Piezoelectric crystal immunosensor for the detection of staphylococcal enterotoxin B

The work of fabricating a piezoelectric (PZ) immunosensor for the detection of staphylococcal enterotoxin B (SEB) is presented in this paper. Three different immobilization methods using anti-SEB antibody onto a gold electrode of the PZ have been conducted. The electrode coated with polyethyleneimine (PEI) has shown the best result. The fabricated PZ sensor can be used for SEB determination in the range of 2.5-60 microg/ml with a correlation coefficient of 0.997. Milk samples spiked with various concentrations of SEB gave an average of 111% recovery of the toxin. The SEB assay is specific. For example the presence of staphylococcal enterotoxin A (SEA) at 40 microg/ml gave 6.44% of the signal while staphylococcal enterotoxin D (SED) appeared to give no detectable signal. After regeneration with 1.2 M NaOH, the coated crystal could be reused three times with retention of 66% of the initial signal. The crystal has also been found to be stable for 3 days when stored at 4 degrees C in a dry atmosphere without appreciable loss of activity.