What is SPR Surface Plasmon Resonance?

A biosensing technique in which biomolecules capable of binding to specific analytes or ligands are first immobilized on one side of a metallic film. Light is then focused on the opposite side of the film to excite the surface plasmons, that is, the oscillations of free electrons propagating along the film's surface. The light reflecting off this surface is measured at a specific angle, the surface plasmon resonance (SPR) angle.

When the immobilized biomolecules are bound by their ligands, an alteration in surface plasmons on the opposite side of the film is created which is directly proportional to the change in bound, or adsorbed, mass. Monitoring of the SPR angle provides a real time measure of chnges in the surface concentration. The technique is used to study biomolecular interactions, such as antigen - antibody binding.

Biacore systems define the characteristics of proteins in terms of their specificity of interaction with other molecules, the rates at which they interact (binding and dissociation), and their affinity (how tightly they bind to another molecule).

Biacore systems provide sensitive, accurate concentration measurements. This is based on the ability of the biomolecule of interest to interact with a specific binding partner, and may therefore be more informative than generic measurement techniques (total protein concentration for example).