Akos
Vertes (L), professor of chemistry, biochemistry, and molecular
biology, and graduate student Peter Nemes show their detector, which
combines a laser with a mass spectrometer to provide on-the-spot
analysis that researchers hope will have applications ranging from
evaluating a tumour as it is removed to quickly detecting explosives in
luggage
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 tumour as it is removed, to quickly detecting
explosives in luggage.
The laser vapourises tiny samples that
can be instantly analysed by the spectrometer, and can be used even on
living organisms, the US team said on Thursday.
“We are talking
about less than a second for an analysis,” said Akos Vertes, a
professor of biochemistry and molecular biology at George Washington
University.
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 colour changes in a living plant leaf
and to find explosives residue on a currency note.
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 ionisation, or LAESI, it requires a
desk-sized space in a laboratory. But smaller spectrometers and lasers
could make it portable, Vertes said.
The laser burns the living
tissue, vapourising some of it and sending particles up into the air in
a puff. In a process called electrospray ionisation, 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 mass spectrometer then measures the charged particle, called an ion.
Vertes
and Nemes say the ionising drops can be shot from a tiny nozzle that
can be bundled with a fibre-optical cable carrying the laser beam, and
a small tube to carry the sample into the spectrometer to be analysed.
“You can just go into the field and put your laser on the surface you want to
analyse,” Vertes said.
By taking a series of samples, the detector can analyse cell-by-cell changes.
This
could help biologists understand a living system, and could help
surgeons as well - for example, by analysing tumours 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.
Vertes
is also 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.
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