Technical Service

SPR Affinity Test


Our intermolecular interaction service is based on two systems, BiacoreTM and openSPR, which are based on the principle of surface plasmon resonance (SPR) technology, and are capable of rapid qualitative and quantitative analysis of intermolecular (protein-protein, antigen-antibody, protein and small molecule) affinity. Compared with traditional GST pull down, and immunoprecipitation, it has the advantages of higher sensitivity, detection throughput and lower sample requirements.

Surface Plasmon Resonance (SPR) affinity assay is an optically based, label-free assay for the real-time detection of molecular interactions between two or more molecules. SPR affinity assay is a method for detecting molecular interactions by tracking changes in the signal through a sensor chip. The SPR signal is presented as a change in the refractive index, which refers to a Response Unit (RU) approximately equivalent to the surface concentration of a protein at 1 pg/mm2 of protein surface concentration. Plotting the SPR signal over time during an interaction between two molecules produces a sensing map that can be visualized in real time (Fig. 1). A typical binding reaction consists of three phases: binding, equilibrium, and dissociation; fitting these sensorgram data to a mathematical model allows scientists to calculate association (Ka) and dissociation (Kd) rate constants and ultimately determine binding affinity (KD). Unlike isothermal calorimetry (ITC), which is based on equilibrium measurements of antibody binding affinity, SPR allows for complete kinetic parameters to assess all effects of binding and dissociation as well as antibody affinity.


1. Advanced platform for interaction analysis in basic research.

2. Real-time and label-free biomolecular interaction studies.

3. No molecular weight limitation for small molecules involved in interactions.

4. Wider range of kinetic parameters allows faster binding and slower dissociation.

5. 384 samples analyzed in one continuous injection

6. Smaller sample and target quantities (ug level)

7. Automation, high sensitivity, and high throughput


BiacoreTM System

Biacore technology is a new biosensing technology based on a physical optical phenomenon called surface plasmon resonance. With three major systems, Biacore 8K, BiacoreTM T200 (4-channel, 384 continuous injection) and SPR, AtaGenix can provide high-quality kinetic assay services.

Binding Capacity