New laser spectrometer provides instant analysis
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By Maggie Fox, Health and Science Editor
Reuters
Thursday, February 7, 2008; 3:38 PM
WASHINGTON (Reuters) - A new detector combines a laser with a mass
spectrometer to provide on-the-spot analysis that researchers hope
will have applications ranging from evaluating a tumor as it is
removed to quickly detecting explosives in luggage.
The laser vaporizes tiny samples that can be instantly sampled and
analyzed by the spectrometer, and can be used even on living
organisms, the team at George Washington University said on Thursday.
"We are talking about less than a second for an analysis," Akos
Vertes, a professor of biochemistry and molecular biology at George
Washington University, said in an interview.
Vertes and graduate student Peter Nemes say they have used their
system to find a drug sample in urine, to detect the chemical changes
that accompany color changes in a living plant leaf and to find
explosives residue on a dollar bill.
The university has filed for a patent on the system, which Vertes
said is the first to use a laser for such instant analysis of living
tissue.
Called laser ablation electrospray ionization or LAESI, the system
requires a desk-sized space in a laboratory. But smaller
spectrometers and lasers could make it portable, Vertes said.
"It is still not pocket-sized,
The laser burns the living tissue, vaporizing some of it and sending
particles up into the air in a puff. In a process called electrospray
ionization, a stream of electrically charged droplets is shot at the
spot, intercepting the particles and merging with some of them to
make charged droplets.
The 2002 Nobel Prize in Chemistry was awarded to John Fenn for the
discovery of electrospray ionization.
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A mass spectrometer can measure any charged particle, called an ion.
Vertes and Nemes say the ionizing drops can be shot from a tiny
nozzle that can be bundled with a fiber-optical cable carrying the
laser beam, and a small tube to carry the sample into the
spectrometer to be analyzed.
"You can just go into the field and put your laser on the surface you
want to analyze," Vertes said.
By taking a series of samples, the detector can analyze cell-by-cell
changes.
"We hope it takes us to the biomedical field," Vertes said. "We want
to go in and pop one cell open, analyze the content and go on to the
next cell."
This could help biologists understand a living system, and could help
surgeons as well -- for example, by analyzing tumors as they are
removed. "You are already cutting the patient, so a little bit of a
prick with a laser is not much more," Vertes said.
"It is very important to know when the cancerous tissue ends and the
healthy tissue begins." Currently surgeons send samples to a
pathology lab but this system could save precious minutes, he said.
He is trying to use it to see stem cells in the process of
differentiating, or changing, into the various cell types that they
can give rise to.
Current methods require scientists to look for one change at a time
in each cell sample -- destroying the living cells in the
process. "The power of this method is with a single shot we can look
at 50 different metabolites,
(Editing by Will Dunham and Eric Walsh)
http://www.washingt
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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