US researchers transform spinach plants into sensors to detect explosives

Engineers at the Massachusetts Institute of Technology (MIT) in the US have transformed spinach plants into sensors by embedding them with carbon nanotubes to detect explosives.

This demonstration of engineering electronic systems into plants is an approach that the researchers call ‘plant nanobionics.’

As part of the research, spinach plants were modified to detect chemical compounds known as nitroaromatics.

If groundwater sampled by the plant contains one of these chemicals, carbon nanotubes embedded in its leaves release a fluorescent signal, which can be read with an infrared camera connected to a small computer.

MIT chemical engineering professor Michael Strano said: “The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions.”

“This is a novel demonstration of how we have overcome the plant / human communication barrier.”

A new company called Plantea has been started to further develop the technology.

MIT researchers embedded sensors into the plants by performing vascular infusion, which involves applying nanoparticles to the underside of the leaf, and placing the sensors into the mesophyll leaf layer.

"The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions."

Carbon nanotubes that emit a constant fluorescent signal were then embedded to compare the two fluorescent signals, in a bid to determine if the explosive sensor had detected anything.

If there are explosive molecules in its groundwater, the plant draws them up into its leaves in about ten minutes, where they encounter the detector.

Researchers shine a laser onto the leaf, prompting the nanotubes in the leaf to release near-infrared fluorescent light to read the signal, which will be detected by a small infrared camera connected to a Raspberry Pi computer.

This setup can be used by the researchers to identify signals about 1m away from the plant.

So far, the researchers have also engineered spinach plants that can detect dopamine, which influences plant root growth.

Image: MIT engineers have transformed spinach plants into sensors that can detect explosives. Photo: courtesy of Christine Daniloff / MIT.