in physics with Roy J. Glauber for their work.
Ye's group has pioneered the application of
frequency combs to spectroscopy, or the analysis of light emitted or
absorbed by matter. The technique allows for many different gases to be
detected all at once with high sensitivity through their interaction
with light from such "combs," demonstrated by Thorpe, Ye and colleagues
in the journal Science, in 2006.
To test the technology, Ye's team had several
CU-Boulder volunteer students breathe into an optical cavity -- a space
between two curved mirrors -- and then directed sets of ultrafast laser
pulses into the cavity. As the light pulses ricocheted around the cavity
tens of thousands of times, the researchers determined which frequencies
of light were absorbed, indicating which molecules -- and their
quantities -- were present by the amount of light they absorbed.
Ye and his colleagues detected trace signatures of
gases like ammonia, carbon monoxide and methane from the samples of
volunteers. In one measurement, they detected carbon monoxide in a
student smoker that was five times higher compared to a nonsmoking
student, Ye said.
Funding was provided by the Air Force Office of
Scientific Research, Agilent Technologies Foundation, the Defense
Advanced Research Projects Agency, NIST, the National Science Foundation
and a CU-Boulder proof of concept grant.
A podcast with Ye and Thorpe is posted on the Web
Click Here
Link also available on this page -
http://www.colorado.edu/news/podcasts/.
About OSA
Uniting more than 70,000 professionals from 134
countries, the Optical Society of America (OSA) brings together the
global optics community through its programs and initiatives. Since 1916
OSA has worked to advance the common interests of the field, providing
educational resources to the scientists, engineers and business leaders
who work in the field by promoting the science of light and the advanced
technologies made possible by optics and photonics. OSA publications,
events, technical groups and programs foster optics knowledge and
scientific collaboration among all those with an interest in optics and
photonics. For more information, visit
www.osa.org.
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