A plant-based sensor to monitor arsenic levels in the soil

Nanoscale devices integrated into the leaves of living plants can detect the toxic heavy metal in real-time.

MIT scientists have developed a plant nanobionic optical sensor to detect and monitor toxic heavy metal arsenic in real-time. The sensor can benefit from old techniques of measuring arsenic in the environment.

Arsenic is a natural component of the earth’s crust and is widely distributed throughout the air, water, and land environment. It is highly toxic in its inorganic form. According to scientists, this newly engineered sensor will play a vital role in environmental monitoring and agricultural applications to safeguard food safety.

Tedrick Thomas Salim Lew, a recent graduate student of MIT, said, “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. We envision that this innovation will eventually see wide use in the agriculture industry and beyond. I am grateful to SMART DiSTAP and the Temasek Life Sciences Laboratory (TLL), both of which were instrumental in idea generation and scientific discussion as well as research funding for this work.”

How does the sensor work?

Once detecting arsenic, the novel optical nanosensors exhibit changes in their fluorescence intensity and provide a nondestructive way to monitor the arsenic’s internal dynamics taken up by plants from the soil.

Embedded in plant tissues, the optical nanosensors enable converting 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.

Scientists tested the optical nanosensor on rice and spinach plants and a species of fern, Pteris cretica. Pteris cretica can absorb and tolerate high levels of arsenic with no detrimental effect.

The optical nanosensors were found as effective in detecting arsenic in all tests. It can detect deficient concentrations of arsenic, as low as 0.2 parts per billion.

Scientists noted, “The novel nanosensors can also be integrated into other species of plants. 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 (e.g., to monitor arsenic taken up by edible crops for food safety) and general environmental monitoring.”

Co-author, DiSTAP co-lead principal investigator, and MIT Professor Michael Strano add, “This is a hugely exciting development, as, for the first time, we have developed a nanobionic sensor that can detect arsenic— a serious environmental contaminant and potential public health threat. With its myriad advantages over older methods of arsenic detection, 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 to produce further crops that resist uptake of toxic elements. Inspired by TLL’s recent efforts to create rice crops that take up less arsenic, this work is a parallel effort to further support SMART DiSTAP’s efforts in food security research, constantly innovating and developing new technological capabilities to improve Singapore’s food quality and safety.”

The research is carried out by the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) and Singapore-MIT Alliance for Research and Technology (SMART) and supported by the National Research Foundation (NRF) Singapore under its Campus for Research Excellence And Technological Enterprise (CREATE) program.

Journal Reference:
  1. Tedrick Thomas Salim Lew et al. Plant Nanobionic Sensors for Arsenic Detection. DOI: 10.1002/adma.202005683

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