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TECHNOLOGY REVIEW /
FROM THE LABS 93
WAKE FOREST UNIVERSITY SCHOOL OF MEDICINE
hard structures within the polyure-
thane, so those are what they preferen-
tially aggregate with, rather than with
the soft, amorphous regions.
NEXT STEPS: Reducing the amount
of solvent used could make the manu-
facturing process cleaner and easier.
Making actual products from the
material may require adjusting manu-
facturing techniques: too much heat
during processing may reduce the
material s sti ness.
An easier way to make nanowire
sensors and integrate them into
electronics could lead to handheld
detectors of pathogens, cancer
S OU RCE: "Label-Free Immunodetection
with CMOS-Compatible Semiconducting
Eric Stern et al.
Nature 445: 519--522
RESULTS: Researchers at Yale Univer-
sity have found an easier way to manu-
facture nanowire sensors, and their
process is compatible with those used
to make computer chips. The sen-
sors can detect small concentrations
of proteins about as reliably as previ-
ous nanowire sensors could.
WHY IT MATTERS: Today, detect-
ing biological molecules in ultrasmall
concentrations requires tagging them
with fluorescent dyes and viewing
them through bulky optical readers.
Nanowire sensors generate electronic
signals rather than optical ones, and
they do not require tagging, so they
can be much smaller and easier to use.
As a result, they could lead to hand-
held sensors that can screen for faint
traces of hundreds of pathogens or for
early signs of cancer. The new tech-
nique could also make it much easier
to integrate nanosensors and the elec-
tronics that process their signals on
individual chips. Such sensors would
be more practical to mass-produce.
METHODS: The researchers first
created patterns on silicon using con-
ventional lithography; chemical etch-
ing then removed the nonpatterned
silicon, leaving behind silicon wires.
But because the wires were still too
thick, the researchers let the etching
agent continue to eat away at the mate-
rial under the edges of the patter n.
NEXT STEPS: The researchers are
demonstrating the sensors ability to
detect different molecules, such as
virus particles, DNA, and a wider
range of proteins.
Stem Cells from
Cells collected during pregnancy
could aid research and therapy
SOU RCE: "Isolation of Amniotic Stem
Cell Lines with Potential for Therapy"
Paolo De Coppi et al.
Nature Biotechnology 25(1): 100--106
RESULTS: Scientists have isolated
stem cells from amniotic fluid and
found that they appear to have prop-
erties similar to those of embryonic
stem cells. The cells grew e ciently in
the lab, doubling in number every 36
hours, and were able to develop into
precursors of multiple tissue types,
including brain tissue.
WHY IT MATTERS: Unlike embryonic
stem cells, cells routinely discarded dur-
ing amniocentesis could be har vested
without destroying human embryos,
avoiding the ethical concerns that have
slowed stem cell research. And unlike
most adult stem cells, those derived
from amniotic uid appear to grow e -
ciently and can di erentiate into mul-
tiple cell types, making them suitable
for therapeutic and research uses.
METHODS: The researchers, led by
Anthony Atala at Wake Forest, col-
lected samples of amniotic uid and
isolated cells that expressed a mole-
cule unique to stem cells. They then
grew the cells under di erent envi-
ronmental and chemical conditions to
trigger their di erentiation into di er-
ent cell types.
NEXT STEPS: The researchers plan
to try to develop the cells for use in
treating diseases. They ll try to make
ner ves for Parkinson s patients, for
instance, or insulin-secreting cells for
people with diabetes.
Keeps Brain Agile
People with a cholesterol-gene variant
are more likely to live longer, with
better brain function
SOURCE: "A Genotype of Exceptional
Longevity Is Associated with Preservation
of Cognitive Function"
Nir Barzilai et al.
Neurology 67(12): 2170--2175
RESULTS: A speci c version of a gene
involved in cholesterol transport may
also help keep the mind sharp in old
age. In a group of 158 Ashkenazi Jews
aged 95 and older, those with the
gene variant, which has previously
been linked to longevity, were twice
as likely to pass tests of mental agility
as those with a di erent version of the
gene. Among 124 people, aged 75 to
85, from an unrelated Ashkenazi popu-
lation, those individuals with the gene
variant were ve times as likely to be
free of dementia and perform well in
Researchers at Wake Forest have isolated
cells from amniotic fluid and, after multi-
plying the cells in the lab, are able to coax
them into becoming a particular cell type.
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