They’ve trained rats, bees, and even dolphins to sniff out landmines, but scientists are now turning their attention to an even more unlikely bomb-detecting ally: spinach.
Already famous for its health benefits, spinach could soon add even more years onto people’s lives by helping to uncover hidden explosives and avoid casualties. This is thanks to the work of researchers from the Massachusetts Institute of Technology (MIT), who used a technique called vascular infusion to introduce carbon nanotubes into the leaves of the plant.
These nanotubes were specifically designed to interact with chemical compounds called nitroaromatics, which are commonly used in explosive devices. In their experiments – which are described in the journal Nature Materials – the researchers focused on a nitoaromatic called picric acid.
As the acid is absorbed from the groundwater by the plant’s roots, it is transported to the mesophyll layer on the underside of the leaf, where most photosynthesis takes place, and where the nanotubes are waiting to detect it.
When the researchers shine a laser on these nanotubes, they give off a fluorescent signal in order to indicate that nitroaromatics have been detected. This signal can be seen using an infrared camera from up to a meter away, although the team are working to find a way of picking it up from greater distances.
The integration of electronic systems into plants has been termed “plant nanobionics”, and study co-author Michael Strano has described his team’s approach as “a novel demonstration of how we have overcome the plant/human communication barrier.”
Overall, it takes around 10 minutes for nitroaromatics to reach the plant’s leaves after being drawn up from the groundwater, and while some animals may be able to sniff out explosive chemicals more quickly, Strano says that “plants are very good chemical analysts.”
“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,” he said.
Not to mention the fact that if they do happen to get blown up in the process, there’s a lot less pain, suffering, and mess.