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Nanoparticles Enable Speedy E. coli Detection

E coli bacterium



COURTESY OF THE PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES
Escherichia coli is one of the most dangerous agents of food-borne disease and ingesting contaminated food or water can be deadly, especially for children or the elderly. Quick and accurate testing is crucial for avoiding potential infections, but in order to be effective many current tests require time-consuming amplification of samples. New findings indicate that specially treated nanoparticles of silica could allow researchers to detect a single E. coli bacterium in a ground beef sample, with no amplification required.

Weihong Tan and his colleagues at the University of Florida attached antibodies specific to the E. coli strain that causes food poisoning, O157:H7, to silica particles measuring just 60 nanometers across. The tiny particles also contained a few thousand fluorescent dye molecules. When the team mixed the particles into ground beef samples, the antibodies attached the silica to the bacteria. The signal given off by the dye allowed the scientists to detect a single bacterium in a sample in less than 20 minutes.

The new approach can be tailored to detect a variety of bacterial pathogens by changing the antibodies employed, according to a report published online this week by the Proceedings of the National Academy of Sciences. Indeed, the authors contend that the technique may ¿emerge as a revolutionary tool for ultrasensitive detection of disease markers and infectious agents.

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