Thursday, July 23, 2020

Using nanotechnology for more targeted, safer pesticide delivery

Nanoengineers at UC San Diego will develop more targeted ways to apply pesticides to food crops using plant virus nanocarriers, thanks to a $490,000 grant from the Department of Agriculture’s National Institute of Food and Agriculture. This could lead to a reduction in the amount of pesticide used, and therefore less chemical accumulation from pesticides in our food, drinking water and environment.

Engineers are using a plant virus as a nanocarrier
for more targeted pesticide delivery to protect crops
like tomatoes from root-eating nematodes. 
Pesticides are used extensively in food production to ensure crop health and yield. While these toxic chemicals can keep bugs, weeds, parasites, fungi and rodents from damaging crops, they also accumulate in the environment, in the crops themselves, and even in drinking water supplies, leading to adverse health effects for humans.

Nanoengineers led by Professor Nicole Steinmetz at the Jacobs School of Engineering plan to use a plant virus as a nanocarrier to more precisely deliver pesticide payloads when and where needed, resulting in less pesticide required, and less bioaccumulation. The team will study and use the tobacco mild green mosaic virus (TMGMV), which they’ve previously shown can carry cargo down to 30 centimeters below the soil surface, much deeper than traditional synthetic nanoparticles which travel 8 to 12 centimeters deep.

Their first target for these nanoparticles is a type of roundworm called a nematode, which eats plant roots, destroying the plant in the process. By being able to deliver the pesticide deeper into the plant’s root system, the researchers believe their plant virus nanoparticles will be more effective in stopping nematodes than synthetic pesticide delivery particles.

“In this project we focus on pesticides to target roundworms that infect the roots of crops, using our plant virus nanotechnology,” said Steinmetz.  “More specifically we will produce a library of nanoparticles derived from harmless plant viruses to answer how size, shape, and materials properties affect the nanocarriers interactions with soil and plants. Understanding these fundamental questions is expected to make an impact on next-generation pesticides, literally attacking the problem at its roots.”

Since plant viruses like TMGMV can be engineered to a custom size and certain physical properties, the researchers will study the effectiveness of plant virus nanocarriers of different sizes, shapes, and surface chemistries.  They’ll create a library of nanomaterials derived from TMGMV, detailing the nanocarriers’ pesticide delivery efficacy.

“We’ve seen that in medicine, changing the shape of a nanoparticle delivering a specific drug can lead to advantages such as enhanced diffusion and tissue penetration,” Steinmetz said. “We hypothesize that this is true for pesticide delivery as well, and will investigate the effect of nanocarrier size and shape on pesticide application effectiveness.”

The tobacco mild green mosaic virus is non-infectious to most plants, but the researchers will also create inactivation protocols to ensure it’s safe to use with any desired plant.  The virus is non-infectious in humans.

Steinmetz will collaborate with researchers Erin Rosskopf and Jason Hong at the USDA Agricultural Research Service, who will test candidate materials on nematode-infested crops.

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