Detecting residual toxins on fruits with nanotechnology

Pesticides and herbicides are crucial for ensuring food security worldwide, but these substances can pose a safety risk to people who inadvertently consume them. Therefore, to protect human health, it is necessary to employ sensitive analytical methods to identify and even trace these harmful compounds.

Recently, researchers published a paper titled Cellulose Surface Nanoengineering for Visualizing Food Safety in the journal Nano Letters, detailing an imaging method for detecting low-level pesticide contamination. They showed that the method could be applied to fruits.

An analytical technique called surface-enhanced Raman spectroscopy (SERS) is gaining popularity as a non-destructive way to detect chemicals in modern agriculture. With SERS, nanoparticles are used to amplify the signals created by molecules when exposed to a Raman laser beam. These patterns created by the scattered light act as molecular signatures and can be used to identify small amounts of specific compounds.

Seeking to improve the sensitivity of SERS for pesticide detection, Dongdong Yi and his colleagues designed a metal-coated membrane that could be placed on top of agricultural crops. They also wanted to develop the material to be versatile enough to have a range of other applications.

The researchers started with a cellulose hydrogel film. The hydrogel film was stretched to create nano-sized wrinkles. They then immersed the film in a silver nitrate solution to fill the grooves with SERS-enhancing silver nanoparticles. The resulting membrane was highly flexible and virtually transparent in visible light, which is crucial for detecting the all-important SERS signal.

In testing the membrane for food safety applications, the researchers sprayed the pesticides trame and carbendazim, either alone or together, on apples and dried fruits and then rinsed them to simulate what a consumer would do to the fruit in their daily lives. When they applied their membrane to apples, SERS detected the pesticides on the apples. This detection was possible even when the chemicals were present in low concentrations. The team was also able to detect traces of pesticides at very low levels.

The researchers say these results suggest that washing alone can be sufficient to prevent pesticide ingestion, and that exfoliation is necessary to remove potential contamination from the skin. Beyond apples, they also used the SERS membrane system to detect pesticides on cucumbers, shrimp, chili powder, and rice.

https://www.mehrnews.com/news/6195305