Use of capillary electrophoresis-based competitive immunoassay for a large molecule

Area of Science:

• Analytical Chemistry
• Biochemistry
• Immunology

Background:

• Capillary electrophoresis-based immunoassays (CEIA) are analytical techniques for detecting and quantifying analytes.
• Traditional UV detection in CEIA can suffer from poor resolution of immunocomplexes.
• Optimization is needed to improve the sensitivity and accuracy of CEIA for protein quantification.

Purpose of the Study:

• To optimize capillary electrophoresis-based immunoassay (CEIA) for the quantification of bovine serum albumin (BSA).
• To evaluate the impact of different detection methods and assay configurations on CEIA performance.
• To demonstrate the application of competitive CEIA for high-molecular-mass protein quantification in biological fluids.

Main Methods:

• Systematic optimization of CEIA parameters including voltage, pH, and ionic strength.
• Utilized fluorescein isothiocyanate-labeled BSA (FITC-BSA) as a tracer with laser-induced fluorescence detection.
• Compared performance in uncoated and coated capillaries using whole or Fab fragment of monoclonal anti-BSA.

Main Results:

• Laser-induced fluorescence detection achieved well-separated peaks for free and bound FITC-BSA, unlike UV detection.
• Optimized buffer conditions (voltage, pH, ionic strength) enhanced the separation of immunocomplexes.
• Coated capillaries demonstrated a lower coefficient of variation for BSA quantification compared to uncoated capillaries.

Conclusions:

• Fluorescence detection significantly improves the resolution and quantification capabilities of CEIA.
• Competitive CEIA, particularly with coated capillaries, offers a robust method for accurate protein analysis.
• This optimized CEIA approach is suitable for quantifying high-molecular-mass proteins in complex biological samples.