Schematic
illustration of the experimental strategy: Double stranded DNA bundles (gray)
form
tetrahedral cages.
Single stranded DNA strands on the edges (green) and vertices (red) match up
with
complementary
strands on gold nanoparticles. This results in a single gold particle being
trapped
inside each
tetrahedral cage, and the cages binding together by tethered gold nanoparticles
at each
vertex. The result
is a crystalline nanoparticle lattice that mimics the long-range order of
crystalline
diamond. The
images below the schematic are (left to right): a reconstructed cryo-EM density
map of
the tetrahedron, a
caged particle shown in a negative-staining TEM image, and a diamond superlattice
shown at high
magnification with cryo-STEM.
(February 5, 2016) DNA
scaffolds cage and coax nanoparticles into position to form crystalline
arrangements that mimic the atomic structure of diamond
Using bundled strands of DNA to build Tinkertoy-like
tetrahedral cages, scientists at the U.S. Department of Energy's Brookhaven
National Laboratory have devised a way to trap and arrange nanoparticles in a
way that mimics the crystalline structure of diamond. The achievement of this
complex yet elegant arrangement, as described in a paper published February 5,
2016, in Science, may open a path to new materials that take advantage of the
optical and mechanical properties of this crystalline structure for
applications such as optical transistors, color-changing materials, and
lightweight yet tough materials.
"We solved a 25-year challenge in building diamond
lattices in a rational way via self-assembly," said Oleg Gang, a physicist
who led this research at the Center for Functional Nanomaterials (CFN) at
Brookhaven Lab in collaboration with scientists from Stony Brook University,
Wesleyan University, and Nagoya University in Japan.
Brookhaven Lab
Center for Functional Nanomaterials (CFN) scientists Kevin Yager, Huolin Xin,
Wenyan Liu
(seated), Alex Tkachenko (back), and Oleg Gang with a sample of gold
nanoparticle
superlattices
linked up by using fabricated DNA as a building material. The computer screen
shows
the resulting
simple-FCC (left) and diamond (right) crystal lattices formed by the
nanoparticles,
as revealed by
cryo scanning transmission electron microscopy at the CFN.
The scientists employed a technique developed by Gang that
uses fabricated DNA as a building material to organize nanoparticles into 3D
spatial arrangements. They used ropelike bundles of double-helix DNA to create
rigid, three-dimensional frames, and added dangling bits of single-stranded DNA
to bind particles coated with complementary DNA strands.
"We're using precisely shaped DNA constructs made as a
scaffold and single-stranded DNA tethers as a programmable glue that matches up
particles according to the pairing mechanism of the genetic code—A binds with
T, G binds with C," said Wenyan Liu of the CFN, the lead author on the
paper. "These molecular constructs are building blocks for creating crystalline
lattices made of nanoparticles."