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A group of MIT engineers has converted ordinary spinach plants into biological bomb detectors.

The team, led by Michael Strano, implanted customised carbon nanotubes into the leaves of living plants to turn them into a real-time natural monitoring system for explosive molecules.

When the plants suck water from the ground into the leaves, the carbon nanotubes can detect the presence of any nitroaromatics – chemical compounds often found in explosives such as landmines. When the researchers shine a laser on the nanotubes, they will discover a fluorescent signal if they pick up nitroaromatics. This signal can be detected by an infrared camera up to a meter away.

The research, published in  the Nature Materials journal, has yet to be tested in real curcumstances, but, according to newscientist.com, eventually it could be possible to sow seeds across a site suspected of containing landmines and use the plant detection system to locate them.

This isn’t the first time that plants have been tweaked using nanotechnology. Strano’s research group has used similar techniques to improve plants’ photosynthesis ability and to develop detectors for hydrogen peroxide, TNT, and the nerve gas sarin.

Plants are well suited to spotting different chemical compounds in ground water as they naturally develop extensive root networks, enabling them to sample a large area of soil. The latest research is “pushing the interaction of nanoparticles with biological systems,” says Matthew Baker from the University of Strathclyde.

He says one next possible step will be dispense with the infrared sensor. Other research has genetically modified plants so that they stop producing chlorophyll and change colour when exposed to certain substances in the ground, so the detectors need no extra technology.