Food allergen detection with biosensor immunoassays.

An optical biosensor was used to develop both direct and sandwich immunoassays for the detection of proteins from milk, egg, hazelnut, peanut, shellfish, and sesame in food samples. Affinity-purified polyclonal antibodies raised against the proteins were immobilized on the biosensor chip. Food samples were injected and the proteins that bound to the antibodies on the surface were detected by a shift in the resonance angle. By adding a second antibody in a sandwich assay, matrix effects could be overcome and the sensitivity and selectivity enhanced. Detection of allergen levels down to 1-12.5 microg/g in food samples was demonstrated for the various assays. Good agreement of results was also obtained from parallel analysis with alternative immunoassays, including rocket immunoelectrophoresis, enzyme immunoassay, and immunoblotting. The present study demonstrates that the sensitivity of the described biosensor technique is comparable to the most sensitive enzymed-linked immunosorbent assays.