It’s a story between TikTok, nanoparticles, the hard work of a laboratory and the most famous pesticide on the planet. A team from Concordia University has developed a system capable of detecting glyphosate from very low concentrations in liquids.
Glyphosate remains the most used pesticide in Quebec. It represented almost half of pesticide sales in the province in the latest available report for 2021. Present in different formulas, it is part of the recipe for Roundup, the popular herbicide first marketed by Monsanto. Bayer, which bought this company, had to set aside 16 billion US dollars to cover the risk created by more than 160,000 lawsuits.
Every scientific project first germinates in the brain of a researcher, and the spark comes from social networks. “Like most young people my age, I was watching TikTok and I saw a short video showing that they had found glyphosate in more than 20 different groats available in grocery stores,” says Adryanne Clermont-Paquette.
She understood that “it was clearly not a good thing to have in our food,” and that’s where the desire to be able to better detect it started.
A doctoral student in biology and lead author of the study published on this subject, she is part of the Nanosciences Research Center, which includes the Advanced Materials Laboratory led by Professor Rafik Naccache, supervisor of this research project. “We already had an area in environmental research, where we looked to detect harmful metals in water, such as mercury or lead. So, it’s something that was within our expertise,” explains this chemist and researcher in functional materials.
The mechanism
To detect glyphosate, the Concordia team uses nanoparticles called carbon dots. “The simplest way to explain is that if you take a hair, it’s already thin. You have to divide it by 50,000 to 60,000 times, and there we are talking about a nanoparticle,” says Mr. Naccache.
With a size of 10 nanometers or less, these carbon nanoparticles have very interesting optical properties, explain the two scientists. “When we excite them with a wave of light, they will generate a color emission that we see,” explains Professor Naccache.
“Our nanoparticles each have two color waves when we put them on a UV source: blue and red,” continues Mme Clermont-Paquette. By putting these microscopic particles in liquids that contain glyphosate, this light signal changes color.
The simplest way to explain is that if you take a hair, it is already thin. You have to divide it 50,000 to 60,000 times, and there we are talking about a nanoparticle.
The blue fluorescence remains constant, but the red changes in intensity due to interactions on the surface of the nanoparticles and the pesticide in question, describes the professor. It is this change that is measured and quantified. It is therefore a system of “self-reference”, with blue as a reference point, which remains the same. This allows you to know with confidence that the observed change is truly because of glyphosate and not because of other factors (like pH, for example).
It is a “specific system oriented towards glyphosate”, which makes it possible to ignore other variables, explains the doctoral student.
This technique makes it possible to detect the herbicide, from very small quantities to more appreciable concentrations. Moreover, the two researchers are not specialists in toxicity, they specify. Deciding at what concentration or exposure it is appropriate to detect is therefore not the goal of their research. It is rather to develop tools – these very small sensors – which can be used by others, by those who seek to document the presence of glyphosate to conclude whether it has a harmful effect or not.
The rest of things
This system has been tested in a laboratory for now, a controlled environment. “Now, we want an extension of our work with real samples taken in certain specific locations,” says Professor Rafik Naccache. Soil samples would pose other challenges, since it is a very complex material, with many other “interferences” that could act on the carbon dots.
The idea is also to create a system that is easy to use and not too expensive to produce. The detection of molecules in the environment generally requires very expensive equipment and technicians with extensive studies.
“We are trying to better understand this system, to increase its capacity or to apply it to other species of molecules which are involved in environmental pollution,” adds Adryanne Clermont-Paquette. She is therefore closely interested in pharmaceutical products consumed by humans that end up in water sources through the sewer network.
Remember that glyphosate was designated in 2015 as a “probable carcinogen” by the International Agency for Research on Cancer, an agency of the World Health Organization. Health Canada, however, maintains its approval of this product until 2032, justifying that it took into account the level of exposure of Canadians to the herbicide.
This content is produced in collaboration with Concordia University.