May 20, 2003 

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Gene Detectives (video)
March 06, 2003

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Interviewees: Stephen Turner, Nanofluidics, Inc. and Harold G. Craighead, Cornell Nanobiotechnology Center.

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Produced by Ann Marie Cunningham

Copyright © ScienCentral, Inc. with additional footage from NBC News, the National Cancer Institute and Cornell University.

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If anyone in your family has been diagnosed with cancer or another serious illness, chances are you wonder whether it could happen to you, too. Right now, finding out what’s in your genes is costly and time-consuming.

But as this ScienCentral News video reports, gene analysis could become much, much easier and considerably cheaper - because of a new technique that one scientist stumbled upon by accident.

Lucky Break

In 1999, Stephen Turner was a graduate student, working on his thesis at Cornell University’s Nanobiotechnology Center. One night, he was working late in his lab, bent over a microscope looking at strands of DNA moving through incredibly tiny sieves for separating molecules. He was looking for ways to separate DNA - a necessary step for gene mapping, or sequencing. Right now, only those at great risk of genetic disease have their genes mapped. But if the technique could be made faster and cheaper, Turner thought, more doctors and patients could take advantage of genetic information.

Suddenly, Turner realized that he had set up his experiment incorrectly. So he immediately pressed “Stop” on the keyboard of his computer, from which he was directing the movement of the DNA strands. Through his microscope, Turner then saw something unexpected - a sight that no scientist had ever seen before.

“I remember very clearly,” Turner recalls. “It was pretty exciting. I saw the DNA molecules separate from each other, the long strands from the short strands, in a matter of just a few seconds” - many times faster than he had ever expected. Turner made a videotape of the DNA strands separating at unprecedented speed. The next morning, he called his advisor, nanobiotechnologist Harold G. Craighead, down to the lab to view the tape.

Craighead recognized immediately that they were looking at “something people hadn’t seen before, a very dramatic effect that was unmistakable. I was just captivated.”

From Nano Lab to Nano Enterprise

Turner and Craighead set out to explain what had prompted DNA strands to separate so quickly. Turner had been using an electric force to push DNA molecules into the sieve, a very confined space, where they had to align in orderly ways. But DNA strands naturally prefer to be jumbled and disorderly. When Turner stopped the electronic force that was pushing the molecules into that tiny space, the molecules could recoil back into their usual disorder. Turner and Craighead call this behavior entropic recoil.

The new technique, Turner says, separates DNA strands quickly because “longer molecules take more time to enter the sieve than short molecules do. So if we cut the electric field, the longer molecules pull themselves out of the confining nanostructure, and the shorter molecules remain behind. In one step, we’re able to stretch out DNA molecules, and sort them according to length.”

Right now, Craighead says, DNA separation requires a great deal of material, laboratory space, and time. But he foresees that with the new technique, “what used to take days could take a few minutes. With a small amount of material and limited processing, you get answers much more rapidly.”

Part of Cornell’s role as a center of nanotechnology research is to encourage new business. Craighead and Turner have licensed the new DNA separation technique and other technologies.

They are cofounders of Nanofluidics, a company that plans to make genetic analysis easily and inexpensively available to doctors and patients. In your doctor’s office, Craighead says, you could find out “much more quickly whether you had a serious disease or a mild illness.”

This research is funded by the National Institutes of Health (NIH), and the National Science Foundation (NSF).

by Ann Marie Cunningham

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