Chemists create a better artificial nose to sniff out explosives and sour milk

Stanford chemists create fluorescent sensors on synthetic DNA to identify a large range of vapors.

I recently wrote about an electronic nose that can detect cancer . Well, Stanford chemists have created an e-nose that has far more applications than that. This artificial nostril can sniff out anything from sour milk to explosives .

Unlike traditional sensors that can only identify one molecule, the fluorescent sensors change color when organic vapors are in the air.

The thing is, the researchers aren't using honeybees to do the dirty work — they're actually making their own sensor from scratch using artificial DNA.

By tacking on fluorescent compounds on to the ends of the DNA strand, the sensors could sniff out way more compounds than optical sensors.

"We were blown away by how strong the color changes were," Stanford chemist Eric Kool said in a statement. "One of the surprising findings was that we could tell the difference between four different organic vapors with just one sensor, because it would turn different colors with different vapors."

The sensors were made with the same technology used to synthesized DNA molecules. With seven possible fluorescent bases to replace the normal four base pairs, the researchers came up with 2,401 possible combinations.

When the sensors were tested against four different vapors — like shoe polish, mold found in food, and yes, even explosives — the researchers found that the sensors changed color and realized the color change depended on the DNA sequence.

Imagine if the sensors could be made on plastic and you could identify the color changes with your naked eye.

In a statement, Kool said, "You could hold a black light over the sensor and read the response. Then you could match up the color of the sensor with a key of some sort and say, 'Ah, this sensor best compares with this color on the key – this milk is about to go sour.'"

Until then, the sensors will need to be portable with some sort of fluorescence microscope attached.

Imagine if you could stack a set of a 100 sensors together, think about how many different kinds of vapors it could sniff out.

But before this artificial nose makes its way out of the lab, the researchers need to figure out how small of a trace these sensors can actually detect.

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