Engineers at the Massachusetts Institute of Technology (MIT) have repurposed spinach as a form of terrorism-prevention technology. ‘
The researchers have successfully embedded spinach leaves with carbon nanotubes, which turn the plants into detectors that can pick up potential explosives and wirelessly send information to handheld devices such as smartphones.
Engineering efforts that implement electronic systems into more organic environments have been minimal thus far, but this one marks a huge success. Undertaking this effort, the researchers have unlocked a new field that they call “plant nanobionics.”
“The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions,” Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the head of the nanobionics research efforts, said in a press release.
To make the project possible, the research team first had to determine which component of explosives is susceptible to detection by the plants, a complicated process.
The most efficient and applicable choice was a group of chemical compounds known as nitroaromatics which are often used in landmines.
Testing their novel technology, the MIT team found that, when a member of the nitroaromatic family is present in the groundwater naturally sampled by the plant, the embedded carbon nanotubes emit a fluorescent signal.
This signal triggers an infrared camera that can send an email alert about the potential explosive if the camera is connected to a computer.
Strano is interested in the potential applications of nanobionics to preventing pollution and predicting environmental disasters. Two years ago he and a former MIT postdoctoral researcher, Juan Pablo Giraldo, successfully demonstrated that scientists can use nanoparticles to allow plants’ photosynthetic abilities to detect nitric oxide, a pollutant that comes from combustion.
Strano’s research team has employed carbon nanotubes to detect hydrogen peroxide and sarin. When the molecule of interest binds to a polymer wrapped around a nanotube, the fluorescence of the tube is altered.
“Plants are very good analytical chemists,” Strano said. “They have an extensive root network in the soil, are constantly sampling groundwater and have a way to self-power the transport of that water up into the leaves.”
In the new spinach-based study, researchers utilize vascular infusion to embed the sensors for nitroaromatic compounds.
Vascular infusion involves applying a solution of nanoparticles to a leaf’s underside and placing the sensor into the mesophyll, the layer of the leaf where most photosynthetic actions take place.
Some of the carbon nanotubes emit a constant fluorescent signal, which makes it easy to detect an explosive signal. It takes approximately 10 minutes for plants to draw the chemical molecules into their leaves, then the sensor is triggered and the information is relayed.
In order to obtain the data, the MIT engineers use a laser to prompt the nanotubes in the leaf to emit near-infrared fluorescent signals that they can detect with a camera.
However, they can pick up the signal from only a meter away. This distance has been deemed inapplicable to many situations, and the researchers are working to increase the signal distance.
