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Enzymes under glass.

Because enzymes bind to specific substances, they show promise as sensors that can detect minute amounts of chemicals. To take advantage of the sensitivity, of enzymes, scientists have embedded them in glass without destroying their activity. The clear glass traps the enzymes byt lets in small molecules through its pores. If these molecules react with the enzymes, the glass changes color.

To make prototype sensors, chemist Stacey A. Yamanaka and her colleagues at the University of California, Los Angeles, modified a process called sol-gel synthesis. They start with a solution of water, methanol and a silicon compound and mix in acid. Typically, these ingredients form a silicon-oxygen compound that dries down to a clear, rigid glass. The Los Angeles group made the process hospitable to enzymes by adding buffer to the solution, reducing the amount of alcohol and keeping the resulting glass cool.

In early experiments, the researchers trapped one kind of enzyme throughouts small cubes. Now they have embedded two kinds of enzymes -- one that breaks down glucose and one that destroys hydrogen peroxide -- plus dye precursors (to make the glass turn color) all in the sam cube. When they dipped these cubes into a solution containing glucose, "the samples turned red," Yamanaka reports. For the red to appear, one enzymes had to break glucose into gluconic acid and hydrogen peroxide. These products then had to react with the second enzymes and the dye precursors. "By utilizing the specific binding properties and the molecular recognition properties of these [enzymes], there's the hope of making molecules biosensors," she concludes.
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Title Annotation:sensor research
Author:Pennisi, Elizabeth
Publication:Science News
Article Type:Brief Article
Date:May 9, 1992
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