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Harnessing Nature's Cellular Dynamo


Developments to Watch

HARNESSING NATURE'S CELLULAR DYNAMO

INSPIRED BY PHOTOSYNTHESIS, ENGINEERS LONG AGO devised photovoltaic chips, or solar cells, that convert sunlight into electricity. But plants don't run on electricity. They rely instead on a special kind of chemical energy using ATP (for adenosine triphosphate) to fuel growth and reproduction.

At Arizona State University in Tempe, chemistry professors Thomas and Anna Moore and Devens Gust are pursuing a new approach to artificial photosynthesis--one that comes a lot closer than solar cells to what plants actually do. They devised a membrane that produces ATP when exposed to light. Their feat is featured in the Apr. 2 issue of Nature. The membrane is made from fatty molecules, called lipids, that are infused with synthetic compounds. When these chemicals absorb light, they pump hydrogen ions, or protons, across the membrane and through an enzyme derived from spinach. And this enzyme uses the proton energy to synthesize ATP.

Many hurdles remain before such a device could become useful to industry, including high costs. But someday, a membrane like this could provide energy for the synthesis of drugs or other useful proteins inside artificial cells. "Electrical energy has more than 100 years of history behind it," Thomas Moore points out. Proton-based energy, in contrast, "is still something that's unknown outside of living cells."Neil GrossReturn to top

PAINT THAT SEES RUST BEFORE YOU DO

SPOTTING METAL CORROSION early means that remedial action can be taken before rust can weaken a bridge or disfigure a car. And nowhere is early detection more vital than on aircraft. Now, researchers at Ohio State University have developed a litmus test for structural corrosion--a special paint that visually flags pockets of rust too tiny for the naked eye to spot.

Corrosion normally increases the pH, or reduces the acidity, of the surrounding metal. So Gerald S. Frankel, an associate professor of materials science, blended a paint with phenolphthalein, a chemical that reacts to increases in pH by turning red. The "litmus paint" should be cheaper than the alternative of embedding sensors in a plane's skin. Moreover, because the paint can even detect corrosion lurking in the cracks and crannies between metal panels, it promises to minimize the need to periodically take planes apart to check for corrosion. That's a main reason why the Air Force is funding the research.

So far, though, Frankel and graduate student Jian Zhang have experimented only with transparent paints. Adapting the concept to pigmented paints "presents lots of practical problems," Frankel admits. He expects to solve them, but it will take a while. Until then, the paint could be used on interior surfaces.EDITED BY OTIS PORTReturn to top

EARLY WARNING FOR THE BIG C?

ALTHOUGH SCIENTISTS ARE FURIOUSLY SEARCHING FOR A CURE FOR CANCER, inexpensive tests that detect tumors sooner could provide immense benefits. The sad truth is that in almost half of all cases, by the time people learn that they have cancer, it's too late.

Researchers at Johns Hopkins University's Oncology Center in Baltimore now report preliminary success with a simple saliva test for head and neck cancers. In a report presented to the American Association of Cancer Research meeting on Mar. 29, Dr. David Sidransky said he tried the test on 21 patients already diagnosed with cancer of the mouth or neck. The test was 71% successful in detecting cancer, he said. With 22 tumor-free patients, the test came up 100% negative.

Sidransky's test looks for evidence of genetic mutations produced in the chromosomes of cancer cells. Spotting these markers in a patient's saliva, Sidransky says, could cost as little as $150--and only a few dollars if implemented with microchip-based chemis-try. At that point, oral cancer screening could become routine during dental visits.Catherine ArnstReturn to top


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