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How nanoparticle structures could help agriculture

Researchers are working to develop the “next generation” of insecticides that delivers active ingredients directly to pests
Justin Pahara, centre, and his colleagues at Agriculture Canada’s Lethbridge facilities are studying nanotechnology, or more specifically, nano-particles and their potential uses in agriculture.

In Hollywood, a movie about nanotechnology would probably feature an army of tiny robots threatening to destroy the world.

Then Ryan Reynolds and Sandra Bullock would show up to defeat the evil scientist who invented the robots.

In the real world, nanotechnology is much different.

It’s founded on chemistry. And the scientists aren’t evil.

“When people hear nanotechnology, they often think of these little robots,” said Justin Pahara, an Agriculture Canada researcher in Lethbridge.

“We’re able to build very small structures. By no means are we creating these little, intelligent robots.”

Pahara, who grew up on a farm near Lethbridge and earned a PhD at the University of Cambridge, is studying nanotechnology and how it can be applied in agriculture.

He’s one of hundreds of scientists around the globe who are looking at nano-particles and potential uses in agriculture.

“Nanotechnology has implications on every stage of farming, including seed germination, growth, harvest, processing, storage and transport of agricultural products,” says a 2022 paper from the Journal of Agriculture and Food Research.

 “Nano fertilizers, nano herbicides, nano fungicides, nano biosensors… are (some of) the novel applications of nanotechnology in the crop improvement area.”

Pahara is focusing on nano-insecticides to control crop pests.

“I thought the idea of next-generation crop treatments could be one of the biggest impact areas. I pitched that (concept) during my interview (for Agriculture Canada),” said Pahara, who joined Ag Canada a few years ago. “It seemed like a nice fit with potentially a huge global impact.”

With a PhD from Cambridge in synthetic biology and expertise in nanotechnology, Pahara could have taken a job in San Francisco, Europe or many other locations.

But he stayed close to home.

“Brain drain is a factor that is always talked about…. Canada trains a lot of high calibre people, but a lot leave,” he said in late May, from his office in Lethbridge.

“I wanted to stick around and help create some built-in-Canada stuff.”

Plus, there’s the added benefit of an easy commute. The Lethbridge Research Centre is an eight-minute drive from the Pahara family farm, where they grow alfalfa and other feed crops.

“You can call me a farm kid…. And I still live on our family farm.”

Pahara, who earned a Master’s degree in cell biology at the University of Alberta before going to Cambridge, said nano-technology is founded on chemistry.

A nano-particle is typically one to 100 nanometres in size. One nanometre is a billionth of a metre.

“It could (a nano-particle) involve a few thousand atoms,” Pahara said. “(But) you can think of it like chemistry. It looks like a chemistry lab. We don’t have any crazy equipment that can place things atom by atom.”

Some nano-particles are in-organic. They’re made from minerals like zinc oxide, silica and magnesium oxide.

To make a nano-particle using zinc oxide, a scientist could mix zinc chloride with an oxidizer chemical.

“You need to stir at the right temperature, for the right amount of time,” Pahara said.

“You get this slow growth of little nano-crystals.”

By changing the pressures, the temperatures and the chemicals added to the mixture, it’s possible to change the geometry and shape of the nano-crystals, he added.

“(Maybe) little nano-spheres…. You can make nano-rods…. People have made little nano-airplanes. Crystals that look like little airplanes.”

At Pahara’s lab in Lethbridge, the researchers don’t actually make nano-particles. They order them because it’s more efficient. They’re more interested in how the tiny particles can be used to control agricultural pests.

The idea is to deliver a nano-particle to a crop pest, say a lygus bug, by using a spray that contains the nano-crystals.

The nano-particle’s job is to transport an active ingredient that kills the lygus bug.

However, the active ingredient won’t be a traditional insecticide.

It will be a molecule, possibly a double-stranded RNA, that silences an important gene in the lygus bug and shuts down production of a target protein in the pest.

At this point, Pahara isn’t focusing on what’s inside the nano-particle and if it will kill a lygus bug or not.

He’s more concerned about delivery.

He wants to know exactly where the nano-particles go in the target pest. Which organ or tissue within the insect?

“By far, this is the most important (challenge),” he said. “Reliably getting (these) things into cells and knowing where they are going. If we don’t do that, we’re not going to be successful.”

A crude comparison could be a delivery company, like UPS.

If the UPS drivers can’t find the correct address, it doesn’t matter what packages are in the van.

Use of nano-particles is common in medicine. When Canadians received the Moderna or Pfizer vaccine for COVID-19, nano-particles delivered the vaccine.

“The overwhelming success of these two mRNA based vaccines… can be attributed to their unique nanocarrier,” says a 2021 paper published in Nano Today.

The key difference between medicine and agriculture, though, is the method of delivering the nano-particles.

“There is one huge advantage… with medicine, you can use a syringe. (In the) COVID vaccines, the RNA is carried in these little nano-vesicles…. And they’re able to get that RNA into your cells,” Pahara said.

“We can’t do that with insects or plants. You can’t have producers syringing all their plants in a field.”

In agriculture, the nano-particles will likely be delivered with a spray that goes on the crop and then into the crop pest.

A seed treatment is another possibility, but that is years down the road.

If Pahara and his team can sort out the technical issues, there’s still the matter of regulations. Health Canada and other regulators need to review the safety of a potential product.

It’s possible that nano-insecticides could be on the market in five to 10 years, says an Agriculture Canada document.

It might take longer, but Pahara remains optimistic and motivated.

“It’s very exciting because it’s so different from traditional (pest control),” he said.

“If we make a good contribution… it could change agriculture in a massive way. That’s what gets me excited.”

What is a nanometre?

Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometres. One nanometre is a billionth of a metre.

To put that in context:

  • There are 25,400,000 nanometres in an inch
  • A sheet of newspaper is about 100,000 nanometres thick
  • On a comparative scale, if a marble were a nanometre, the size of the Earth would be one metre

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