Development of an immunosensor for quantifying zebrafish vitellogenin based on the Octet system.

Vitellogenin (Vtg) is a sensitive biomarker for environmental estrogens. In this study, an immunosensor for quantifying zebrafish Vtg was developed using the Octet system. First, Protein A sensors were immobilized with purified anti-lipovitellin (Lv) antibody that demonstrated specificity to Vtg. Then, antibody-coated biosensors were immersed into zebrafish Lv standards and diluted samples. The Octet system measured and recorded kinetic parameters between antigens and captured antibody within 5 min. Sample Vtg concentrations were automatically calculated by interpolating relative binding rates observed with each sample and the immobilized anti-Lv antibody into the developed standard curve. The sensor arrays exhibited a wide linear range from 78 to 5000 ng/mL, and the inter-assay coefficient of variation was 0.66-1.97%. Furthermore, the performance of the immunosensor in detecting Vtg was evaluated by quantifying Vtg induction in juvenile zebrafish exposed to 17β-estradiol (E2). Compared with conventional immunoassay techniques, the Vtg immunosensor developed based on the Octet system was much simpler and less time-consuming, allowing rapid Vtg quantification within 15 min. Moreover, Protein A sensors could be reused many times to ensure that the assays have high reproducibility. Therefore, we suggest that immunosensors based on the Octet system are an easily operated detection method for ecotoxicological research.