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MSU’s Zhang Studying Nanoparticles as Potential Contaminant

Wei Zhang

Nanotechnology has been a topic of conversation in the scientific sphere for decades, but only recently has it forayed into agriculture. It involves the manipulation of materials at the atomic and molecular levels to perform a desired task.

In agriculture, nanotechnology has been developed in the form of nanocapsules for application of both pesticides and fertilizers. Additionally, nanosensors monitor soil and plant health. Although not widespread in use yet, agricultural nanotechnologies are on the cutting edge of innovation.

“This is really amazing technology that can be revolutionary for the agriculture industry,” said Wei Zhang, an assistant professor in the Department of Plant, Soil and Microbial Sciences at Michigan State University (MSU). “But it doesn’t come without questions or concerns. These are brand new technologies in some cases, and because they are becoming more pervasive, we need to learn more about them.”

Zhang is leading an MSU research team studying engineered nanoparticles (ENPs) as an emerging environmental contaminant. As more products employ nanotechnology — particularly in agriculture — the concentration of ENPs released into the environment will increase. Each of the team members assembled by Zhang is a highly respected researcher who brings knowledge in a different area: Sheng Yang He, an MSU University Distinguished Professor and plant pathologist; Hui Li, an associate professor and soil chemist; and Elliot Ryser, a professor and food safety expert.

The team is conducting tests in three phases on lettuce, tomato and spinach. “Fresh produce is the best option for our project because it’s minimally processed prior to being consumed,” Zhang said. “Many people want as little processing as possible for fruits and vegetables, but with that would come a higher likelihood of ENPs remaining in the product if it’s treated in the field with nanopesticides.”

The first step is to test the sorption of ENPs by the plants under various scenarios, such as nanopesticide application or irrigation with ENP-containing water. Understanding the interaction between the plant and ENPs will give researchers clues for developing effective remediation strategies.

Several projects investigating nanotechnology have delved into the uptake of ENPs through plant roots. Very few, however, have studied the role of stomata, the tiny pores in plant leaves that allow for respiration.

“The stomata can be quite large relative to ENPs,” Zhang said. “Stomata may be a few microns in diameter, whereas the nanoparticles may be just a couple hundred nanometers. Since 1,000 nanometers equals one micron, it’s not hard to see how the ENPs could enter through that pathway.”

In stage two, the team will evaluate how a series of different food processing washing conditions affect the ability of the plants to soak up ENPs. The outcomes may differ depending on the temperature or the type of sanitizer used.

Finally, after researchers pinpoint the optimum wash water composition, the produce will be cleaned in a processing line where the team will measure the removal of ENPs. This step will ideally allow the group to make food processing recommendations.

“We are in the stage of gathering information,” Zhang said. “Once we get a good idea as to the concentration of ENPs in the plants, we can begin to quantify the potential risks. But it’s important to understand the scale we’re talking about when we refer to nanotechnology. Just because something is present doesn’t mean it’s automatically harmful. That’s why we need to perform risk assessments. This technology has great potential, and it’s our duty to use it responsibly.”

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