Coated specks form nano building blocks
By Eric Smalley, Technology Research NewsCovering tiny bits of metal and semiconductor with plastic could be the nanotechnology equivalent of shaping clay into bricks, a development that sets the stage for building microscopic devices and structures piece by piece.
Ordinarily, microscopic particles over 10 nanometers in size are difficult to work with because they tend to clump together.
Researchers at Purdue University have found a way around this problem by coating nanoparticles with molecules called resorcinarenes. The resorcinarenes have bowl-shaped heads, allowing them to adhere readily to the surfaces of nanoparticles, said Alexander Wei, assistant professor of chemistry.
The resorcinarenes heads "almost act like suction pads," he said. The resorcinarenes’ tails are loose strands that the researchers can make bond to each other, forming a web around each nanoparticle.
"We're right now working on making assemblies of 20-, 30-, 40-nanometer particles with these resorcinarene coatings around them," said Wei.
Other approaches to encapsulating nanoparticles have a significant impact on the their physical properties and stability, said Peidong Yang, assistant professor of chemistry at the University of California at Berkeley. But Wei’s approach "successfully circumvents these problems," he said.
As researchers begin to make nanoscale devices, processing technologies like nanoparticle coating are going to play an important role, Wei said. Coating nanoparticles "has definitely expanded our scope to 40-nanometer particles at least. How much further out we can go than that I'm not sure," he said.
The resorcinarene-coated nanoparticles could also be used to make materials with tailored physical properties, Wei said. For example, "if you get particles which are too small they don't respond to a magnet at room temperature. The size domain is very important in a lot of these physical properties," he said.
The coated nanoparticles could also be used to deliver drugs because other molecules can be tightly bonded to the resorcinarene coating, Wei said. For example, cancer-fighting drugs could be adhered to coated magnetic particles which could then be drawn to tumors by carefully positioned magnets, he said.
This type of application could be achieved in one to two years, Wei said.
The research was funded by the National Science Foundation and Research Corporation, a nonprofit foundation that funds basic research. Wei presented his work in August at the American Chemical Society's national meeting in Washington, D.C.
Timeline: 1-2 years
Funding: Government, Private
TRN Categories: Semiconductors and Materials; Nanotechnology
Story Type: News
Related Elements: None
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September 27, 2000
Page One
Ants solve tough problems
Camera gets all the exposure
Coated specks form nano building blocks
Sturdy virus makes tiny container
Freezing speeds rapid prototyping
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