The nano-sensor detects pesticides on the fruit in minutes – ScienceDaily

Researchers at the Karolinska Institutet in Sweden have developed a small sensor to detect pesticides on fruit in just a few minutes. The technique described as proof of concept in an article in the magazine Advanced science, uses flame-scattered nanoparticles made of silver to increase the signal of chemicals. While still in the early stages, researchers hope that these nano-sensors can help detect food pesticides before consumption.

“Reports show that up to half of all fruit sold in the EU contains pesticide residues, which in greater quantities are linked to human health problems,” said Georgios Sotiriou, chief researcher at the Department of Microbiology, Tumors and Cell biology, Karolinska Institutet, and the corresponding author of the study. “However, current techniques for detecting pesticides on individual products before consumption are limited in practice by the high cost and cumbersome production of sensors. To overcome this, we have developed low-cost and reproducible nanosensors that could be used to monitor traces of fruit pesticides in the store, for example. “

The new nanosensors use a discovery from the 1970s known as surface-enhanced Raman scattering or SERS, a powerful sensor technique that can increase the diagnostic signals of biomolecules on metal surfaces by more than 1 million times. The technology has been used in several research areas, including chemical and environmental analysis, as well as to detect biomarkers for various diseases. However, high production costs and limited batch-to-batch reproducibility have so far hampered widespread use in food safety diagnostics.

Flame spraying technology

In the current study, researchers created the SERS nano-sensor using a flame spray – a well-established and cost-effective metal coating technique – to deliver small droplets of silver nanoparticles to a glass surface.

“Flame spray can be used to quickly produce uniform SERS films over large areas, removing one of the key barriers to scalability,” said Hypen Lee, a PhD student in Sotiriou’s laboratory and the study’s lead author.

The researchers then fine-tuned the distance between the individual silver nanoparticles to improve their sensitivity. To test their ability to detect substances, they apply a thin layer of trace dye to the sensors and use a spectrometer to detect their molecular fingerprints. The sensors reliably and evenly detect molecular signals, and their performance remains intact when retested after 2.5 months, underscoring their potential for shelf life and feasibility for large-scale production, the researchers said.

Pesticides found on apples

To test the practical application of the sensors, researchers calibrated them to detect low concentrations of parathion-ethyl, a toxic agricultural insecticide that is banned or restricted in most countries. A small amount of parathion-ethyl is placed on a piece of apple. The residue was later collected with a cotton swab dipped in a solution to dissolve the pesticide molecules. The solution was placed on the sensor, which confirmed the presence of pesticides.

“Our sensors can detect pesticide residues on apple surfaces in a short time of five minutes without destroying the fruit,” says Haipeng Lee. “While they need to be validated in larger studies, we offer a practical application with evidence of the concept of large-scale food safety testing before consumption.

Researchers then want to investigate whether nano-sensors can be applied in other areas, such as the detection of biomarkers for specific diseases at the site of care in resource-constrained settings.

The research is funded by the European Research Council (ERC), the Karolinska Institutet, the Swedish Foundation for Strategic Research (SSF) and the Swedish Research Council.

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Materials provided by Carolingian Institute. Note: Content can be edited for style and length.

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