The concentration of an analyte can be determined directly using SPR. In this example, anti-human serum albumin mouse monoclonal (Anti-HSA) was immobilized directly to the XanTec CMD500m dextran sensor chip at a high level (greater than 1500 micro RIU). A range of antigen concentrations (human serum albumin or HSA) was injected over the surface and was expected to encompass the concentration in the unknown samples. The high surface concentration of antibody created a diffusion controlled binding response where the initial response was proportional to the concentration of the injected antigen analyte. In this example, the response at 90 seconds was plotted against the concentration of injected HSA creating a standard curve so that the concentration of HSA in unknown samples could be calculated. Known control samples were also injected.
The experimental conditions are summarized in the following table:
The 2SPR system monitors this antibody-antigen interaction in real-time with simultaneous measurements of sample and reference channels.