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Standing: Oleg Gang (left) and Daniel van der Lelie.
Sitting: Mathew Maye (left) and Dmytro Nykypanchuk
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“Understanding how to self-assemble these
types of nanomaterials has applications in all areas of nanotechnology,
from optics to electronics to magnetic materials,” said the study’s
lead author Mathew Maye, a Brookhaven chemist. Maye is part of a team
of interdisciplinary scientists from Brookhaven’s new Center for
Functional Nanomaterials (CFN) and the biology department. The
researchers found a way to control the assembly of gold nanoparticles
using rigid, double-stranded DNA. Their technique takes advantage of
this molecule’s natural tendency to pair up components called bases,
known by the code letters A, T, G and C.
“In biology, DNA is mainly an informational
material, while in nanoscience, DNA is an excellent structural
material due to its natural ability to self-assemble according to
well-specified programmable rules,” said Oleg Gang, the Brookhaven
physicist who leads the research team. “Using biological materials
such as DNA, we are developing approaches to control the assembly of
inorganic nano-objects. However, in order to really turn this
attractive approach into nanotechnology, we have to understand the
complexity of interaction in such hybrid systems.”
The synthetic DNA used in the laboratory is capped
onto individual gold nanoparticles and customized to recognize and
bind to complementary DNA located on other particles. This process
forms clusters, or aggregates, of gold particles.
“It’s really by design,” Maye said. “We can sit
down with a piece of paper, write out a DNA sequence, and control how
these nanoparticles will assemble.”
One limitation to the assembly process is the use
of single-stranded DNA, which can bend backward and attach to the
particle’s gold surface instead of binding with surrounding
nanoparticles. This flexibility, along with the existence of multiple
forms of single-stranded DNA, can greatly slow the assembly process.
In the Brookhaven study, researchers introduced partially rigid,
double-stranded DNA, which forces interacting linker segments of DNA
to extend away from the gold surface, allowing for more efficient
assembly.
“By using properties of DNA, we can increase
assembly kinetics, or speed, by relatively simple means without a lot
of synthetic steps,” Maye said.
The research team probed the synthesized and
assembled nanosystems with multiple imaging techniques, using beams of
light and electrons as well as high-intensity x-rays at Brookhaven’s
National Synchrotron Light Source. The scientists look to further
improve the controllability of the system, focusing next on the size
of the nanoparticle clusters.
This research was funded by the Office of Basic
Energy Sciences within the U.S. Department of Energy’s Office of
Science. The CFN at Brookhaven Lab is one of five Nanoscale Science
Research Centers being constructed at national laboratories by the
DOE’s Office of Science to provide the nation with resources unmatched
anywhere else in the world for synthesis, processing, fabrication, and
analysis at the nanoscale. |
