Researchers at the University of California at Los Angeles, together with scientists at NASA's Johnson Space Center in Houston, created a very porous matrix of silicon dioxide to encapsulate antibodies that bind to cortisol, a human hormone associated with stress response, said Esther Lan, a senior research associate at UCLA.
"The pores allow the (cortisol) to travel in and out, but the antibodies stay trapped," Lan told a session at the NanoSpace 2002 conference. "You don't need to chemically modify the antibody (to hold it in place)."
The gel is prepared with a set amount of fluorescent-tagged cortisol, which emits a specific light signal. Elevated levels of the hormone in an astronaut's sample displaces the tagged molecules, decreasing the signal from the gel.
"Research data indicated much better discrimination between cortisol concentrations with the technique as compared with the traditional (tests)," said Bruce Dunn, a materials science professor at UCLA, in a statement.
If an extremely thin film of the gel is deposited on a fiber-optic probe, changes in the light signal can be noted within seconds, Lan told the conference. The team is working to develop this method into a portable unit in a year or so, she said.
Such a device, expected to weigh about five pounds, could provide real-time data on astronaut stress during a mission, Lan said. Existing tests must wait until the mission is completed, she said.
The gel also provides a longer shelf life for detection agents, Lan said. The gel seems to confine the proteins and other molecules tightly enough to delay or prevent their decomposition, even under high temperatures, she said.
The team wants to expand the gel technique to a wider array of proteins, but needs to fine-tune its porosity, Lan said. Creating larger pores would mean more substances could reach the trapped antibodies, but that might also allow the antibodies to leak out. Further research will focus on ordering the pores to achieve the best balance between those actions, she said.
The conference, sponsored by the Institute for Advanced Multidisciplinary Research, NASA and several universities, was set up to help NASA and the research community work out joint goals for nanotechnology.
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