A new method for broadening the detection range of immunoassay and its application in β-hCG quantitative detection

Early pregnancy prediction requires very high beta-hCG detection sensitivity, while embryonic development monitoring and trophoblastic disease detection require a wider detection range. In this study, based on light-initiated chemiluminescence assay (LICA), one high-affinity mAb and one low-affinity mAb were selected and coated on chemibeads with a larger coating area in different ratios to immobilize the antibodies. The two immobilized mAbs were mixed with different concentrations to detect beta-hCG. When the high-affinity mAb-coated chemibeads and low-affinity mAb-coated chemibeads were used at working concentrations of 0.100 mg mL(-1) and 0.014 mg mL(-1), respectively, the sensitivity and detection range were maximized. The assay was precise for measuring beta-hCG with repeatability and intermediate precision of <5% CV. The assay has a high sensitivity with a limit of quantification (LoQ) of 0.49 IU L-1, which is lower than that of most beta-hCG detection kits. Over the range of 1 IU L-1 to 16 000 IU L-1, the assay had a proper linearity (r = 0.9995). No false negative results due to the hook effect were observed at beta-hCG concentrations up to 225 000 IU L-1. The assay showed a good correlation with the Abbott assay (r = 0.9910). LICA combined with immobilized mAbs with different affinities ensures the sensitivity of beta-hCG detection and broadens the detection range.

Automated summary

Early pregnancy prediction requires high sensitivity in beta-hCG detection, while embryonic development monitoring and trophoblastic disease detection require a wider detection range. In this study, a light-initiated chemiluminescence assay (LICA) was used with immobilized monoclonal antibodies (mAbs) of different affinities to detect beta-hCG. The assay showed high sensitivity, good linearity, and correlation with a standard assay, making it a reliable method for beta-hCG detection.