Biosensor immunoassays for the detection of bisphenol A Original Research Article

Bisphenol A (BPA) is a xenoestrogen found in the environment, in consequence, for the biosensor detection of BPA we raised antibodies (polyclonal (PAbs) and monoclonal (MAbs)) against a structural analogue of BPA, 4,4 bis-(4-hydroxyphenyl) valeric acid (BVA). The kinetics of the MAb–BPA interaction were evaluated and the MAb providing the highest affinity was directly immobilized onto the sensor chip surface to evaluate a direct assay. Afterwards, the performance of the MAbs and the PAbs was compared in an inhibition assay using a BVA-coated chip. The highest sensitivity (limit of detection (LOD) of 0.4 μg L−1) was obtained with MAb 12 in the direct assay. However, the inhibition assay was the most robust and the PAbs showed the highest sensitivity (LOD of 0.5–1 μg L−1). The antibodies were specific for BVA and BPA as only minor cross-reactivities were found toward structurally related compounds or other endocrine disruptors. In the inhibition assay (with a run time of 6 min), water samples spiked with BPA at different levels (0.5–50 μg L−1) resulted in recoveries varying between 68% and 121%. The sensitivity of the inhibition assay could be improved 40 times (LOD of 0.03 μg L−1 with the Mab 12-based assay) using solid phase extraction (SPE).