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Bacteria, templates and gold islands.

Bacteria, templates and gold islands

Sometimes it's handy to get nature to do some of the work for you, especially when the work involves the delicate task of creating regularly spaced, nanometer-sized holes in a thin metal film. The protein molecules that make up the outer wall of the bacterium Sulfolobus acidocaldarius assemble themselves into a two-dimensional layer with an array of holes that allow materials to pass in and out. When deposited on a smooth, graphite surface, such a protein layer (essentially a two-dimensional, crystalline array) can serve as a template. By coating the protein layer with a thin metal film, then using a technique known as ion milling, researchers can selectively remove the metal from spots corresponding to the holes in the protein layer.

It's a simple, inexpensive means of patterning surfaces periodically on a nanometer scale, say Kenneth Douglas and Noel A. Clark of the University of Colorado in Boulder and Kenneth J. Rothschild of Boston University, who developed the technique. The resulting metal screen, with holes about 14 nanometers in diameter arranged in a triangular lattice, measures just a few nanometers thick.

The group is now studying the possibility of fabricating unique composite materials by letting the holes in such a metal grid selectively capture biological molecules such as the protein ferritin, which fit snugly into the holes and bind to the underlying graphite surface. It may also be possible to create arrays of gold islands by letting tiny gold particles settle into the holes. These structures offer exciting possibilities for making novel chemical, electronic or optically active devices such as sensors, the researchers say.
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Title Annotation:using bacteria to make holes in thin metal film
Author:Peterson, Ivars
Publication:Science News
Date:Mar 24, 1990
Previous Article:Chaotic systems that stay in step.
Next Article:Meteorites from the moon's lava plains.

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