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Scientists have developed a new biosensor for use in a faster, more sensitive test for detecting the deadliest strain of Listeria.

There are numerous fast, highly effective tests already available for five of the six known species of Listeria. These tests use antibodies that signal the presence of the bacteria. However, there are few rapid, sensitive tests available for detecting L. monocytogenes. The new biosensor uses heat shock proteins instead of the antibodies used in other tests, and tests indicate that the sensor is faster and more sensitive at detecting the bacterium than antibody-based tests, with a microbe capture rate up to 83% greater than possible with the antibody-based tests.

The new biosensor will reduce the likelihood of false-positive results for L. monocytogenes in food and may lead to improved tests for detecting other types of pathogens.

Efficiently capturing a target analyte on a biosensor platform is a prerequisite for the reliable and specific detection of pathogenic microorganisms in a microfluidic chip. Antibodies have been widely used as ligands. However, because of their occasional unsatisfactory performance, researchers used heat shock protein 60 (Hsp60), a eukaryotic mitochondrial chaperon protein, as a receptor for Listeria adhesion protein LAP.

Hsp60, immobilized on the surface of streptavidin-coated silicon dioxide, specifically captured L. monocytogenes against a background of other Listeria species, Salmonella, Escherichia, Bacillus, Pseudomonas, Serratia, Hafnia, Enterobacter, Citrobacter and Lactobacillus. The capture efficiency of L. monocytogenes was 83 times greater than with another Listeria receptor, the monoclonal antibody mAb-C11E9. The capture rate was further increased on the Hsp60-coated biochip by 60% when a dielectrophoresis force was applied for 5 minutes.

Contact: Michael Ladisch, Department of Food Science, Purdue University, 745 Agriculture Mall Dr., West Lafayette, IN 47907. Phone: 765-494-7022. Fax: 765-494-7953. Email:
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Title Annotation:In brief...
Publication:Microbial Update International
Date:Feb 1, 2010
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