An inexpensive test that can be used by everyone to detect “Escherichia coli”

Can we imagine an inexpensive test to detect the presence of toxic bacteria in a liquid at a glance? This is the challenge set by a transdisciplinary Canadian team bringing together specialists in biochemistry, biomedical engineering, chemical and mechanical engineering. The “proof of concept” that these scientists obtained, detailed in Advanced Materialsis a gel which turns red on contact with water contaminated by a toxic strain (specifically the O157:H7 strain) ofEscherichia coli (E. coli). The test is responsive in less than a day, can be used by everyone and costs around 50 euro cents. Research is now continuing to expand detection to other pathogenic bacterial sources.

To create such a tool, this team based its work on a previous result obtained at its McMaster University (Hamilton, Canada): the design of sensors from DNA, DNAzymes, catalysts capable of targeting and destroying molecules unwanted RNA, while preserving useful RNA strands.

The scientists were also inspired by work “using gels to detect heavy metal ions”, specifies one of the authors, associate professor Tohid Didar. In hindsight, the researchers also admit to having been pleasantly surprised by the effectiveness of one of their attempts: by adding bacteriophages to the DNAzyme hydrogel, they infected E. colireleasing a bacterial protein, which drastically reduced the detection time of the test. “This is the first time that bacteriophages have been used to amplify a signal to improve the detection performance of DNA-based sensors”, Extract Tohid Didar.

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