Two items here on the manipulation and creation of engineered
nanoparticles of gold. Read and wonder. I am expecting a lot out of
this research, comparable to the output related to the work on
graphene.
As we follow this, I remind readers of what has been called monatomic
gold. Folks playing with this stuff, were playing with fire, and
making astounding claims with little convincing support. From this
is is easy to see why such efforts are worthy.
It is all early days yet I think this work will provide momentum to
charge ahead. Recall two years ago, a physicist injected 20nm
particles into mouse bloodstream and then when they accumulated
naturally inside cancer cells, he applied radio-wave heating to kill
those cells. This is nano surgery at its best.
This cured the mice.
University of Illinois
chemists found that DNA can shape gold nanoparticle growth similarly
to the way it shapes protein synthesis, with different letters of the
genetic code producing gold circles, stars and hexagons. (Credit: Li
Huey Tan, Zidong Wang and Yi Lu)
ScienceDaily (Aug. 8,
2012) — DNA holds the genetic code for all sorts of biological
molecules and traits. But University of Illinois researchers have
found that DNA's code can similarly shape metallic structures.
The team found that
DNA segments can direct the shape of gold nanoparticles -- tiny
gold crystals that have many applications in medicine, electronics
and catalysis. Led by Yi Lu, the Schenck Professor of Chemistry
at the U. of I., the team published its surprising findings in the
journal Angewandte Chemie.
"DNA-encoded
nanoparticle synthesis can provide us a facile but novel way to
produce nanoparticles with predictable shape and properties," Lu
said. "Such a discovery has potential impacts in
bio-nanotechnology and applications in our everyday lives such as
catalysis, sensing, imaging and medicine."
Gold nanoparticles
have wide applications in both biology and materials science thanks
to their unique physicochemical properties. Properties of a gold
nanoparticle are largely determined by its shape and size, so it is
critical to be able to tailor the properties of a nanoparticle for a
specific application.
"We wondered
whether different combinations of DNA sequences could constitute
'genetic codes' to direct the nanomaterial synthesis in a way similar
to their direction of protein synthesis," said Zidong Wang, a
recent graduate of Lu's group and the first author of the paper.
Gold nanoparticles are
made by sewing tiny gold seeds in a solution of gold salt. Particles
grow as gold in the salt solution deposits onto the seeds. Lu's group
incubated the gold seeds with short segments of DNA before adding
the salt solution, causing the particles to grow into various shapes
determined by the genetic code of the DNA.
The DNA alphabet
comprises four letters: A, T, G and C. The term genetic code refers
to the sequence of these letters, called bases. The four bases and
their combinations can bind differently with facets of gold nanoseeds
and direct the nanoseeds' growth pathways, resulting in different
shapes.
In their experiments,
the researchers found that strands of repeating A's produced rough,
round gold particles; T's, stars; C's, round, flat discs; G's,
hexagons. Then the group tested DNA strands that were a combination
of two bases, for example, 10 T's and 20 A's. They found that many of
the bases compete with each other resulting in intermediate shapes,
although A dominates over T.
Next, the researchers
plan to investigate exactly how DNA codes direct nanoparticle growth.
They also plan to apply their method to synthesize other types of
nanomaterials with novel applications.
The National Science
Foundation supported this work.
Scientists' Gold Discovery Sheds Light On Catalysis
ScienceDaily (Aug. 10,
2012) — A physicist at the University of York has played a key
role in international research which has made an important advance in
establishing the catalytic properties of gold at a nano level.
Dr Keith McKenna was
part of a research team which discovered that the catalytic
activity of nanoporous gold (NPG) originates from high concentrations
of surface defects present within its complex three-dimensional
structure.
The research, which is
published online in Nature Materials, has the potential to
assist in the development of more efficient and durable catalytic
converters and fuel cells because nanoporous gold is a catalytic
agent for oxidising carbon monoxide.
Bulk gold -- the sort
used in watches and jewellery -- is inert but nanoporous gold
possesses high catalytic activity towards oxidation reactions. The
research team, which also included scientists from Japan, China and
the USA, discovered, that this activity can be identified with
surface defects found within its complex nanoporous structure. While
nanoporous gold exhibits comparable activity to nanoparticulate gold,
it is considerably more stable making it attractive for the
development of catalysts with high performance and long lifetimes.
They created NPG by
immersing an alloy of gold and silver in a chemical solution which
removed the latter metal to create a porous atomic structure. Then,
using transmission electron microscopy, they were able to detect
evidence that the surface defects on the NPG were active sites for
catalysis and the residual silver made them substantially more
stable.
Dr McKenna, of the
Department of Physics at the University of York, said: "Unlike
gold nanoparticles, dealloyed NPG is unsupported so we are able to
monitor its catalytic activity more accurately. We found that there
are many surface defects present within the complex structure of NPG
which are responsible for the high catalytic activity.
"This work has
given us a greater understanding of the catalytic mechanisms of NPG
which will, in turn, shed light on the mechanisms of gold catalysis
more broadly."
The research also
involved the WPI Advanced Institute for Materials Research, Tohoku
University, Japan; Ectopia Science Institute, Nagoya University,
Japan; Department of Materials Science and Engineering, Johns Hopkins
University, USA, and School of Materials Science and Engineering,
Shanghai Jiao Tong University, China.
The research was
sponsored by JST-PRESTO, JST-CREST and the Sekisui research fund.
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