Detection of staphylococcal enterotoxin C2 employing a piezoelectric crystal immunosensor

This paper reports the detection of Staphylococcal Enterotoxin C2 (SEC2) employing a reusable piezoelectric (PZ) immunosensor. Three different immobilization methods of SEC2 antibody on a gold electrode of the PZ were tested. Differences on stability and sensitivity were observed among the immobilization methods. The electrode coated with protein A gave the best result. Immobilized ratio of SEC2 antibody with protein A method was 82%. The immunosensor could be repeatedly used for six times. The protein A-coated crystal was stable for 12 weeks when stored at 4°C under the dry atmosphere. For repeated uses, the adsorbed antigen could be removed from the crystal by washing with 8 mol/l urea. When the antibody-immobilized crystal was immersed in 1.2 mol/l NaOH and then 1.2 mol/l HCl, all substances could be removed from the crystal surface, and the quartz crystal could be reused for many times.