Tag Archives: glyphosate

A nanozyme that is organic, non-toxic, environmentally friendly, cost effective, and can detect the presence of glyphosate

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An October 16, 2023 University of Illinois news release (also on EurekAlert), describes research into developing a tool to detect the presence of the agricultural herbicide, glyphosate, Note: Links have been removed,

Nanozymes are synthetic materials that mimic the properties of natural enzymes for applications in biomedicine and chemical engineering. They are generally considered too toxic and expensive for use in agriculture and food science. Now, researchers from the University of Illinois Urbana-Champaign have developed a nanozyme that is organic, non-toxic, environmentally friendly, and cost effective. In a newly published paper, they describe its features and its capacity to detect the presence of glyphosate, a common agricultural herbicide. Their goal is to eventually create a user-friendly test kit for consumers and agricultural producers.

“The word nanozyme is derived from nanomaterial and enzyme. Nanozymes were first developed about 15 years ago, when researchers found that iron oxide nanoparticles may perform catalytic activity similar to natural enzymes (peroxidase),” explained Dong Hoon Lee, a doctoral student in the Department of Agricultural and Biological Engineering (ABE), part of the College of Agricultural, Consumer and Environmental Sciences (ACES) and The Grainger College of Engineering at U. of I.

These nanozymes mimic the activity of peroxidase, an enzyme that catalyzes the oxidation of a substrate by using hydrogen peroxide as an oxidizing agent. They provide higher stability and lower cost than natural peroxidase, and they are widely used in biomedical research, including biosensors for detection of target molecules in disease diagnostics.

“Traditional nanozymes are created from inorganic, metal-based materials, making them too toxic and expensive to be directly applied on food and agriculture,” Lee said.

“Our research group is pioneering the development of fully organic compound-based nanozymes (OC nanozymes) which exhibit peroxidase-like activities. The OC nanozyme follows the catalytic activity of the natural enzyme but is predominantly based on agriculture-friendly organic compounds, such as urea acting as a chelating-like agent and polyvinyl alcohol as a particle stabilizer.”

The researchers also implemented a colorimetric sensing system integrated with the OC nanozyme for target molecule detection. Colorimetric assays, an optical sensing method, use color intensity to provide an estimated concentration of the presence of specific molecules in a substance, such that darker or lighter color indicates lower or higher quantity of target molecules. The organic-compound nanozyme performed on par with nanozymes typically used in biosensing applications within their kinetic profile with molecule detection performance.

“Traditional nanozymes come with a host of issues: toxicity, lengthy degradation, and a complex production process. In contrast, our nanozyme is quicker to produce, cost-effective, non-toxic, and environmentally friendly,” said Mohammed Kamruzzaman, assistant professor in ABE and co-author on the study.

Lee and Kamruzzaman applied the OC nanozyme-based, colorimetric sensing platform to detect the presence of glyphosate, a widely used herbicide in the agricultural industry. They performed colorimetric assays in solutions containing varying concentrations of glyphosate, finding the organic nanozyme was able to successfully detect glyphosate with adequate accuracy.

“There is an increasing demand for testing pesticide or herbicide presence in agricultural products to protect human and crop health. We want to develop an OC nanozyme-based, point-of-use testing platform for farmers or consumers that they can apply in the field or at home,” Kamruzzaman stated. “People would obtain a test kit with a substance to mix with their sample, then take a picture and use an app on their phone to identify the color intensity and interpret if there is any glyphosate present. The ultimate goal is to make the test portable and applicable anywhere.”

The researchers are also working on developing additional nanozymes, envisioning these environmental-friendly materials hold great potential for a wide range of applications.

Here’s a link to and a citation for the paper,

Organic compound-based nanozymes for agricultural herbicide detection by Dong Hoon Lee and Mohammed Kamruzzaman. Nanoscale, 2023,15, 12954-12960 First published July 28, 2023

This paper is open access once you have created your free account.

Using carbon dots (organic nanosensors) to detect pesticides

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Before getting to the latest about carbon dots, there’s something to be clarified (and it was news to me), a carbon dot is not a quantum dot. So says this 2020 paper, “Advances in carbon dots: from the perspective of traditional quantum dots” by Yanhong Liu, Hui Huang, Weijing Cao, Baodong Mao, Yang Liu, and Zhenhui Kang. Mater. Chem. Front., 2020,4, 1586-1613 First published March 17, 2020.

Abstract

Quantum dots (QDs) have been the core concept of nanoscience and nanotechnology since their inception, and play a dominant role in the development of the nano-field. Carbon dots (CDots), defined by a feature size of <10 nm, have become a rising star in the crossover field of carbon materials and traditional QDs (TQDs). CDots possess many unique structural, physicochemical and photochemical properties that render them a promising platform for biology, devices, catalysis and other applications. …

This story is about carbon dots but you can find out more about quantum dots in my October 6, 2023 posting concerning the 2023 Nobel prizes; scroll down to the ‘Chemistry’ subhead.

An August 30, 2023 news item on phys.org describes work from Concordia University (Montréal, Canada) on carbon dots,

Researchers at Concordia have developed a new system using tiny nanosensors called carbon dots to detect the presence of the widely used chemical glyphosate. Their research, titled “Ratiometric Sensing of Glyphosate in Water Using Dual Fluorescent Carbon Dots,” is published in Sensors.

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An August 30, 2023 Concordia University news release (also on EurekAlert) by Patrick Lejtenyi, which originated the news item, explains the importance of the work and provides more technical details, Note: Links have been removed,

Glyphosate is a pesticide found in more than 750 agricultural, forestry, urban and home products, including Monsanto’s popular weed-killer Roundup. It is also controversial: studies have linked its overuse to environmental pollution and cancer in humans. Its sale is banned or restricted in dozens of countries and jurisdictions, including Canada.

The researchers’ system relies on the carbon dots’ chemical interaction with glyphosate to detect its presence. Carbon dots are exceedingly small fluorescent particles, usually no more than 10 or 15 nanometres in size (a human hair is between 80,000 and 100,000 nanometres). But when they are added to water solutions, these nanomaterials emit blue and red fluorescence.

The researchers employed an analysis technique called a ratiometric self-referencing assay to determine glyphosate levels in a solution. The red fluorescence emitted by the carbon dots when exposed to varying concentrations of the chemical and different pH levels is compared with a control in which no glyphosate is present. In all the tests, the blue fluorescence remained unchanged, giving the researchers a common reference point across the different tests.

They observed that higher levels of glyphosate quenched the red fluorescence, which they accredited to the interaction of the pesticide with the carbon dots’ surface.

“Our system differs from others because we are measuring the area between two peaks—two fluorescent signatures—on the visible spectrum,” says Adryanne Clermont-Paquette, a PhD candidate in biology and the paper’s lead author. “This is the integrated area between the two curves. Ratiometric measurement allows us to ignore variables such as temperature, pH levels or other environmental factors. That allows us to just only look at the levels of glyphosate and carbon dots that are in the system.”

“By understanding the chemistry at the surface of these very small dots and by knowing their optical properties, we can use them to our advantage for many different applications,” says Rafik Naccache, an associate professor of chemistry and biochemistry and the paper’s supervising author.

Research assistants Diego-Andrés Mendoza and Amir Sadeghi, along with associate professor of biology Alisa Piekny, are co-authors.

Starting small

Naccache says the technique is designed to detect minute amounts of the pesticide. The technique they developed is sensitive enough to be able to detect the presence of pesticide at levels as low as 0.03 parts per million.

“The challenge is always in the other direction, to see how low we can go in terms of sensitivity and selectivity,” he says.

There remains much work to be done before this technology can be used widely. But as Clermont-Paquette notes, this paper represents an important beginning.

“Understanding the interaction between glyphosate and carbon dots is a first step. If we are to move this along further, and develop it into a real-life application, we have to start with the fundamentals.”

The researchers are supported by funding from the Natural Sciences and Engineering Research Council of Canada.

Here’s a link to and a citation for the paper,

Ratiometric Sensing of Glyphosate in Water Using Dual Fluorescent Carbon Dots
by Adryanne Clermont-Paquette, Diego-Andrés Mendoza, Amir Sadeghi, Alisa Piekny, and Rafik Naccache. Sensors 2023, 23(11), 5200; DOI: https://doi.org/10.3390/s23115200 Published: 30 May 2023

This paper is open access.