When the police use dogs to sniff for explosives or drugs, they are taking advantage of the complex structure of a dog's nose. Dogs (and other animals) have hundreds of millions of tiny fibers in their noses, and these fibers contain receptors that identify substances. The large number of fibers and the way they are arranged in the nasal cavity forms a large internal field that enables very high sensitivity, even to low concentrations of substances.

Hitherto, despite numerous attempts, no one had ever succeeded in reproducing this complex structure artificially. But now, Prof. Ehud Gazit of Tel Aviv University's faculty of life sciences has found a way to create an artificial structure similar to a dog's nose, using nanotubes with a diameter about one-thousandth the diameter of a human hair. In a few years, he predicted, this nanotechnology could be used, inter alia, to build extremely sensitive detectors that would completely change existing methods of detecting drugs or explosives.

For instance, Gazit said, detectors one meter in size that were capable of scenting explosives from afar could be erected in airports. "It would be a kind of imitation dog's nose, but a nose that scents explosives from kilometers away instead of meters," he said.

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Gazit's research on creating such nanotechnology systems was published last week as the cover story of Nature Nanotechnology, the world's most prestigious journal in the field.

Gazit, 40, has for years studied the creation and arrangement of nanotubes made of simple proteins known as dipeptides, which can easily be manufactured in industrial quantities. The project began in the context of research into Alzheimer's and similar diseases. "When you take a slice of brain from an Alzheimer's patient, you see that small-diameter fibers have formed there," he explained.

Three years ago, after Gazit and his team had managed to create the nanotubes, they were faced with a no less significant problem: How could these tiny components be made to act as the researchers wanted them to do? "In general, we don't have the tools to utilize the potential of nanometric structures," Gazit explained. "They are so small that it is virtually impossible to move them mechanically."

Gazit and his graduate student, Meital Reches, found two solutions. One was a controlled evaporation of the material in which the dipeptides were dissolved, which caused them to align in the same direction. The researchers were thus able to grow a "nanoforest" containing millions of such structures in a single square millimeter. "This was a chance discovery," Gazit said. "We looked through an electron microscope and suddenly saw such a forest."

The second technique involved attaching magnetic nanoparticles to the nanotubes, and then subjecting the nanotubes to an external magnetic field, which caused them to align.

According to Gazit, the fact that the nanotubes can be made to align is tremendously important. Unaligned nanotubes could increase the sensitivity of a detector tenfold, he said, but aligned nanotubes increase the sensitivity by a factor of 100,000 or more. This would enable the detector to detect even a single molecule of explosives, rather than being blind to a quantity of less than 1,000 molecules.

Gazit firmly believes that within the next decade, nanotechnology will burst the bounds of the laboratory and start affecting our daily lives. "Currently, we're just creating the building blocks. But in the future, this will have a great many uses," he said