An indirect competitive enzyme-linked immunosorbent assay for bisphenol-A based on the synthesis of a poly-L-lysine-hapten conjugate as a coating antigen

Bisphenol-A (BPA) is commonly suspected to act as an endocrine disruptor, thus it is important to detect BPA residues in water and food samples. An indirect competitive ELISA (ic-ELISA) method was developed in this study based on synthesis of a poly-L-lysine (PLL)-hapten conjugate as a coating antigen. The performance of the PLL-4,4-bis(4-hydroxyphenol) valeric acid (BVA) conjugate in the immunoassay was studied. The established method showed that the PLL-BVA coated format could improve the sensitivity of the ic-ELISA. The limit of detection was 0.5 ng mL(-1). IC50 value was 14.5 ng mL(-1), which was 9-fold lower than that ovalbumin (OVA)-BVA-coated methods. A good detection range from 1.3 ng mL(-1) to 292.2 ng mL(-1) was obtained. The recoveries from spiked samples were from 86.7% to 109.2%. The reliability of ELISA was validated by a high-performance liquid chromatography. These data demonstrated that the established ic-ELISA is a potential technique for detection of BPA.