Surface Plasmon Resonance

Surface Plasmon Resonance (SPR) is an optical detection process that occurs when a polarized light hits a prism covered by a thin planar metal (typically gold or silver) layer. At certain angles of incidence, a portion of the light energy couples through the gold coating and creates a surface plasmon wave at the sample and gold surface interface. The angle of incident light required to sustain the surface plasmon wave is very sensitive to changes in refractive index at the surface (due to mass change), and it is these changes that are used to monitor the association and dissociation of biomolecules.