Multiplexed detection of foodborne pathogens on nanobiosensors

Investigator: Joseph Irudayaraj (Department of Agricultural and Biological Engineering)

Project Report 2012 - 2013

Consumption of foods contaminated with pathogenic bacteria is a major public health concern. Foods contain microorganisms, the overwhelming majority of which are nonpathogenic, some are responsible for food spoilage, and some cause serious illness leading to death or a variety of diseases in humans. The key challenge in food safety is to rapidly screen foods to determine the presence of pathogens so that appropriate intervention protocols can be pursued as needed. Nanobiosensors o?er advantages over traditional microbiological and standard-scale biosensors for pathogen detection because of their low cost, label-free detection options, and potential for massive parallelization. ARS-funded researchers in collaboration with Purdue University's Center for Food Safety Engineering in West Lafayette, Indiana, have made significant advances in developing and applying nanobiosensors that can simultaneously detect multiple types of foodborne pathogens. One of these nanobiosensors utilizes loop mediated isothermal amplification of DNA for on-chip parallel pathogen detection. Using these biochip sensors, scientists were able to rapidly and simultaneously detect L. monocytogenes, E. coli O157:H7, and Salmonella. Another nanobiosensor is based on an in situ fluorescent nanoparticle strategy. In this sensor, nanoparticle magnetic beads are coated with a capture antibody, which then forms a sandwich complex when the target pathogenic bacteria is present, resulting in the release of fluorophores. These fluorophores are easily detectable by common laboratory equipment. This nanoparticle magnetic bead method detected low numbers of E. coli O157:H7, S. typhimurium, and L. monocytogenes in less than 2 hours. These nanobiosensors could be used for fast, portable, and inexpensive on-site testing of foodborne pathogen contamination and could therefore be used to reduce the public health impact of foodborne pathogens.

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