Quantitation of estradiol by competitive light-initiated chemiluminescent assay using estriol as competitive antigen

Light-initiated chemiluminescent assays (LICA) are homogeneous assays that are sensitive, specific, and free of separation and washing steps and have high throughput and high precision.

In this research, we developed a competitive method by LICA to achieve accurate quantification of estradiol (E2) in human serum. E2 competed with estriol (E3) for binding to anti-human E2 antibodies. E3 was linked to biotin via bovine serum albumin as a linker. As this assay used competition between the labeled tracer and the analyte, an increase in E2 concentration will cause a signal decrease.

The expected detection range of E2 was 20-5000 pg/mL. The analytical and functional sensitivities were 7.16 and 13.7 pg/mL, respectively. The intra- and inter-assay coefficients of variation were both below 15%, and the recovery rate ranged from 97.5% to 106.8%. The interference rates ranged from -3.6% to 5.4% and met detection requirements for E2 in hyperbilirubinemia, hemolysis, and lipemia in clinical samples. In addition, the cross-reactivity rates between E2 and structural analogs and some reproductive hormones varied from 1.9% to 10.6% which showed that LICA is highly specific for E2. Moreover, our results showed high accordance with the IMMULITE 2000 (y = 0.6695x + 47.92, r²  = .843) and VIDAS systems (y = 1.099x - 821.5, r²  = .9392).

Our data show that the LICA, which is easy to automate, is a promising technique for quantification of E2 in human serum and could be used for clinical detection.