MINNEAPOLIS
/ ST. PAUL--The DNA molecule--nature's premier data
storage material--may hold the key for the information
technology industry as it faces demands for more
compact data processing and storage circuitry. A
team led by Richard Kiehl, a professor of electrical
engineering at the University of Minnesota, has
used DNA's ability to assemble itself into predetermined
patterns to construct a synthetic DNA scaffolding
with regular, closely spaced docking sites that
can direct the assembly of circuits for processing
or storing data. The scaffolding has the potential
to self-assemble components 1,000 times as densely
as the best information processing circuitry and
100 times the best data storage circuitry now in
the pipeline.
Members of the team first published their innovation
in 2003, and they have now refined the technique
to allow more efficient and more versatile assembly
of components. The new work, which was a collaborative
effort with chemistry professors Karin Musier-Forsyth
and T. Andrew Taton at Minnesota and Nadrian C.
Seeman at New York University, is reported in the
December issue of Nano Letters, a publication of
the American Chemical Society.
"There's a need for programmability and precision
on the scale of a nanometer--a billionth of a meter--in
the manufacture of high-density nanoelectronic circuitry,"
said Kiehl. "With DNA scaffolding, we have
the potential for arranging components with a precision
of one-third of a nanometer.
"In
a standard silicon-based chip, information processing
is limited by the distance between units that process
and store information. With DNA scaffolding, we
can lay out devices closely, so the interconnects
are very short and the performance very high."
The
DNA scaffolding is made from synthetic DNA "tiles"
that spontaneously assemble in a predetermined pattern
to form a sheet of molecular fabric, much like corduroy.
The ripples in the fabric are formed by rows of
sticky DNA strands that occur at regular intervals
in the scaffolding and function as a strip of Velcro®
hooks that fasten to nanocomponents coated with
matching DNA strands. The nanocomponents could be
metallic particles designed to process or store
data in the form of an electrical or magnetic state,
or they could be organic molecules--whatever would
best process or store the information desired.
In
the earlier work, members of the Kiehl team made
DNA scaffolding with regularly spaced gold nanocomponents
pre-woven into the fabric, completing the synthesis
all in one operation. Now, the team first makes
DNA scaffolding with regularly spaced sticky DNA
strips and then adds the nanocomponents, which stick
to the DNA strips in rows. This allows them to use
optimal synthetic methods for both steps. It's analogous
to using strips of Velcro® in cloth: It's much
easier to get a useful pattern by first weaving
cloth and Velcro® strips together, and then
attaching beads or other objects to the strips later,
than it is by adding the objects during the weaving
process.
The
new procedure also lets the team add any one of
various nanocomponents--such as other metals, organic
molecules or tiny electronic devices--at a later
time, depending on what is needed for the application.
The result is a more perfect scaffolding, better
and more regular attachment of electronic units,
and more diversity in the types of units and the
types of circuitry that can be made.
"We
can now assemble a DNA scaffolding on a preexisting
template, such as a computer chip, and then--on
the spot--assemble nanocomponents on top of the
DNA," said Kiehl. The nanocomponents can hold
electrical charge or a magnetic field, either of
which would represent a bit of data, and interactions
between components can act to process information.
Circuitry based on regular arrays of closely spaced
components could be used for quickly recognizing
objects in a video image and detecting motion in
a scene -- slow and difficult tasks for conventional
computer chips. The technology could help computers
identify objects in images with something approaching
the speed of the human eye and brain, Kiehl said.
The technology could also be used for various other
applications, including chemical and biological
sensing, in which case the strips would be designed
to stick to the tiny objects or molecules to be
detected.
The work was supported by the National Science Foundation.
Contacts:
Richard Kiehl, electrical engineering professor,
(612) 625-8073
Deane Morrison, University News Service, (612) 624-2346
