Purpose: The objective of this research was to develop a rapid and sensitive method for detection of C. jejuni in poultry products based on a quartz crystal microbalance (QCM) immunosensor using magnetic nanoparticles (MNPs) for separation and gold nanoparticles (GNPs) for detection.
Methods: The QCM sensor in a flow cell was prepared by immobilizing the mouse anti-C. jejuni monoclonal antibody (mAb1) on the sensor surface to specifically capture C. jejuni. Rabbit anti-C. jejuni polyclonal antibody (pAb1) was conjugated with MNPs to capture C. jejuni in food samples and separate them from food matrices. MNP-pAb1-C. jejuni complexes were injected into the flow cell to bind with the mAb1 immobilized on the QCM sensor surface. The goat anti-rabbit IgG antibody (Ab2) conjugated with GNPs were injected into the flow cell to bind with the pAb1 on MNPs. Finally, the resonant frequency changes were measured with the QCM sensor and correlated to the cell number of C. jejuni. The specificity of this immunosensor was confirmed with different strains of Campylobacter and other pathogens possibly associated with poultry products such as Salmonella Typhimurium and Salmonella Enteritidis. Broiler carcass wash and ground turkey samples were spiked with C. jejuni at different concentrations for use in the tests.
Results: The results showed that the QCM immunosensor could rapidly detect C. jejuni in poultry products with a detection limit of 10-30 CFU/ml and the total detection time of < 30 min. The characteristics of C. jejuni captured by the antibody immobilized on the surface of QCM sensor were visualized using atomic force microscopy (AFM).
Significance: This highly adaptive and flexible technique could provide the poultry industry a more rapid, sensitive, specific, and effective method for detection of major foodborne pathogens in poultry products.