Gold, copper-infused device quickly detects bacteria responsible for food poisoning

Color-enhanced scanning electron micrograph showing Salmonella Typhimurium (red) invading cultured human cells. (Reference image Rocky Mountain Laboratories, NIAID, NIH, Wikimedia Commons.)

Using gold and copper, an Osaka Metropolitan University research team has created a handheld device for quick on-site detection of E. coli or salmonella, two bacteria known for causing human food poisoning.

In a paper published in the journal Analytical Chemistry, the Osaka researchers explain that they experimented with a biosensor that can simultaneously detect multiple disease-causing bacterial species within one hour.

“The palm-sized device for detection can be linked to a smartphone app to easily check bacterial contamination levels,” head scientist Hiroshi Shiigi said in a media statement.

Image of bacteria labeled with electrochemical markers, an electrochemical instrument to measure the data, and an image of the data displayed on a smartphone.
Image of bacteria labelled with electrochemical markers, an electrochemical instrument to measure the data, and the data displayed on a smartphone. (Graphic by Hiroshi Shiigi, Osaka Metropolitan University).

In detail, Shiigi’s group synthesized organic metallic nanohybrids of gold and copper that do not interfere with each other, so that electrochemical signals can be distinguished on the same screen-printed electrode chip of the biosensor.

These organic−inorganic hybrids are made up of conductive polymers and metal nanoparticles. The antibody for the specific target bacteria was then introduced into these nanohybrids to serve as electrochemical labels.

Results confirmed that the synthesized nanohybrids functioned as efficient electrochemical labels, enabling the simultaneous detection and quantification of multiple bacteria in less than 60 minutes.

“This technique enables rapid determination of the presence or absence of harmful bacteria prior to shipment of food and pharmaceutical products, thereby helping to quickly ensure safety at the manufacturing site,” Shiigi said.

Following this successful experiment, the team is now developing new organic metallic nanohybrids to simultaneously detect even more bacterial species.