Scientists creating sensors that can fit inside blood cells

Sunday, August 18, 2002

DETROIT -- Researchers are creating "Star Trek"-like radiation sensors that are so small, they could be absorbed into the white blood cells of astronauts and could someday be used to treat and diagnose illnesses.

Astronauts constantly are exposed to radiation, and radiation-induced illness is a serious concern in space travel.

The sensors would continuously monitor for early signs of damage, said Dr. James Baker Jr., a University of Michigan scientist who is directing the project.

With the nanomolecular devices in their white blood cells, astronauts would feel no more intrusion than when they fly with regular staples, such as freeze-dried food.

One million nanometers are about the diameter of a pinhead. The sensors, in theory similar to the Borg nanoprobes implanted in "Star Trek: Voyager" character Seven of Nine, resemble spheres with a diameter of less than five nanometers.

University researchers say the devices could revolutionize the practice of medicine on earth and in space, a contention supported by the non-profit National Space Biomedical Research Institute in Houston.

"In principle, this could be possible. It's very exciting. It's an emerging technology that is really revolutionary," said Dr. Jeffrey Sutton, director of the institute, which is not associated with the research.

Made layer by layer

For the sensor, the scientists are creating synthetic polymers called dendrimers, layer by layer. Added to it is a substance such as a vitamin that white blood cells called lymphocytes would want to draw inside themselves. Also added is a fluorescent molecule -- two dyes hooked together by a small protein.

If radiation is present in a cell, the protein hook breaks, the dyes become unhooked and then the cell glows, Baker said.

The glow is measured by a retinal-scanning device using a "laser capable of detecting fluorescence from lymphocytes as they pass one-by-one through narrow capillaries in the back of the eye," he said.

The retinal scans are similar to ones used in the Tom Cruise science fiction film "Minority Report." In the movie, eye scans are used to determine someone's identity.

The sensor could be injected or perhaps administered transdermally or through the skin.

Hopes to test on mice

"We've actually made the device and put it into tissue culture cells and showed that it worked," Baker said. "We hope to have data from animals within three years."

He hopes to test the sensors in mice in space within six years. Human trials would come later.

The research is part of a $2 million, three-year grant from NASA and the National Cancer Institute to develop biomolecular sensors.

Nanosensors would avoid the problems associated with implantable sensors, which can cause inflammation, and eliminate the need to draw and test blood samples.

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