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article imageSmartphone adapted to screen for food poisoning

By Tim Sandle     Apr 6, 2017 in Science
A smartphone has been successfully adapted to screen food samples for the pathogen Escherichia coli 0517. It is hoped the speed and portability of the application will enhance food safety.
This is on the basis that the easier it is for food manufacturers to test food samples then the more likely it is they will do so properly, leading to a reduction in the cases of E. coli food poisoning. In the U.S. alone there are some 73,000 cases per year.
The new application has been designed by Massachusetts Institute of Technology scientists. The test is based on the analysis of a liquid droplet, with the droplet capable of binding to specific bacterial proteins. This builds on earlier research into types of droplets called Janus emulsions. These droplets are formed from two equally sized hemispheres. Janus was the Roman god of beginnings, gates, transitions, time, duality, and doorways. The deity is usually depicted as having two faces, since he looks to the future and to the past.
One half is composed of a fluorocarbon and the other is formed from a hydrocarbon. Since the fluorocarbon is denser than the hydrocarbon when droplets sit on a surface, the fluorocarbon half remains at the bottom (a phenomenon called multivalency). These special optical properties allow the droplets to be used as sensors. From above the droplets are transparent but when viewed sideways they appear opaque. This property relates to the way that light passes through the droplet, and it is the path of light that can be adapted to make the sensor.
Building on this the scientists developed a surfactant molecule that contains mannose sugar to form the top half of the droplet surface. These molecules are capable of binding to a protein called lectin. Lectin is found on the surface of pathogenic strains of E. coli. The sensor works that when E. coli is present the droplets attach to the proteins. This causes the droplets to clump together causing light to scatter in many directions. The change in light scattering can be detected via a smartphone.
The new test is rapid, far quicker than conventional test methods for the pathogen that are based on culture-based techniques. It is also less expensive than rapid methods based on DNA testing. The new method is also simple and can be operated by people tasked with preparing food within a factory.
Explaining a clear advantage of the technology, one of the lead scientists, Professor Timothy Swager, states: “What we have here is something that can be massively cheaper, with low entry costs.” The sensor has been tested out with multiple samples of the infective bacterium and the results are sufficiently successful for the sensor to be considered for commercialization.
The research into the technology has been published in the journal Central Science. The research paper is headed “Janus Emulsions for the Detection of Bacteria.”
In related news, concerns about people getting ill from E. coli contamination have triggered a national food recall warning about a brand of flour in Canada. This has been initiated by the Canadian Food Inspection Agency and it relates to Robin Hood Original All Purpose Flour.
More about Food poisoning, Smartphone, Scanning, Pathogens
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