A group of Massachusetts Institute of Technology engineers led by Michael Strano has changed ordinary spinach plants into biological bomb detectors with the help of nanotechnology. Their research is published in Nature Materials.
The MIT engineers applied nanoparticles to the underside of the leaves, enabling them to be taken up into the mesophyll layer where photosynthesis takes place. The installed nanotubes then function as sensors that are able to detect nitroaromatic compounds (commonly used in explosives like land mines) in the ground water taken up by the plants’ roots.
“Plants are very good analytical chemists,” Strano says. “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.”
When the researchers shine a laser on the nanotubes, they emit a fluorescent signal if the plant has picked up nitroaromatics. The process included hooking up a infrared camera to an inexpensive Raspberry Pi system and set it to email the user when the compounds are detected. This signal can be detected up to a metre away, but the researchers are working on making it work from further away.
The researchers also said that the process of explosive molecules making their way from the plant’s roots to the leaves can take about 10 minutes.
“Plants are very environmentally responsive,” Strano says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signalling pathways, there is a wealth of information to access.”
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