Worth their weight

Nanoscience research under way at Purdue University may provide a way to connect microchips with organic molecules. The resulting biosensors could be used in semiconductors that detect nerve gas and other biohazards. The research also promises a low-cost method of placing nanoparticles of gold and other precious metals on silicon and GaAs materials.

A team led by Jillian Buriak, associate professor of chemistry in Purdue's School of Science, has developed a technique to deposit nanoparticles of high-purity metals in double layers. Buriak's group dissolves low-purity metal salts in liquid at just the concentration needed to form nanoparticles. "All you need to do to form nanoparticles is dip the semiconductor into the solution and wait," says Lon Porter, a chemistry graduate student in the research group. "Though you begin with a solution worth less than the change in your pocket, you still end up with a layer of gold nanoparticles on the silicon that has the same purity as gold bullion."

Over time, the particles grow and cover the base with a bumpy coating. As a result, a rough surface develops that will accept a second set of molecules on top of the gold. If they're organic molecules, they could be chosen especially to detect the presence of nerve gas, for instance.

"Nanoparticles could be the bridge that we need to make computers interface with the biological world," Porter predicts.