Kinetic analysis of antibody-antigen interactions using phase-detection-based surface plasmon resonance sensor system

Surface plasmon resonance (SPR) biosensors have the advantage of being highly sensitive, requiring no fluorescent-labeled analytes or receptors, and being capable of monitoring molecular interactions in real time. Thus, they have been widely used in determining the dynamics of molecular interactions. However, owing to the lack of experience in employing phase-detected SPR, there have been no research reports on the determination of affinity constant for antigen-antibody interactions. In this study, we used a custom-made phase-detection SPR sensor system to investigate the kinetic parameters of an antibody binding to an antigen immobilized on a CM5 sensor chip. This system provided real-time measurements of molecular interactions on the sensor chip. The association and dissociation rate constants and the corresponding affinity were obtained,