Researchers fill virus with metal

One way to construct materials atom by atom is to conscript machinery nature has already devised.

Scientists have methods of making round particles that are as small as one nanometer, which is the span of 10 hydrogen atoms. But making more complicated shapes is more difficult.

Researchers from the University of Bristol in England, Vanderbilt University, and the University of Maryland have found that they can fill or coat a long, cylindrical tobacco virus with metal particles.

The method could eventually be used to manufacture structures like metal nanowires that could be used in electronics or optics devices, according to the researchers.

The researchers mixed the 4- by 300-nanometer virus with gold, silver and platinum salts. In an acidic pH solution, negatively-charged metal salts reacted with viral amino acids to cause nanoparticles to align on the outer surface of the virus. In a neutral pH solution, positively-charged salts passed through the viruses' protein coats, causing metal nanoparticles to align inside the viruses.

The researchers showed that mutating the amino acids affects where the metal particles deposit.

The method to be used practically in 10 to 20 years, according to the researchers. The work appeared in the March 12, 2003 issue of Nano Letters.