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Deborah Kelly, an assistant professor in the Virginia Tech Carilion Research Institute, has now developed a novel technology platform to peer closely into the world of cells and molecules within a native, liquid environment.
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A
photograph of a polar bear in captivity, no matter how sharp the
resolution, can never reveal as much about behavior as footage of that
polar bear in its natural habitat. The behavior of cells and molecules
can prove even more elusive. Limitations in biomedical imaging
technologies have hampered attempts to understand cellular and molecular
behavior, with biologists trying to envision dynamic processes through
static snapshots.
Deborah
Kelly, an assistant professor in the Virginia Tech Carilion Research
Institute, has now developed a novel technology platform to peer closely
into the world of cells and molecules within a native, liquid
environment.
Kelly
and colleagues have developed a way to isolate biological specimens in a
flowing, liquid environment while enclosing those specimens in the
high-vacuum system of a transmission electron microscope (TEM). The TEM
liquid-flow holder, developed by Protochips Inc. of Raleigh, N.C.,
accommodates biological samples between two semiconductor microchips
that are tightly sealed together. These chips form a microfluidic device
smaller than a Tic Tac. This device, positioned at the tip of an EM
specimen holder, permits liquid flow in and out of the holder. When
these chips are coated with a special affinity biofilm that Kelly
developed, they have the ability to capture cells and molecules rapidly
and with high specificity. This system allows researchers to watch—at
unprecedented resolution—biological processes as they occur, such as the
interaction of a molecule with a receptor on a cell that triggers
normal development or cancer.
"With
this new technology, we can capture and view the native architecture of
cells and their surface protein receptors while learning about their
dynamic interactions, such as what happens when cells interact with
pathogens or drugs," said Kelly. "We can now isolate cancer cells, for
example, and view the early events of chemotherapy in action."
click to enlarge
Affinity capture devices produced on commercial silicon nitride microchips (a) contain viewing windows (b) that allow an electron microscope beam to penetrate to the specimen level. Devices can be functionalized with lipid monolayers (c) containing Ni-NTA heads groups (red circles) that bind to His-tagged protein targets (red complexes) (d). |
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Kelly
had previously worked with colleagues at Harvard Medical School to
develop a way to capture protein machinery in a frozen environment. "But
life moves," said Kelly. "It’s better if biological processes don’t
have to be paused or frozen in order to be studied, but can be viewed in
dynamic and life-sustaining liquid environments."
Kelly’s affinity capture device,
in combination with high-resolution TEM, helps bridge the gap between
cellular and molecular imaging, allowing researchers to achieve spatial
resolution as high as two nanometers. "This device allows us to see new
features on the surface of live cancer cells, providing new targets for
drug therapy," Kelly said. "With this resolution, scientists may even be
able to visualize disease processes as they unfold."
The
research appears in the February issue of RSC Advances, an
international journal of the Royal Society of Chemistry of London, in
the article "The development of affinity capture devices -- a nanoscale
purification platform for biological in situ transmission electron
microscopy," by Katherine Degen, a biomedical engineering student at the
University of Virginia; Madeline Dukes, an applications scientist at
Protochips; Justin Tanner, a postdoctoral associate at the Virginia Tech
Carilion Research Institute; and Kelly, the corresponding author.
The development of affinity capture devices -- a nanoscale purification platform for biological in situ transmission electron microscopy
SOURCE
