Development Of Immunoassay For Perfluorooctanoic Acid Based On Heavy-chain Antibody

Perfluorooctanoic acid(PFOA) is a kind of perfluorinated compounds(PFCs) which has been used widely in the 20 th century because of its hydrophobicity and lipophobicity. Recently its impact on ecosystem and human health has aroused people's attention.Until now, most methods of PFOA analysis relied on the large instruments with high accuracy and low detection limit, e.g., liquid chromatography–mass spectrometry(LC-MS/MS). However, these methods were not suitable for in-field fast test due to some limitations, such as large machine, high cost and low throughput.In this study, we developed an immunological method for high-throughput detection of PFOA based on the specifically binding of the antigen and the antibody. At first, a PFOA-BSA complete antigen was synthesized using the carbodiimide method. The combining is succeed confirmed by SDS-PAGE and ion chromatograph analysis. The coupling ratio is 9 counted by TNBS method. Then a Llama variable domain of heavy chain antibody(VHH) phage display antibody library was used for screening specific antibody of this antigen and 7 positive clones were obtained after 4 round screening. The DNA region of these positive clones were ligated to the pET22b-Fc vector and the antibodies were expressed in a prokaryotic expression system. Finally, confirmed by the indirect competitive ELISA assay, a specific VHH antibody for PFOA was obtained, which might be used for fast analysis of PFOA in various media.