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Researchers at the Goethe University Frankfurt and the Christian Albrechts University in Kiel have developed a novel bacterial sensor. It is based on a chip with an innovative surface coating. It ensures that only very specific microorganisms stick to the sensor - for example certain pathogens. The greater their number, the stronger the electrical signal the chip produces. The sensor can not only detect dangerous bacteria with high sensitivity, but also determine their concentration.
Artificial Glycocalyx Aids Intact Bacteria Detection
The detection of harmful microorganisms is immensely important - not only in disease diagnosis, but also in the production of food. However, the procedures currently available are often time-consuming. It also requires expensive equipment or can only be carried out by specialists. In addition, they often cannot distinguish between active bacteria and their decay products.
The newly developed method, on the other hand, only detects intact bacteria. It takes advantage of the fact that microorganisms only ever attack certain body cells, which they recognize by a structure made up of special sugar molecules. This so-called glycocalyx varies from cell type to cell type. In a sense, it serves as an ID card for the body's cells.
That's exactly what the researchers did. “
In our study, we wanted to detect a specific strain of the intestinal bacterium Escherichia coli – E. coli for short,” said professor Andreas Terfort from the Institute for Inorganic and Analytical Chemistry at Goethe University. “
We knew which cells the pathogen normally infects. We used this to cover our chip with an artificial glycocalyx that mimics the surface of these host cells. Therefore, only bacteria from the desired E. coli strain stick to the sensor.”
E. coli has numerous small arms called pili. The bacterium uses them to recognize the glycocalyx of its host and clings to it. “
The bacteria bind to the sensor several times with their pili. This makes them particularly attached to it,” continued Terfort. The artificial glycocalyx is also chemically structured in such a way that microbes that do not have the right arms slide off it. This is similar to fried food from a well-greased pan. This ensures that only the pathogenic E. coli bacteria are retained.
The study documents how well this works. In it, the researchers mixed pathogens from the E. coli strain they were looking for in various concentrations with harmless E. coli bacteria. “
Our sensor was able to detect the harmful microorganisms even in very small quantities,” added Terfort. “
It also delivered stronger signals the higher the concentration of the bacteria we were looking for.”
Source: Goethe University Frankfurt am Main