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Silver nanoparticles may lead to a host of innovative applications | A team of scientists has introduced a new method to deterministically and precisely position silver nanoparticles onto self-assembling DNA scaffolds, which could lead to a new generation of microelectronics, semiconductors, biological and chemical sensing
devices. In the new research, Hao Yan and Yan Liu , professors at the Biodesign
Institute's Center for Single Molecule Biophysics and their collaborators used
a long single-strand of DNA , which had been folded into a triangular building
platform through a process known as DNA origami. This architectural foundation
was then 'decorated' with one, two or three silver nanoparticles, which self-assembled
at pre-determined locations on the DNA nanostructure. The group's experimental
results, which appear in the advanced online edition of the journal Angewandte
Chemie , demonstrate for the first time the viability of using silver, rather
than the gold nanoparticles traditionally applied to DNA -tile or origami based
architectures. One of many applications for DNA scaffolds studded with nanoparticles
is to perform precise sensing operations at the molecular scale. Sensitive detection
of single molecules with high specificity is of great scientific interest for
chemists, biologists, pharmacologists, medical researchers and those involved
in environmental areas where trace analysis is required. The detailed study of
human genes is but one area where improved single-molecule detection could be
of enormous benefit. In their current effort, the group sought to exploit the
properties of the silver nanoparticles to increase the surface plasmon resonance
- a vibration of electrons that can give researchers clues regarding the molecular
nature of the sample they are studying. "Theoretically, people predicted that
a local surface plasmon resonance can be much stronger if you use silver particles
compared to gold," said Yan. These locally enhanced areas between nanoparticles
are referred to as electrical hot spots. The group however, had to overcome significant
obstacles to the use of silver nanoparticles. Silver tends to be much less stable
than gold and can easily oxidize in its normal state. To counter this tendency,
Yan and Liu's team attached multiple sulfur atoms to the backbone of the DNA strand
used to make the platform for the nanoparticles. Each silver nanoparticle is then
firmly held in place by nine sulfur atoms, once it is mounted on the DNA origami
shape. The new study paves the way for creating a more functional DNA architecture.
"I believe this work will open doors to implement and study distance-dependent
plasmonic interaction between noble nanoparticles at the single particle level,"
Yan said, adding that the first critical steps to creating hierarchically organized
silver nanoparticle structures have now been taken.
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