A scientist
holds blood samples in a laboratory (AFP/File, Luis Robayo)
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PARIS —
Scientists in Britain say they have developed a super-sensitive test using
nano-particles to spot markers for cancer or the AIDS virus in human blood
serum using the naked eye.
As it does
not need sophisticated equipment, the test-tube technique should be cheap and
simple, making it a a boon for disease detection in poor countries, the team
wrote in Nature Nanotechnology on Sunday.
Researchers
from Imperial College London used the technology to scan for molecules of p24,
a marker for HIV infection, and Prostate Specific Antigen or PSA, an early
indicator of prostate cancer.
Their
method is used to analyse serum, a light-yellow fluid that is extracted from
blood by a centifuge and is commonly used in health tests.
"If
the result is positive for p24 or PSA, there is a reaction that generates
irregular clumps of nanoparticles, which give off a distinctive blue hue in a
solution inside the container," said a statement.
The
reaction, in response to the presence of antibodies, occurred even at ultra-low
concentrations of p24 or PSA.
"If
the results are negative, the nanoparticles separate into ball-like shapes,
creating a reddish hue. Both reactions can be easily seen by the naked
eye."
Nanoparticles
are microscopic clusters of atoms sized between one and 100 nanometres (a
billionth of a metre), that are seen as a promising field of research for their
potential in delivering medicines, for example.
The team
said their visual sensor technology was 10 times more sensitive than existing
standard methods for measuring p24 and PSA biomarkers -- molecules that can
indicate the presence of disease.
It was able
to detect minute levels of p24 in patients with low viral loads that went
undetected using some existing tests.
The new
method was also 10 times cheaper.
Study
co-author Roberto de la Rica said the test would allow people to be diagnosed
at an earlier state of disease, and thus treated sooner.
"We
also believe that this test could be significantly cheaper to administer, which
could pave the way for more widespread use of HIV testing in poorer parts of
the world."
But study
co-author Molly Stevens told AFP the method had yet to be tested in a large
patient trial to confirm its usefulness.
As yet, the
technique cannot pinpoint how big the concentration of HIV or cancer markers
is.
"It is
an 'on-off' test," Stevens cautioned. "It does not say specifically
how many biomarkers are in blood, but only if they are present."
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