Nano-sensor detects pesticides on fruit in minutes

Researchers at Karolinska Institute in Sweden have developed a tiny sensor for detecting pesticides on fruit in just a few minutes. The technique, described as a proof-of-concept in a paper in the journal Advanced Science, uses flame-sprayed nanoparticles made from silver to increase the signal of chemicals. While still at an early stage, the researchers hope these nano-sensors could help uncover food pesticides before consumption.

The new nano-sensors employ a 1970s discovery known as surface-enhanced Raman scattering, or SERS, a powerful sensing 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 fields, 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 hindered widespread application in food safety diagnostics.

Now, lets look at what The flame spray technology is:

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

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 thin layer of tracer dye on top of the sensors and used a spectrometer to uncover their molecular fingerprints. The sensors reliably and uniformly detected the molecular signals and their performance remained intact when tested again.

To test the sensors' practical application, the 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 was placed on part of an apple. The residues were later collected with a cotton swab that was immersed in a solution to dissolve the pesticide molecules. The solution was dropped on the sensor, which confirmed the presence of pesticides. So this nano sensor technology has proven to be highly efficacious in detecting the pesticides lingering on surfaces of fruits and vegetables.