Nano-Sensor Detects Pesticides on Fruit in Minutes

Researchers in Sweden at Karolinska Institutet have developed a tiny sensor for spotting fruit pesticides in just a few minutes. The method, referred as a proof-of-concept in a paper in the Advanced Science journal, utilizes flame-sprayed nanoparticles made from silver to increase chemical signals. The researchers hope these nano-sensors could assist in uncovering food pesticides before consumption while still at an early stage.

“Reports reveal that up to half of all fruits sold in the EU have pesticide residues that have been in larger quantities, linked to a human health conditions,” states Georgios Sotiriou, the study’s corresponding author and principal researcher at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet.

Nevertheless, present techniques for detecting pesticides on single products before consumption are restricted in practice by the high price and difficult production of its sensors. To overcome this, we developed low-cost and reproducible nano-sensors that could be used to monitor traces of fruit pesticides, for example, at the store.”

The new nano-sensors employ a 1970s discovery referred to as Surface-Enhanced Raman scattering, or SERS, a powerful sensing technique that can enhance the diagnostic signals of biomolecules on metal surfaces by more than 1 million times.

The technology has been utilized in numerous study areas, including the chemical and environmental evaluation and to detect biomarkers for numerous illnesses. However, high manufacturing prices and limited batch-to-batch reproducibility have until now hindered widespread application in food safety diagnostics.

Flame spray technology

In the present research, the researchers produced a SERS nano-sensor by utilizing flame spray, a well-established and cost-effective method for depositing metal coating to supply tiny droplets of silver nanoparticles onto a glass surface.

“The flame spray can be used across large areas to quickly produce uniform SERS films, getting rid of one of the key obstacles to scalability,” says Haipeng Li, a postdoctoral researcher in Sotiriou’s laboratory and the research’s first author.

The researchers then fine-tuned the distance between the individual silver nanoparticles to enhance their sensitivity. To test their substance-detecting ability, they applied a slim layer of tracer dye on top of the sensors and used a spectrometer to uncover their molecular fingerprints.

The sensors reliably and consistently spotted the molecular signals, and their performance remained intact when tested again after 2.5 months, which underscores their shelf life potential and feasibility for massive production, according to the researchers.

Detected pesticides on apples

To test the sensors’ practical application, the researchers calibrated them to spot low concentrations of parathion-ethyl, a toxic agricultural insecticide banned or restrained in most nations. A small amount of parathion-ethyl was positioned on the part of an apple. The residues were later collected with a cotton swab immersed in a solution to dissolve the pesticide molecules. The solution was dropped on the sensor, which confirmed the presence of pesticides.

“Our sensors can detect pesticide residues on apple surfaces in a short time of 5 minutes without destroying the fruit,” Haipeng Li states. “While they require to be validated in larger researches, we provide a proof-of-concept practical application for food safety testing at the range prior to consumption.”

Next, the researchers want to explore if the nano-sensors can be applied to other areas, such as finding biomarkers for particular illnesses at the point of treatment in resource-limited settings.

Read the original article on PHYS.

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