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Electrochemical sensor selectively detects dangerous bacteria

| By Gerald Ondrey

Researchers at Goethe University Frankfurt ( and Kiel University (both Germany; have developed a new sensor for the detection of bacteria. It is based on a chip with a surface coating that ensures only very specific microorganisms, such as pathogens, adhere to the sensor.

The sensor makes use of the fact that microorganisms only ever attack certain body cells, which they recognize from the latter’s specific sugar molecule structure. This matrix, known as the glycocalyx, differs depending on the type of cell.

“In our study, we wanted to detect a specific strain of the gut bacterium Escherichia coli,” explains professor Andreas Terfort from the Institute of Inorganic and Analytical Chemistry at Goethe University Frankfurt. “We knew which cells the pathogen usually infects. We used this to coat our chip with an artificial glycocalyx that mimics the surface of these host cells. In this way, only bacteria from the targeted E. coli strain adhere to the sensor.”

The study, published in Applied Materials & Interfaces, documents how effective the sensing technique is. The researchers mixed pathogens from the targeted E. coli strain among harmless E. coli bacteria in various concentrations. “Our sensor was able to detect the harmful microorganisms even in very small quantities,” explains Terfort. “What’s more, the higher the concentration of the targeted bacteria, the stronger the emitted signals.”

The sensor is simpler to use than traditional methods, which are often time-consuming, require expensive equipment or can only be used by specialists. Moreover, they are often unable to distinguish between active bacteria and their decay products. A potential application is using the sensor in regions where there are no hospitals with sophisticated laboratory diagnostics, for example, or in bioreactors.

By using a customized surface to bait the targeted pathogens, they separate by themselves from a mixture of many different bacteria. This makes it easy to detect them electrochemically. Source: Sebastian Balser, Andreas Terfort Research Group, Goethe University Frankfurt