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Scientists use engineered spinach to detect explosive chemicals underground

Plant-to-human communication
Popeye understood the power of spinach but he probably didn’t expect this: scientists have engineered leafy greens to help detect chemicals underground.

A team of MIT researchers embedded spinach plants with nanotubes that enable the plants to sense different chemicals in their environment and transmit signals relating to those chemicals. When the chemicals are detected, the tubes emit a fluorescent signal that can be picked up by an infrared camera.

“The fact is that plants are enormous sources of information.”

The process of engineering these electronic system into plants is known as “plant nanobionics” and it may give plants new purpose. The study was published yesterday in Nature Materials.

“When we think of plants, we tend to think of them as being essentially static,” lead researcher Min Hao Wong told Digital Trends. “The fact is that plants are enormous sources of information. They interact constantly with the environment that we live in, absorbing and accumulating various particulates and compounds, and responding to changes in temperature or humidity.”

Wong and his team (including MIT’s Michael Strano and University of California at Riverside’s Juan Pablo Giraldo, both of whom helped pioneer plant nanobionics) want to change the way we look at plants. Their goal is to demonstrate that plants can store valuable information about their environment — such a nutrients and groundwater quality — and that humans can access this data with a little engineering and ingenuity.

“In this role, plants serve as environmentally friendly, and net zero carbon, sensors of the environment that we live in,” Wong said. Plus, plants are self-powered, practically carbon-negative, and more pleasing to the eye than mechanical instruments.

In the recent study, the researchers embedded carbon nanotubes into spinach leaves. When the plant absorbs water, the nanotubes can detect a range of chemicals, including the nitroaromatic compounds that are often used in explosives. The nanotubes emit a fluorescent light when a compound is detected and a cheap infrared camera, such as those found in most smartphones, can pick up the signal. A simple device such as a Raspberry Pi can then email an alert to a user.

“On explosives, 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,” Wong said. “Such plants could be used to monitor groundwater seepage from buried munitions or waste that contains nitro-aromatics.” The system can also be used in agriculture to monitor the health of the plant itself, Wong added, by detecting pests and pathogens.

Strano and Giraldo first demonstrated plant nanobionics two years ago when they embedded carbon nanotubes into the chloroplast of leaves, allowing them to capture 30 percent more light energy.

Although the electronics used in the recent study are relatively low cost (a Raspberry Pi computer costs a mere $35), Wong admitted more work is needed to lower costs further and investigate environmental effects. He has founded a startup, Plantea, to work toward commercializing the technology.

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