How does SPR work? By exciting and detecting collective oscillations of free electrons, called surface plasmons, in a metal film. There are several ways to achieve this excitation and detection. A widely used one is the Kretschmann configuration, in which light is focused onto the metal film through a glass prism and the reflection of the light is detected (Fig. A). At a certain incident angle (resonance angle), the plasmons are set to resonate with light, resulting in absorption of light at that angle, creating a dark line in the reflected beam (Fig. B). That dark line contains a wealth of information. A molecular binding event taking place on or near the metal film, or a conformational change in the molecules bound to the film causes a shift in the resonance angle. By monitoring the shift vs. time, researchers can monitor molecular binding events and study the kinetics of the binding without labels (Fig. C).

BI-SPR Technology . Flow Injection SPR . Electrochemical SPR
Gas Phase SPR . Technical Notes