Europium Complex-Loaded Albumin Nanoparticles as Probes for Time-Resolved Luminescent Immunoassay

Area of Science:

• Biomaterials Science
• Analytical Chemistry
• Immunotechnology

Background:

• Immunoassays are crucial for disease diagnosis and monitoring.
• Existing methods like DELFIA assays often require signal enhancement steps.
• Development of novel labeling strategies for enhanced immunoassay performance is ongoing.

Purpose of the Study:

• To develop and validate albumin nanoparticles loaded with luminescent europium complexes for immunoassay applications.
• To evaluate the performance of these nanoparticles as labels in a time-resolved immunoassay for human IgG detection.
• To compare the developed assay with commercial immunoassay kits.

Main Methods:

• Albumin nanoparticles synthesized via desolvation, loaded with europium complexes, and functionalized with streptavidin.
• Application of nanoparticles as labels in a sandwich time-resolved solid-phase immunoassay.
• Detection of human IgG in serum samples using time-resolved fluorescence detection.

Main Results:

• Nanoparticles exhibited uniform morphology, hydrodynamic diameter of 263 nm, and strong luminescence at 615 nm.
• The immunoassay showed a tenfold increase in signal intensity and a two-order reduction in background compared to conventional methods.
• The assay demonstrated high sensitivity, detecting human IgG at dilutions up to 1:100,000 with minimal cross-reactivity.
• Strong concordance with commercial immunoassays was observed, with suboptimal intra-assay reproducibility as a limitation.

Conclusions:

• Albumin-europium nanoparticles represent a promising, label-free approach for sensitive immunoassay development.
• The intrinsic luminescence of the nanoparticles simplifies assay procedures by eliminating signal enhancement steps.
• Further optimization is needed to address assay reproducibility challenges for widespread clinical application.