May 23, 2003 

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Bio Detector (video)
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Interviewee: Jillian Buriak, Purdue University.

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Produced by Ann Marie Cunningham

Copyright © ScienCentral, Inc., with additional footage courtesy Purdue University.

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Next time you’re struggling with computer cables, consider this: according to a report in the journal Nano Letters, scientists are working on a way to connect a computer to living things.

Why? As this ScienCentral News video reports, the effort could help protect us from bioterror.

Fighting hazards from a computer

If we are attacked with nerve gas or anthrax, we’ll need to know what’s coming our way as quickly as possible. Nanotechnologists are working on new sensors that are both small and sensitive enough to work anywhere that we are threatened with biological or chemical weapons.

At Purdue University, chemist Jillian Buriak has come up with a detection lab on a chip. She uses extremely tiny pieces of gold that can connect from a computer to natural sensors found in living cells to pick up traces of biochemical agents.

To make the sensor on a chip, Buriak starts with "nanoparticles" of gold. A nanoparticle is only a few atoms wide, many thousands of times smaller than the width of a human hair (80,000 nanometers wide). Gold was her first choice, because it doesn’t rust, giving a chip a pristine surface. Gold also conducts electricity very well.

In Buriak’s lab, her team dips metal chips into a solution of gold nanoparticles. Over time, gold fragments form a bumpy coating on a chip. The longer a chip spends in solution, the rougher its surface becomes. This surface is key to Buriak’s next step: attaching to the chip organic molecules—the building blocks of living cells—that react in the presence of chemical or biological agents.

The new bumpy coating means that the chip’s surface has grown considerably larger. Buriak’s graduate student and co-author, Lon A. Porter, Jr., compares the chip’s altered surface to our brains: "Your brain packs a lot of surface area into the limited space inside your skull by folding in on itself many times."

The chip’s rough surfaces offer plenty of nooks and crannies where molecules can cling securely. The gold also lets electric signals flow freely to and from the molecules.

From a computer loaded with Buriak’s new chip, the molecules can be told to sniff chemical or biological toxins out in the open, just as they do inside living cells. If a molecule detects something dangerous, it reacts chemically, triggering a small electrical change. That sends an electronic signal through the gold nanoparticles. The molecule’s signal then shows up on the computer’s monitor.

Buriak predicts that "nanoparticles could be the bridge we need to help computers interact with the biological world." Because she and her researchers also have come up with ways to deposit gold nanoparticles on a chip in specific patterns, they believe that their techniques have commercial use. They could result in more efficient semi-conductors—and therefore computers that can work faster on less power. They also would cost less: Buriak’s technique requires a very inexpensive form of gold that in the form of her solution, is worth only pennies.

by Ann Marie Cunningham

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