Los Alamos National Laboratory

Imagine a piece of metal 30,000 times thinner than one of the hairs on your head. Mixed with a little protein from bee venom, that microscopic filament becomes the most powerful explosives-detection system in history, able to detect a single molecule of dangerous chemicals.

Now imagine having that in an airport. No need for taking a pornographic photograph or having your genitals massaged by the Transportation Security Agency. And a nanotechnology specialist may have hastened that happy day for homeland security.

Michael Strano, an associate professor of chemical engineering at the Massachusetts Institute of Technology, spent the past two years testing out the boundaries of nanotech in explosives detection. For less than $200,000, he took it practically to the atomic limit. "There's no further improvement in the sensor part you can get," Strano tells Wired. "It's the last word in sensors."

Some of his colleagues aren't quite so sure. Strano's system is promising, they say. But they have questions about bringing Strano's sensor into the field.

The science behind the Strano's sensor is complex. But here's the simplest way of breaking it down. Put bee venom on a carbon rod and you've got yourself a sensor.

Believe it or not, bees are powerful bomb sleuths. That's why Darpa wanted to enlist them to find explosives, landmines and "odors of interest" in the early 2000s. As it turns out, inside of every bee sting is a small fragment of a protein called a peptide that has an uncanny property.

"When it wraps around a small wire, that allows it to recognise 'nitro-aromatics'" Strano explains, the chemical class of explosives like TNT. That wire is a carbon nanotube, a mere one atom thick.

Put that against a nitro-aromatic treated with the bee peptide, and take a look through a near-infrared microscope. "The light from the carbon nanotube will fluoresce -- so red that your eye can't see it," Strano says. "What you'd see in the microscope is: The nanotube would flicker off and on." A single molecule of the explosive material would set off the sensor.

Strano and his team published their work on Tuesday in the Proceedings of the National Academy of Sciences.

The ion-mobility spectrometers currently used to spot bombs in US airports are "poor machines" says Ray von Wandruszka, chairman of the chemistry department at the University of Idaho, who's worked on atmospheric explosive detection since 1989. The spectrometers typically detect chemicals in the "low parts per billion" range. Strano's sensor would be vastly more sensitive.

If it works, that is.


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