The Surface Plasmon Resonance (SPR) is an optical technology for monitoring specific binding events between two or more bio-molecules without the use of labels. For recent 10 years, its reliability has been proven within life science applications.
The SPR signal originates in changes in the refractive index at the surface layer, caused by concentration changed on the sensor chip surface with adsorbed bio-molecules.
The SPR is detected by measurement of the intensity of reflected light. From the SPR angle, a sharp decrease or dip in intensity can be measured.
Any change in thickness or index of refraction of the material adsorbed onto gold surface results in a shift of the SPR angle. The SPR angle shift is used as a response unit to quantify binding molecules to the sensor surface.