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Nanobiotechnology at Cornell News Service
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 whatâ€™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.
In 1999, Stephen
Turner was a graduate student, working on his thesis at Cornell
Universityâ€™s Nanobiotechnology Center. One night, he was working late
in his lab, bent over a microscope looking at strands of DNA moving through
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
“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,
G. Craighead, down to the lab to view the tape.
Craighead recognized immediately that they were looking at “something
people hadnâ€™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
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, weâ€™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 Cornellâ€™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 doctorâ€™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).