Nanosensors For Astronauts: Tiny Devices Will Fit Inside Cells; Monitor Signs Of Radiation Damage 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 pinhead.

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.