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Evaluation of a method for affinity measurement using solution equilibrium titration with magnetic beads
Jeffrey M Schaub1, Isabel Ojeda1, Quinn A Best1
1Core Diagnostics R&D, Abbott, 100 Abbott Park Road, Abbott Park, IL, 60064-6016, United States.
Analytical Biochemistry
|June 30, 2026
Summary
A new method, solution-phase reaction, solid-phase detection (SRSD), estimates biomolecular binding affinities using magnetic beads. SRSD provides comparable results to traditional methods and works with unpurified analytes in complex mixtures.
Area of Science:
- Biochemistry and Molecular Biology
- Analytical Chemistry
- Biotechnology
Background:
- Antibody-antigen interactions are crucial in pharmaceuticals and diagnostics.
- Traditional affinity measurement methods like Solution Equilibrium Titration (SET) require detectable signal differences.
- Existing methods can be limited by the need for purified analytes or specific signaling.
Purpose of the Study:
- To evaluate a novel Solution-Phase Reaction, Solid-Phase Detection (SRSD) method for estimating biomolecular binding affinities.
- To compare the SRSD method against established techniques like Surface Plasmon Resonance (SPR) and SET.
- To assess the utility of SRSD for analyzing unpurified analytes in complex biological mixtures.
Main Methods:
- Development and application of the SRSD method using titrant-coated magnetic beads to detect free analyte.
- Comparative analysis of SRSD with label-free kinetic (SPR) and solution-phase equilibrium (SET) methods.
- Validation using two distinct antibody-antigen pairs and appropriate control experiments.
Main Results:
- SRSD yields apparent binding affinity measurements of the same order of magnitude as SPR and SET.
- The SRSD method demonstrated utility in complex mixtures with unpurified analytes.
- System-specific validation is crucial, as SRSD's applicability is situational.
Conclusions:
- SRSD is a promising method for estimating biomolecular binding affinities, particularly for unpurified analytes.
- The SRSD method offers an alternative approach to traditional affinity measurement techniques.
- Careful validation is necessary to ensure the reliability and appropriate application of SRSD across different biological systems.
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