Maverick Science mag 2013-14

B
reakthroughs in technology
are expanding the
limits of what’s possible
in biophysics research.
Samarendra Mohanty is
helping to push those
boundaries by developing
new tools to discover
safer, more efficient ways
to treat disease and study the human body.
Mohanty, a UT Arlington assistant professor of
physics, is using the principles of biophysics –
studying biological processes and materials by
means of the theories as well as the tools of physics
– to find new and innovative ways to alter biological
systems down to the molecular level. He and
his students are improving cutting-edge tools such
as optical tweezers, specialized optical microscopes
and optogenetics (the science of controlling brain
activity with light) to understand and influence
processes in cells and cellular networks.
“We have taken an integrated approach of cellular
manipulation, activation and control by optical
as well as hybrid approaches, combined with
a variety of imaging methods to visualize and
quantify responses in in-vitro and in-vivo models,”
Mohanty said. “In order to evaluate miniscule
changes to cell membranes during optical manipulation,
we developed a unique multimodal imaging
platform integrated with laser scissors,
tweezers, spanners, transporters and stimulators
here at UT Arlington.”
At the moment, Mohanty and the Biophysics
and Physiology Laboratory group he leads are
working on projects in five major research areas,
along with a number of smaller projects. He keeps
up a relentless pace in preparing and submitting
grant proposals which have brought millions of
dollars in research support from the National Institutes
of Health, National Science Foundation
and other sources. He authors and co-authors
manuscripts which are regularly published in top
journals.
“His projects are highly imaginative. He’s doing
an intriguing combination of physics, biology,
chemistry and biomechanics,” said Alex Weiss,
professor and chair of the Department of Physics.
“He’s doing very interesting research with nerve
cells and optical stimulation of the brain, among
other things. The work his group is doing has a lot
of potential to improve medical research and treatment
of disease down the road.”
A
s excited as he is by his
group’s current work,
Mohanty is even more
thrilled by the research
he envisions happening
in his lab in the years
ahead. He wants to shift
his main focus from different
aspects of neuronal
manipulation, imaging and control, to the
Brain Research through Advancing Innovative
Neurotechnologies (BRAIN) initiative, an effort
unveiled by President Barack Obama in April 2013
which is intended to revolutionize understanding
of the human brain through groundbreaking research.
This image shows a highly-controlled laser transfection of
ChR2-YFP gene into a targeted area of retina (green is
ChR2-YFP and blue is nuclei) by a near-infrared femtosecond
laser microbeam. Image courtesy of Samarendra Mohanty.
This illustration
demonstrates the
non-invasiveness of
two-photon optogenetic
stimulation. It
shows brain tissue
damage by an invasive
fiber delivering
one-photon stimulation
(shown in
blue) vs. non-invasive,
two-photon
stimulation (shown
in red). Illustration
courtesy of
Samarendra
Mohanty.
One of Mohanty’s current projects which could
be useful in the BRAIN initiative is the development
of a tiny tool which could help scientists map
and track interactions between neurons inside different
areas of the brain. The fiber-optic, two-photon,
optogenetic stimulator builds on a previous
Mohanty discovery that near-infrared (NIR) light
can be used to stimulate a light-sensitive protein
introduced into living cells and neurons in the
brain. This new method could show how different
parts of the brain react when a linked area is stimulated.
“Scientists have spent a lot of time looking at
the physical connections between different regions
of the brain. But that information is not sufficient
unless we examine how those connections function,”
Mohanty said. “That's where two-photon optogenetics
comes into play. This is a tool not only
to control the neuronal activity but to understand
how the brain works.”
The two-photon optogenetic stimulation involves
introducing the gene for ChR2, a protein
that responds to light, into a sample of excitable
tissue cells. A fiber-optic infrared beam of NIR
light can then be used to precisely excite the neurons
in a tissue circuit. In the brain, researchers
could then observe responses in the excited area
as well as other parts of the neural circuit. In living
subjects, scientists could also observe the behavioral
outcome, Mohanty said.
Optogenetic stimulation avoids damage to living
tissue by stimulating neurons with light instead
of electric pulses used in past research. Mohanty’s
method of using low-energy NIR
light also enables more precision and a
deeper focus than the blue or green light
beams often used in optogenetic stimulation.
Kamal Dhakal, a third-year doctoral
student in Mohanty’s lab, works in optogenetics
and optical manipulation of cells. He
says the multidisciplinary approach of Mohanty’s
research is preparing him well for
a career in optics and biophotonics. Dhakal
was lead author of a paper on the brain
mapping research that was published in
the June 1, 2013 edition of the journal Optics
Letters; Mohanty, doctoral student
Bryan Black and postdoctoral researcher
Ling Gu were co-authors.
“Dr. Mohanty is very good researcher
and has fancy ideas and visions,” Dhakal
said. “He is very frank, like a friend, and
helpful. Before joining his lab, I did not
have any technical knowledge such as
using computer software for data analysis,
interfacing instruments with computers,
imaging, programming, even how to make
a good graph. But today, I know all of them.
In addition, my projects require a wide variety
of knowledge, from genetics to optics,
mammalian cells to bacterial cells, electrophysiology
to digital holography. These
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