Different biotinylation strategies for competitive immunoassay of estradiol

Study on biotinylation strategies for competitive immunoassay of estradiol (E_z) was carried out. Two types of competitive enzyme immunoassay (WIA) with Biotin-Avidin amplification system were established and optimized. The E₂-Biotin conjugate was used as a mere in one assay, and biotinylated antibody was used as a tracer in the other. In both of EIAs, horseradish peroxidase-labelled Avidin (Avidin-HRP) was used with a spectrometric determination of enzyme activity. The precision, sensitivity and specificity were measured and compared. The results showed that although both were satisfactory in specificity, the EL4 with hapten-Biotin showed to be superior to the EL4 with biotinylated antibody in sensitivity and precision. The limit of detection of serum E₂ was 8 and 50 pg/mL with E₂-Biotin and biotinylated antibody as tracer, respectively.