Researchers at the University of Delaware have provided what is believed to be the first experimental evidence that plants can take up nanoparticles and accumulate them in their tissues.
The laboratory study, which involved pumpkin plants, indicates a possible pathway for nanoparticles to enter the food chain. The research also reveals a new experimental approach for studying nanoparticles and their potential impacts.
Yan Jin, professor of soil physics in the University of Delaware College of Agriculture and Natural Resources, and John Xiao, professor of physics and astronomy in the College of Arts and Sciences, led the study, working with colleagues Jung-youn Lee and Harsh Bais at the Delaware Biotechnology Institute, a premier research center at the University of Delaware.
The results were published in a cover article in the Journal of Environmental Monitoring and also were highlighted in Chemical Biology , a journal of the Royal Society of Chemistry.
Nanoparticles are bits of chemicals a thousand times smaller than a human cell. While nanoparticles occur naturally in the environment, they increasingly are being manufactured for use in electronics to cosmetics, fuel cells to medical procedures.
Yet the human and environmental health risks associated with these tiny engineered particles are not well known. Because chemical compounds can take on different properties at such a reduced size--lead in a pencil reportedly becomes stronger than steel, for example--there is concern that these invisible particles could easily be breathed in by humans and animals, with damaging or toxic effects.
"Plants serve as a foundation of the food chain," noted Jin, who was recently named a fellow of the Soil Society of America. "We demonstrated this possible route for nanoparticles in the environment--whether it poses potential harm to human health depends on many factors. This is a preliminary study, which we hope will spur additional interdisciplinary research by the scientific community."
The researchers chose pumpkins for the study, Jin said, because they take in a lot of water and are easy to grow.
The plants were grown hydroponically in an aqueous medium to which nanoparticles of iron oxide, or magnetite, a magnetic form of iron ore, were added.
After 20 days of growth, the plants were cut into pieces and dried in a vacuum dessicator. A magnetometer was then used to detect if any of the particles had been absorbed by the plant.
"Our study was a worst-case scenario in order to test the feasibility of our approach in being able to detect the particle," Xiao noted. "It really provides a new technique for doing this kind of research."
Xiao, who directs the Center for Spintronics and Biodetection at the University of Delaware, noted that the magnetometer used in his physics research is similar to magnetic resonance imaging (MRI), which uses a powerful magnetic field and radio-frequency pulses to produce images of internal structures in the human body.