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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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A Golden Way to Detect DNA
21 August 1997 8:30 pm
Chemists have constructed a sensor, made from a web of DNA and gold particles, that turns from red to blue when it detects a precise strand of DNA. This easy-to-read color change, described in tomorrow's Science, could lead to simple and cheap detectors of pathogens for use everywhere from doctors' offices to the battlefield.
To create the new sensors, a team led by chemists Chad Mirkin and Robert Letsinger of Northwestern University in Evanston, Illinois, started with two batches of DNA strands, which act as probes. Each probe sequence was complementary to half of the sequence of a third strand, the "target" strand that the sensor is designed to detect. The researchers then attached small gold-binding organic groups called thiols to the two sets of DNA probes and mixed each set with tiny gold nanoparticles, resulting in fuzzy gold particles coated with dozens of DNA strands each.
Next, the researchers combined the two sets of DNA-coated particles with the target DNA. The result: the first probe linked to half of the target DNA strand, the second probe to the other half, causing the target strand to bridge the two probes. Repeated millions of times, the process glued the nanoparticles together in a three-dimensional web. And the formation of this web changed the electronic behavior of the particles, producing a color change from red to blue.
"It's really marvelous," says Paul Alivisatos, a University of California, Berkeley, chemist, who works in this field. Because the probe strands can be tailor-made, the sensor can be designed to detect any DNA sequence. Mirkin believes that such a cheap and simple DNA detector system could prove useful for everyone from doctors quickly testing patients for infections at the bedside to soldiers scanning for biological warfare agents on the battlefield.
Equally important, Mirkin and others say, the nanoparticle sensor is a proof-of-principle for a strategy for exploiting the talents of DNA to organize nanoparticles into precisely structured devices. Because of DNA's ability to recognize and bind specific sequences, it could direct the assembly of various inorganic nanoparticles into ultra-small electronic circuits. Such circuits would be many times smaller than those housed by the millions on semiconductor chips, which are reaching a practical limit of miniaturization.