Particle Resembling Star-of-David Discovered

Published: September 21st 2010
in News » Israel

Star of David particle, Science Daily

A nano-particle resembling the Star of David has been discovered by researchers at the Hebrew University of Jerusalem, Science Daily reported.


The discovery, the researchers say, could lead to new ways for identifying glucose in the diagnosis of diabetes, and even provide a catalyst to capture the sun's energy and turn it into clean fuel.


According to the researchers, these findings also contribute to the understanding of how hybrid nano-particles form in the first place.


Hybrid nano-particles are systems which combine two or more different materials on the same particle, where the combination provides multiple functions to the particle. The discovery of the Hebrew University scientists is described in an article published now online and in the October 2010 issue of the journal Nature Materials.


The new Star-of-David-shaped particles, sized at 10,000 times smaller than the width of a human hair, were discovered by the research group of Uri Banin, the Alfred and Erica Larisch Memorial Professor and the director of the Harvey M. Kruger Family Center for Nanoscience and Nanotechnology at Jerusalem’s Hebrew University.


The researchers have been working to develop new nano-particles made of two kinds of materials joined together. Thus far, scientists have only found nano-particles in which one material encapsulates the other (resembling an egg and a yolk), or where an island of one material forms on the other (much like the head of the match on a match-stick), Science Daily reported.


This was not the case, however, with the Star-of-David shapes.


Dr. Janet Macdonald, a researcher in Banin's group, worked on synthesizing nano-particles combining copper sulfide with ruthenium, each possessing unique properties. But instead of the expected egg and yolk formation, electron microscopes revealed particles in surprising striped patterns and Star-of-David shapes.


The researchers generated a three-dimensional image of the nano-particles using a powerful electron microscope and found that the Stars-of-David are actually "nano-cages." The particles are nano-sized crystals shaped like hexagons, each with a tiny metal frame wrapping around and encasing them like a bird's cage, but 100 million times smaller, said Science Daily.


And because the nano-cage is hexagon-shaped, when looking at pictures of them from above, they appear as Stars-of-David. No one had ever seen hybrid nano-particles form with such a cage structure before.


Exploration into the possible uses for the nano Stars-of-David has just begun, and already research has proven that they are not just beautiful; the unique composition and the cage shape, it turns out, makes them very useful indeed.


The first application demonstrated was in the use of the nano-cages as sensors that are able to detect minute quantities of hydrogen peroxide. The particles alone without the cage were not sensitive, and remarkably, the addition of the metal frame boosted the electrical signal of detection 200-fold.


The implication for this is that sensing peroxide is a first step towards sensing glucose, which can aid with diabetes diagnostics.


But Banin and his team of researchers have even farther-reaching aspirations for the nano Stars-of-David: testing these materials as sensors for other medical and environmental uses, and investigating if they can be used as photocatalysts for using sunlight to generate "green fuel."

Related articles: (electron microscope, Star of David, particle, Science Daily)
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