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Viruses may help make microchips

LA JOLLA, Calif., Jan. 29 (UPI) -- Viruses with molecules of gold and antibodies studded on their surfaces may one day invade tumors in pinpoint cellular surgery and help assemble electronic wires thinner than visible light wavelengths for handheld supercomputers.

Researchers at Scripps Research Institute in La Jolla, Calif., have discovered a way to attach molecules to the surface of a virus -- tacking on anything from metal to vitamins.

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"We can attach anything we want to the surface of the virus," said researcher Jack Johnson.

Scientists hope to use viruses as microscopic robots with programmable chemistry, genetically modifying the germs to accept different molecule types in patterns on their surfaces.

One particularly tantalizing possibility scientists are investigating on behalf of the U.S. Naval Research Laboratory in Washington is building circuits of electrically conducting molecules on viral surfaces to form molecular computers.

"You can, in principle, determine the type of assembly you get by programming the building blocks," said researcher M.G. Finn.

The scientists experimented with a plant germ known as cowpea mosaic virus, which resembles a spiky soccer ball in shape. The virus, which is completely harmless to humans, is only 30 nanometers in diameter -- more than 30,000 times thinner than a human hair. The viral shell is made of 60 identical proteins and is remarkably stable in terms of temperature and acidity.

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"They're very beautiful structures to look at," Finn said. "What really takes my breath away is how much information and function is encoded into these structures. That kind of information is something we really don't know how to create ourselves yet."

The scientists are taking advantage of more than a billion years of nature's handiwork with their research. They genetically modified the virus, essentially making its interiors and exteriors chemically stickier. So far, the researchers have attached everything from fluorescent dyes and gold clusters to antibodies, sugars and vitamin B to the germ's surfaces.

Finn said up to 60 molecules can be attached to the virus outer surface. It is possible to genetically program the virus to make it differentially sticky -- for instance, the upper half can have metal particles tightly packed onto it while the bottom has antibodies widely spaced apart on it.

"It may be a lot more effective to pack 60 antibodies onto a surface and let them do their work," Finn said in an interview with United Press International.

The viral particles also show the as-yet unexplained ability to spontaneously self-assemble into lines that intersect at right angles on silicon surfaces -- a talent no doubt of interest to the computer industry. If loaded with metal, the viruses could robotically assemble molecular wires.

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"The goal is to give each virus particle a function that would be useful in an electronic circuit," Finn said.

However, molecular electronics may be years away, Finn said. More immediate applications may be in using the viruses to surgically target tumors that leave surrounding cells untouched, with antibodies that latch onto cancer cells studding the outside of the virus and chemotherapy drugs lining the inside of the germ.

The scientists also look forward to using the virus to help examine biochemicals that are previously unviewable.

"I think the work elegantly demonstrates the ability to use viral protein cages as scaffolding for directed chemical reactions," said virologist Mark Young at Montana State University in Bozeman. "This work represents a milestone, since it suggests that assembled virus particles can be treated as chemically reactive surfaces that are potentially available to a broad range of organic and inorganic applications."

The researchers reported their findings in the European scientific journal Angewandte Chemie.

(Reported by Charles Choi in New York.)

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