Star of David, the science way

By Jennifer Lipman
September 22, 2010


As anyone who knows me can testify, I'm no scientist.

Still, I thought this particular finding by academics at Hebrew University in Jerusalem was rather lovely.

Apparently, it’s a new type of nanoparticle. Certainly more interesting than my lasting memory of biology class - looking at red onion through a microscope.



Sun, 09/26/2010 - 23:04

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from "nature materials" 19/9/2010

We report the integration of the two powerful concepts of cages and hybrid nanoparticles.
A previously unknown edge growth mechanism has led to a new type of cage-structured hybrid metal–semiconductor nanoparticle; a ruthenium cage was grown selectively on the edges of a faceted copper(I) sulphide nanocrystal, contrary to the more commonly observed facet and island growth modes of other hybrids7, 12, 13, 14, 15.
The cage motif was extended by exploiting the open frame to achieve empty cages and cages containing other semiconductors.
Such previously unknown nano-inorganic cage structures with variable cores and metal frames manifest new chemical, optical and electronic properties and demonstrate possibilities for uses in electrocatalysis.

(and there's lots of pretty pictures following the article)


They 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 were previous existing soccer-ball-shaped molecules, they are so tiny that they cannot hold other things.

The new star-shaped particles, with sizes 10,000 times smaller than the width of a human hair, is very different from existing nanoparticles 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). Instead of viewing ruthenium islands on the seed particles, what they saw in electron microscope images were particles with surprising striped patterns and six-pointed star shapes.

Because the resulting nanoparticle is not organic it has a longer shelf life …

Uncaged copper sulfide particles alone were not sensitive, and amazingly, the addition of the metal frame boosted the electrical signal of detection 200 times. Sensing peroxide is a first step towards new and better sensors for glucose, which has important medical implications, including for diabetes diagnostics, Banin said.

The cage-like receptacle could be used to change light to chemical energy, even efficiently separating hydrogen out of water to produce clean fuel instead of petroleum, Banin said. The researchers found that the nanoparticle could be created with other semiconductors as well.


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