Cornell’s E. Coli “Pregnancy Test”
—Pathogen detection in minutes!

It seems that every week a new, better, faster model for pathogen detection is brought to market. This week is no different. The latest development comes from Cornell University’s Department of Food Science and Technology, and it functions, according to its developers, like a home pregnancy test.

The newly developed sensor, the work of a research team headed by Richard A. Durst, professor of chemistry at Cornell’s Agricultural Experiment Station in Geneva, New York, has reportedly been able to detect the presence of the pathogens E. coli , Cryptosporidium and Listeria in just eight minutes. It works through the use of liposomes, microscopic, cell-like structures produced in the lab by adding an aqueous, marker-containing solution (such as a dye) to a phospholipid mixture. On the outside of these structures’ membranes, the Cornell researchers have affixed antibodies. When a pathogen, such as E.coli, is detected, it binds to the antibodies and the liposome membrane is ruptured, releasing the dye or other marker.

In one format, paperlike test strips impregnated with liposomes were placed in a solution containing E. coli. As the liquid was drawn up the strip, it crossed the liposome-coated area. The pathogens were drawn to the antibodies on the liposome membrane, causing the membrane to react and rupture, releasing marker dye molecules. The change in color of the test strip indicated the presence of E. coli.

“Because each liposome contains hundreds of thousands to perhaps millions of marker molecules, there is a large amplification effect when the liposome is ruptured and the markers are released,” says Durst. “Since detection and signal amplification using liposome labels are not dependent on a secondary reaction—such as what is required for conventional enzyme-based tests—the use of liposomes has the advantage of providing immediate warning of the presence of the pathogen.”

Cornell has licensed the technology to Innovative Biotechnologies International, Inc. (www.ibi.cc/), which has transferred the technology into field tests for Cryptosporidium parvum , an intestinal parasite, sometimes found in natural and municipal waters that causes diarrhea. “The beauty of the Durst technologies,” explains Richard Montagna, president of Innovative Biotechnologies, “is that they are exquisitely sensitive, and can be used alone or in a broad array of biosensors.”

Innovative Biotechnologies International hopes to have a product ready for the food industry by 2003.

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