Along with space suits, freeze-dried food and
barf bags, tomorrow’s astronauts may travel with nanomolecular
devices inside their white blood cells to detect early signs of
damage from dangerous radiation or infection.

The National Aeronautics and Space Administration (NASA) is
investing $2 million to develop this "Star Trek" technology at
the University of Michigan Medical School’s Center for Biologic
Nanotechnology. The three-year research grant is the largest the
Medical School has ever received from NASA, according to James R.
Baker, Jr., M.D., who will direct the project.

"Our goal is to develop a non-invasive system that, when placed
inside the blood cells of astronauts, will monitor continuously
for radiation exposure or infectious agents," says Baker, the
Ruth Dow Doan Professor of Nanotechnology, a U-M professor of
internal medicine and the center’s director.

"Radiation-induced illness is a serious concern in space travel,"
says Baker. "Radiation changes the flow of calcium ions within
white blood cells and eventually triggers irreversible cell
death. Even if individual incidences of exposure are within
acceptable limits, the cumulative effect of radiation can be
toxic to cells. So, it’s important to monitor continuously for
early signs of damage."

U-M scientists will use expertise and technology acquired during
an ongoing nanotechnology research study funded by the National
Cancer Institute. In this project, U-M researchers are developing
intra-cellular devices to sense pre-malignant and cancerous
changes inside living cells.

Created from synthetic polymers called dendrimers, the devices
are fabricated layer-by-layer into spheres with a diameter of
less than five nanometers. A nanometer is one-billionth of a
meter. One million nanometers are equal to the diameter of a

Because the nanosensors are so small, Baker says they pass easily
through membranes into white blood cells called lymphocytes,
where they are in a perfect position to detect the first signs
of biochemical changes from radiation.

Nanosensors will avoid problems associated with current much-larger
implantable sensors, which can cause inflammation; and eliminate
the need to draw and test blood samples. U-M scientists hope the
devices can be administered transdermally — or through the
skin — every few weeks, avoiding the need for injections or IVs
during space missions.

"We can attach fluorescent tags to dendrimers, which glow in the
presence of proteins associated with cell death," Baker explains.
"Our plan is to develop a retinal-scanning device with a laser
capable of detecting fluorescence from lymphocytes as they pass
one-by-one through narrow capillaries in the back of the eye. If
we can incorporate the tagged sensors into enough lymphocytes, a
15-second scan should be sufficient to detect radiation-induced
cell damage."

If the first phase of research with lymphocytes is successful,
Baker plans to develop nanosensors targeted at other immune system
cells to monitor protein markers of infection. U-M scientists will
work initially with cell cultures, but plan later testing of the
nanosensor technology in research animals.

The NASA-funded research project will require the combined efforts
of U-M scientists from many different disciplines and academic
units within the university. In addition to Baker, senior members
of the research team are Theodore B. Norris, Ph.D., professor of
electrical engineering and computer science in the U-M College
of Engineering; Bradford G. Orr, Ph.D., professor of physics in
the College of Literature, Science, and the Arts; and Felix de
la Iglesia, M.D., adjunct professor of pathology in the Medical
School and an adjunct professor of environmental health sciences
in the School of Public Health.

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Glowing colors like these from chemical tags indicate various
stages of cell death. Photo credit: Felix de la Iglesia, M.D.,
University of Michigan