A recent study has shown that the annual cost of foodborne illness in the Unites States is approximately $152 billion. This is a result of the estimated 76 million food-related illnesses which occur annually including approximately 5,000 deaths and 325,000 hospitalizations. Coast-to-coast and international distribution by megaprocessing plants puts potential outbreaks on a national and international scale. Therefore, monitoring of pathogen counts on processing surfaces is critical in maintaining low or zero counts in food products. There is a growing need for rapid and sensitive methods for the detection of pathogens and toxins in our food supply. Currently, most producers are using traditional testing methods which take days for results to be obtained. During this time, tons of product may have been distributed and consumed. Advances in nanotechnology have allowed more rapid and sensitive testing methods to be developed in the form of biosensors. These methods can be used to help identify potential dangers in food products prior to distribution. They would not only enable detection of pathogens and toxins, but allergens, antibiotics, hormones and genetically modified organisms. Not only will biosensors help protect against unintentional food contamination, but they could also help identify bioterrorist attacks. Analysis of an intentional bioterror attack on fluid milk using botulinum toxin concluded that the ability for rapid detection would have a significant impact on the reduction of fatalities.
The proposed biosensor will identify pathogens using their unique mRNA sequences. The structure of mRNA is very similar to DNA and is used as a blueprint to make proteins in the cell. The mRNA is rapidly degraded within the cell. Due to the stability of DNA and antibody binding sights on an organism, both DNA and immune testing could result in significant false positives by detecting non-viable pathogens inactivated by heat treatment or other means. The short half-life of mRNA suggests that if detected, the target organism was recently viable. This distinction is important for products such as fluid milk which have undergone heat treatment, yet still contain non-viable bacteria with intact DNA. The field of microfluidics has been rapidly growing. This is especially true in biosensor development. The use of microfluidic technology allows miniaturization of a test which adds to portability. Electrochemiluminescence (ECL) is a detection method which causes a specific molecule to glow by stimulating it with an electrical potential.
The proposed project aims to develop a microfluidic detection device. The device will be designed for rapid and portable testing. Both a core-shell nanoparticle and a polymer based reporter probe will be investigated for optimal sensitivity. The finished device will be used to test spiked food samples. The final biosensor will have two detection zones for multianalyte detection. One detection zone will target E. coli mRNA and the other will target Salmonella mRNA. The organisms will serve as indicators of contamination and will be independently quantified in a single assay.