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Nanotube Sensors Sniff Out Spoiling Meat

Materials: Fluorescent perylene diimide tubes dim when they detect amines

by Matt Davenport
November 16, 2015 | A version of this story appeared in Volume 93, Issue 45

Fluorescent nanotubes now can serve as a nose for rotting meat thanks to researchers led by Yanke Che of the Key Laboratory of Photochemistry at the Chinese Academy of Sciences (ACS Sens. 2015, DOI: 10.1021/acssensors.5b00040). Earlier this year, the team developed brightly fluorescing, chiral nanotubes made from asymmetric perylene diimide molecules. The researchers then discovered that they could make thin mats of these tubes by dropping ethanol suspensions of the tubes onto Teflon substrates. Once dry, these tubular films provide large surface areas that can sense amines exuded by spoiling meat, including putrescine and cadaverine. When these pungent amines waft into a film, they transfer electrons to the nanotubes, causing the nanotubes’ fluorescence to drop. In tests using pork, fish, shrimp, and chicken, the team demonstrated that the films could detect chemical signs of spoilage at parts-per-billion levels. Although other instruments can achieve this sensitivity, they are large and complicated, says Otto S. Wolfbeis of the University of Regensburg, who was not involved in the study. “This assay, in essence, requires a sensor film, a UV lamp, and some training,” he says. “This method represents a major leap forward.”

A structure of a perylene diimide molecule.
Asymmetric perylene diimide molecules, such as the one shown here, assemble into chiral nanotubes. Researchers can also make tubes using this molecule’s mirror image.
A scheme showing how a nanotube device works.
Credit: ACS Sens.
Fluorescent nanotubes dim when they detect amines from spoiled meat. The outer diameter of a tube is about 17 nm.


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