A novel insight in rapid allergen detection in food systems: From threshold dose to real-world concentration

Recently, food safety application of microfluidic device has drawn increasing attentions, whereas the research in this field is still limited due to the complexity of food systems. Most of immunosensor technology has endeavored to improve the sensitivity of the assay. However, the major challenges in food allergen detection are to simplify detection by creating a device with both rapid and broaden detection range from threshold to the real-world concentration. In this work, an ELISA-based colorimetric detection of allergen in food systems was achieved using microfluidic device and regular optical microscope. Casein, the major allergen in milk, was selected as a model analyte. The results indicated that the device was superior to the traditional method and substantially simplified the allergen detection, by demonstrating rapid detection, wide detection range from threshold to real-world concentration. The total detection time was reduced substantially from 45 min to 15 min without diminishing the detection limit. The linear detection range of antigen was also increased by 5-log difference. Moreover, this study also investigated the mechanism and kinetic study of TMB in-channel oxidation, and established a protocol to determine microfluidic channel size and TMB incubation time for allergen detection in food systems. Therefore, this work not only demonstrated the capability and superiority of microfluidic device for food safety application, but also provided a general optimization method for rapid allergen detection in food systems.