One-step all-in-one dry reagent immunoassays with fluorescent europium chelate label and time-resolved fluorometry

Abstract

The availability of an intrinsically fluorescent, inert, and stable Eu chelate label made it feasible to design one-step all-in-one immunoassays with time-resolved fluorometry for detection. Both competitive and noncompetitive immunoassays are performed in microtitration wells containing all assay-specific components in a stable dry form. Only the sample and one assay buffer common for all analytes need to be added. Model assays for human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), and progesterone all reached equilibrium in 15 min or less without compromising the performance characteristics of the measurements, all of which perform at least equivalent to state-of-the-art assays. The detection limits for hCG, AFP, and progesterone were 0.3 IU/L, 0.1 microgram/L, and 0.5 nmol/L, respectively. The assay ranges for hCG and AFP were linear to 5000 IU/L and 1200 micrograms/L, respectively. The immunoassay format can be readily implemented in a fully automated random-access immunoassay system with optimal performance characteristics and no handling of analyte-specific assay components.

Second‐trimester maternal serum free‐β‐human chorionic gonadotropin and α‐fetoprotein levels in normal twin and singleton pregnancies: a report of local Chinese population

“…All the serum samples were separated within 24 h after collection and stored under −20 • C. All samples were assayed in the laboratory of the Women's Hospital, School of Medicine, Zhejiang University, China. Levels of free β-hCG and AFP were measured by using a commercial time-resolved fluoroimmunoassay (AutoDELFIA1235, PerkinElmer Life and Analytical Sciences, USA) (Lovgren et al, 1996).…”

Contingent triple‐screening for Down syndrome in the second trimester: a feasibility study in Mainland Chinese population

“…Part of each serum sample was used for double-screening and the rest was stored at −80 • C until testing. Levels of freebeta human chorionic gonadotropin (free β-hCG) and AFP were measured by a commercial time-resolved fluoroimmunoassay (AutoDELFIA1235, PerkinElmer Life and Analytical Sciences, USA) (Lovgren et al, 1996). Risk calculation was performed using the 2T-RISK software (PerkinElmer Life and Analytical Sciences), and cutoff was set at 1/270.…”

Improved early risk stratification and diagnosis of myocardial infarction, using a novel troponin I assay concept

“…The investigational cTnI assay has been designed to be minimally affected by the presence of the factor causing negative interference in many cTnI immunoassays. In brief, the assay is a one-step immunofluorometric sandwich assay based on the all-in-one dry chemistry concept [9]. It uses two biotinylated monoclonal cTnI antibodies (detecting epitopes at amino acids 41 -49 and after amino-acid residue 110 in the C-terminal part) immobilized to a streptavidin-coated single microtitre well.…”