311_Star of David molecule.
A three-dimensional cage-shaped, artificial nanoparticle that looks from above
like a six-pointed Star of David has been created by Hebrew University of
Jerusalem researchers who believe that it could eventually lead to better
glucose sensors to diagnose diabetes or a more efficient catalyst using sunlight
to turn water into hydrogen for clean fuel.
The achievement by Prof. Uri
Banin and Canadian postdoctoral student Dr. Janet Macdonald is an advance
because while there are soccer-ballshaped molecules, they are so tiny that they
cannot hold other things.
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Nanometers are one-billionth of a meter in
“We created a new particle combining a semiconductor [copper
sulfide] and a metal [ruthenium] with the characteristics of each appearing in
the new nanoparticle,” Banin said.
The particles are nano-sized,
hexagonal crystals, each with a tiny metal frame wrapping around and encasing
them just like a bird’s cage, but 100 million times smaller. Because the
nanocage is hexagonal, when looked at from above, the images appear as Stars of
David. No one had ever seen hybrid nanoparticles form with such a cage structure
Banin and Macdonald – who worked with Israeli post-doctoral
student Dr. Maya Bar Sadan and Dr.
Lothar Houben of the Ernst Ruska
Center for Microscopy and Spectroscopy with Electrons in Juelich, Germany –
published details of their work Sunday evening in the latest (October) issue of
the prestigious journal Nature Materials.
The new star-shaped particles,
10,000 times smaller than the width of a human hair, are very different from
existing nanoparticles in which one material encapsulates the other.
they saw in electron microscope images were particles with surprising striped
patterns and six-pointed star shapes.
Banin, the Alfred and Erica Larisch
Memorial Professor and the director of HU’s Harvey M. Kruger Family Center for
Nanoscience and Nanotechnology, said he and Macdonald worked on the project for
“It took a long time to repeat the accomplishment, understand
how it worked and think of possible ways to implement it,” he said.
next hurdle was figuring out the three-dimensional shape of the particles that
could give such images.
The mystery took months to solve and confirm,
with help from the German team.
They believe their work greatly
contributes to scientific understanding of how hybrid nanoparticles combining
two or more different materials on the same particle form. Although they are not
yet at the stage of application and have not consulted a diabetes expert, they
understood that the cage-like structure could be used as a glucose sensor for
the blood to detect diabetes, as the resulting nanoparticle has a longer shelf
life and is more stable than existing sensors.
As it is not organic, “it
may be a solution for the instability problem.
There are no other
inorganic cases of this size in the scientific literature,” he added.
researchers coated an electrode with the nanocages and proved that it is
possible to detect with the new device minute quantities of hydrogen peroxide.
Uncaged copper sulfide particles alone were not sensitive, and amazingly, the
addition of the metal frame boosted the electrical signal of detection 200
Sensing peroxide is a first step toward new and better sensors for
glucose, which has important medical implications, including for
diagnostics, Banin said.
The cage-like receptacle could be used to change
light to chemical energy, even efficiently separating hydrogen out of
produce clean fuel instead of petroleum, Banin said.
found that the nanoparticle could be created with other semiconductors
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