Effect of hydrogel matrix on binding kinetics of protein-protein interactions on sensor surface

Surface plasmon resonance (SPR) biosensor has become a standard technology for measuring kinetics of bimolecular interactions without the need for labeling. Sensor chips coated with a carboxymethylated dextran (CMD) hydrogel matrix are commonly used for immobilizing a protein binding partner in kinetic studies. The sensor chip provides a biocompatible surface with low non-specific binding, but it also presents some problems, such as steric effect and re-binding which may bias the kinetic measurement. In the present study, the effect of hydrogel matrix on protein-protein interaction was investigated. The insulin-like growth factors (IGFs) and their binding proteins were used as the model system. Kinetic parameters obtained with either of the binding partners immobilized on the matrix were compared to evaluate the effects of the matrix on the binding kinetics. The surface capacity and sensitivity of the hydrogel-modified sensor chip (CM5) and those of a sensor chip modified with a self-assembled monolayer (SAM) were measured and the performance of both chips was discussed.