February 7, 2008 / 8:38 PM / 10 years ago

New laser spectrometer provides instant analysis

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,” he said.

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,” he said.

Editing by Will Dunham and Eric Walsh

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