Rapid homogeneous immunoassay for cardiac troponin I using switchable lanthanide luminescence

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Biochemistry

Background:

• Homogeneous assays offer simplicity and speed but often lack the sensitivity of heterogeneous assays.
• Traditional homogeneous immunoassays struggle with compromised performance compared to their heterogeneous counterparts.
• Developing sensitive and rapid homogeneous assays remains a significant challenge in diagnostics.

Purpose of the Study:

• To develop a high-performance homogeneous immunoassay using switchable lanthanide luminescence.
• To improve assay sensitivity and kinetics by employing site-specifically labeled recombinant antibody fragments.
• To demonstrate the potential of switchable lanthanide luminescence for advanced immunoassay development.

Main Methods:

• Utilized switchable lanthanide luminescence for signal generation, dividing the chelate into non-luminescent moieties.
• Employed site-specifically labeled recombinant antibody fragments for specific binding to cardiac troponin I.
• Developed a self-assembly mechanism where analyte recognition brings label moieties together to form a luminescent complex.

Main Results:

• Achieved elimination of assay background through the switchable luminescence mechanism.
• Maximal signal-to-background ratios were obtained within 6 minutes, indicating rapid assay kinetics.
• The limit of detection for cardiac troponin I was 0.38 ng/mL (16 pM), comparable to heterogeneous assays.

Conclusions:

• This work presents the first application of switchable lanthanide luminescence in immunoassays.
• The developed homogeneous immunoassay demonstrates versatile potential for rapid and sensitive diagnostic applications.
• The technology offers a promising alternative for improving homogeneous assay performance.