Nanosensors turn plants into self-powered arsenic detectors
Arsenic is a contaminant in many common agricultural products such as rice, vegetables, and tea leaves, and is considered a serious threat to both humans and ecosystems. The new sensor, say the researchers, provides significant advantages over conventional methods used to measure arsenic in the environment and will be important for both environmental monitoring and agricultural applications to safeguard food safety.
The scientists say they exploited the natural ability of wild-type plants to pre-concentrate and extract arsenic from the below-ground environment to engineer plant nanobionic sensors for real-time arsenic detection. Embedded in plant tissues, with no detrimental effects on the plant, the near-infrared fluorescent nanosensors exhibit changes in their fluorescence intensity upon detecting arsenic, provide a nondestructive way to monitor the internal dynamics of arsenic taken up by plants from the soil.
This integration of optical nanosensors within living plants, say the researchers, enables the conversion of plants into self-powered detectors of arsenic from their natural environment, marking a significant upgrade from the time- and equipment-intensive arsenic sampling methods of current conventional methods.
“Our plant-based nanosensor is notable not only for being the first of its kind, but also for the significant advantages it confers over conventional methods of measuring arsenic levels in the below-ground environment, requiring less time, equipment, and manpower,” says Tedrick Thomas Salim Lew, a recent graduate student of MIT and lead author of a paper on the research. “We envision that this innovation will eventually see wide use in the agriculture industry and beyond.”
The researchers demonstrated arsenite detection using three different plant species as nanobionic sensors: in addition to detecting arsenic in rice and spinach, they also used a species of fern (Pteris cretica), which can hyperaccumulate arsenic. This fern species can absorb and tolerate high levels of arsenic with no detrimental effect – engineering an ultrasensitive plant-based arsenic detector capable of detecting very low concentrations of arsenic, as low as 0.2 parts per billion. In contrast, the regulatory limit for arsenic detectors is 10 parts per billion.
Notably, the novel nanosensors can also be integrated into other species of plants. The researchers say this is the first successful demonstration of living plant-based sensors for arsenic and represents a groundbreaking advancement that could prove highly useful in both agricultural research and general environmental monitoring.
Previously, conventional methods of measuring arsenic levels included regular field sampling, plant tissue digestion, extraction, and analysis using mass spectrometry – methods that are time-consuming, require extensive sample treatment, and often involve the use of bulky and expensive instrumentation. The new approach couples nanoparticle sensors with plants’ natural ability to efficiently extract analytes via the roots and transport them.
This, say the researchers, allows for the detection of arsenic uptake in living plants in real time, with portable, inexpensive electronics such as a portable Raspberry Pi platform equipped with a charge-coupled device camera akin to a smartphone camera.
“With its myriad advantages over older methods of arsenic detection,” says paper co-author, DiSTAP co-lead principal investigator, and MIT Professor Michael Strano, “this novel sensor could be a game-changer, as it is not only more time-efficient, but also more accurate and easier to deploy than older methods. It will also help plant scientists in organizations such as TLL [Temasek Life Sciences Laboratory] to further produce crops that resist uptake of toxic elements.”
For more, see “Plant Nanobionic Sensors for Arsenic Detection.”
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