Food defence requires the means to efficiently screen large volumes of food for microbial pathogens. Even rapid detection methods often require lengthy enrichment steps, making them impractical for this application. There is a great need for rapid, sensitive, specific, and inexpensive methods for extracting and concentrating microbial pathogens from food. In this study, an immunomagnetic separation (IMS) methodology was developed for
O157:H7, using three different types of magnetic nanoparticles (MNPs). The microbiological specificity of the IMS method was evaluated against
, and was improved by addition of NaCl during conjugation of antibodies onto MNPs. The microbiological sensitivity of the IMS method was greatest when a high concentration of antibodies (1.0 mg/ml) was present during conjugation. MNP concentrations of 1.0 mg/ml and 0.5 mg/ml provided optimal sensitivity and specificity. The entire IMS procedure requires only 35 minutes, and antibody-conjugated MNPs show no decline in performance up to 60 days after conjugation.
Keywords: foodborne pathogens, E. coli O157:H7, E. coli O55:H7, S higella boydii, immunomagnetic separation, IMS, magnetic nanoparticles, MNPs, iron oxide, polyaniline, core/shell nanoparticles, specificity, monoclonal antibody, food safety