Studies have shown that up to half of the fruit sold in the EU contains residues of pesticides that have been linked to health issues in humans when exposed to large quantities.
Current methods for detecting these pesticides on small amounts or single items for consumption are restricted in practice by the high cost and cumbersome size of sensors.
Now, a new type of nanosensor has been developed that is inexpensive, reproducible and could potentially be used in situ at a store or other point of sale.
The technique makes use of flame-sprayed silver nanoparticles that are able to boost the readable signals of certain chemicals by more than a million times.
The sensing technique, known as surface-enhanced Raman scattering or SERS, increases the diagnostic signals of biomolecules on metal surfaces.
It has been used in a number of different fields, but high production costs and limited reproducibility have so far provided a bar for its use in food hygiene.
Flame spray delivered silver nanoparticles onto a glass surface
The new nanosensors, developed by a team from Karolinska Institutet in Sweden, used a flame spray to deliver small droplets of silver nanoparticles onto a glass surface.
Haipeng Li, the first author of the research, which was published in the journal Advanced Science, explained that this was able to quickly produce uniform SERS films across a large area – tackling one of the major issues of scalability.
The researchers then increased the sensitivity of individual silver nanoparticles by fine-tuning the distance between them.
In order to test their ability to detect chemicals, they added a thin layer of tracer dye to the SERS film and used a spectrometer to unlock their ‘molecular fingerprints’.
The study detailed how the nanosensors were able to uniformly detect the molecular signals.
They also tested the sensors’ performance again after two and a half months to demonstrate their potential shelf-life.
The researchers calibrated the sensors to detect minute amounts of a toxic pesticide known as parathion-ethyl, which is either banned outright or restricted in most markets.
A small amount of the substance was applied to part of an apple and a swab was later taken to look for residues.
The nanosensors were able to detect the presence of the insecticide when the swab had been immersed in a solution to dissolve the collected molecules.
The test was able to produce a positive result in just five minutes, without destroying the fruit.
Today’s news was brought to you by TD SYNNEX – the UK’s number one solutions distributor.
Read more of our latest Industry Updates stories
