COLUMBUS , Ohio – Ohio State University
researchers have invented a process for uncoiling
long strands of DNA and forming them into precise
patterns.
Ultimately, these DNA strands could
act as wires in biologically based electronics and
medical devices, said L.
James Lee , professor of chemical
and biomolecular engineering at Ohio State University .
In the early online edition of the Proceedings
of the National Academy of Sciences , Lee and
postdoctoral researcher Jingjiao
Guan describe how they used a tiny rubber
comb to pull DNA strands from drops of water and
stamp them onto glass chips.
Other labs have formed very simple
structures with DNA, and those are now used in devices
for gene testing and medical diagnostics. But Lee
and Guan are the first to coax strands of DNA into
structures that are at once so orderly and so complex
that they resemble stitches on a quilt.
“These are very narrow, very long wires
that can be designed into patterns for molecular
electronics or biosensors,” Lee said. “And in our
case, we want to try to build tools for gene delivery,
DNA recombination, and maybe even gene repair, down
the road.”
The longest strands are one millimeter
(thousandths of a meter) long, and only one nanometer
(billionths of a meter) thick. On a larger scale,
positioning such a long, skinny tendril of DNA is
like wielding a human hair that is ten meters (30
feet) long. Yet Lee and Guan are able to arrange
their DNA strands with nanometer precision, using
relatively simple equipment.
“Basically,
we're doing nanotechnology using only a piece
of rubber and a tiny droplet of DNA solution.” |
In this patent-pending technology,
the researchers press the comb into a drop of water
containing coils of DNA molecules. Some of the DNA
strands fall between the comb's teeth, so that the
strands uncoil and stretch out along the surface
of the comb as it is pulled from the water.
They then place the comb on a glass
chip surface. Depending on how they place the comb,
they leave behind strands of different lengths and
shapes.
“Basically, we're doing nanotechnology
using only a piece of rubber and a tiny droplet of
DNA solution,” Guan said.
Computer chips that bridge the gap
between the electronic and the biological could make
detection of certain chemicals easier, and speed
disease diagnosis. But first, researchers must develop
technologies to mass produce DNA circuits as they
produce chip circuits today.
The technique that Lee and Guan used
is similar to a relatively inexpensive chip-making
technology called soft lithography, where rubber
molds press materials into shape.
In this study, they arranged the DNA
into rows of “stitches,” pinstripes and criss-cross
shapes.
The pinstripes presented the researchers
with a mystery: for some reason, thorn-like structures
emerged along the strands at regular intervals.
“We think the ‘thorns' may be used
as interconnects between nanowires, or they could
connect the nanowires with other electronic components,” Guan
said. “We are not trying to eliminate them, because
we do not think they are defects. We also believe
their formation is controllable, because they are
almost completely absent in some experiments but
abundant in others. Although we currently do not
know exactly how the thorns form, maybe new and useful
nanostructures may be created if we can better understand
and control this process.”
The university will license the technology
for further development. Lee and Guan are working
on their first application – building the wires into
sensors for detecting disease biomarkers. In the
meantime, they are collaborating with researchers
in the Department
of Electrical and Computer Engineering at Ohio State to
measure the electrical properties of the DNA wires.
They are also using this technique to produce DNA-based
nanoparticles for gene delivery.
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Contact: L. James Lee, (614) 292-2408; Lee.31@osu.edu
Jingjiao Guan, (614) 688-4400; Guan.13@osu.edu
Written by Pam Frost Gorder, (614)
292-9475; Gorder.1@osu.edu
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