Real time biosensor analysis of staphylococcal enterotoxin A in food.

Currently there is no 'real-time' detection system to identify food borne toxins. In order to develop such a system, we have used a evanescent wave biosensor for real time detection of staphylococcal enterotoxin A (SEA) in foods. The approach used here is sandwich biosensor, a method utilizing two antibodies. The toxin binds initially to a capturing antibody which is bound covalently on the surface of the biosensor detector. The second antibody binds to the captured toxin. We were able to measure SEA in foods with little or no background interference, demonstrating that biosensor-based measurement of SEA was possible not only with purified SEA but also in complex food matrices such as hot dogs, potato salad, milk and mushrooms. Autoclaved samples of SEA did not evoke a positive response. With both purified SEA and SEA-spiked foods, the assay sensitivity is 10-100 ng/g depending on the material tested and the assay is rapid ( <4 min) when a single antibody is used.