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Spinach: The Superfood That Could Help Detect Bombs

Now more than Popeye’s favorite food, carbon nanotubes are turning the leafy green into a bomb detector

(Christine Daniloff/MIT)
smithsonian.com

The benefits of spinach are almost too numerous to list. It’s full of nutrients, including vitamin K, vitamin A, and folic acid. It’s got fiber, omega-3 fatty acids. And it's edible cooked or raw, in a salad or a smoothie. But one unexpected benefit? New spinach engineered with microscopic carbon nanotubes is helping MIT researchers detect explosives like land mines.

The researchers used a technique called vascular infusion to place explosive-sensitive carbon nanotubes into the layers of the plant that perform photosynthesis, according to a press release. If the plant draws up any water containing explosives, the fluorescence of the nanotubes changes, which can be detected by an infrared camera that wirelessly relays the information. The researchers describe the process in a paper recently published in the journal Nature Materials.

Sarah Kaplan at The Washington Post reports that the researchers tested their idea by introducing carbon nanotubes into the spinach plants' water supply. These specially-engineered nanotubes can detect the explosive class of compounds, known as nitroaromatics, which, when present, change the tubes' fluorescence. For comparison, the researchers also embedded nanotubes that do not detect explosives, giving the plants a baseline fluorescence. Within ten minutes the infrared light emitted by the spinach changed, indicating the presence of nitroaromatics.

“These sensors give real-time information from the plant. It is almost like having the plant talk to us about the environment they are in,” Min Hao Wong, graduate student at MIT and lead author of the study,​ says in the press release.

Co-author of the study Michael Strano tells Edd Gent at LiveScience also explains that plants are near perfect environmental monitors. “A plant can monitor its own environment for pest infestations, damage, drought,” he says. “They're very sensitive readers of their own physiology, and we’re interested in extending this approach and tapping into plants’ own complex signaling pathways.”

Explosives aren’t the only thing the nanotubes can detect. They can be tuned to find Sarin gas, hydrogen peroxide and other pollutants. The explosive-detecting spinach is a proof of concept, and the team believes the method could work with many other plants and chemicals.

“Our paper outlines how one could engineer plants like this to detect virtually anything,” Strano tells the BBC. “The plants could be used for defense applications, but also to monitor public spaces for terrorism related activities, since we show both water and airborne detection. Such plants could be used to monitor groundwater seepage from buried munitions or waste that contains nitro-aromatics.”

Raffaele Di Giacomo, nanobionics researcher at ETH Zurich who was not involved in the study, tells Gent that he sees a day when plants in our homes will be able to detect temperature, humidity, oxygen levels and pollutants and send the information directly to our smartphones.

Wong has already started a company called Plantea with hopes to eventually commercialize the technology. 

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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