Surface Plasmon Resonance SPR

SPR refers to an optical technique which is a very popular detection scheme in biosensors. It is most commonly not used to study the surface itself, but rather to study the interaction of a solute with a reaction partner that has been immobilized at the surface. The principle of SPR is illustrated in Fig. 2. A laser beam is coupled into a high refractive index glass prism and totally internally reflected off its base. The reflected beam is then detected outside the third side of the prism. The base is coated with a thin metal layer (usually gold) and SPR exploits the peculiar physics of total reflection. Instead of being strictly reflected at the edge of the glass prism, 

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There are a few other surface-sensitive characterization techniques that also rely on the use of lasers. For instance surface-plasmon resonance (SPR) measurements have been used to follow changes in surface optical properties as a fiinction of time as the sample is modified by, for instance, adsorption processes [ ]. SPR has proven usefiil to image adsorption patterns on surfaces as well [59]. 

Surface plasmon resonance (SPR) Interaction strength (molar dissociation constant, K ). One member of the reacting pair needs to be immobilised onto an inert surface. Not suitable for selfassociation analysis. [7]... 

Hartmann T, Ober D (2000) Biosynthesis and Metabolism of Pyrrolizidine Alkaloids in Plants and Specialized Insect Herbivores. 209. 207-243 Haseley SR, Kamerling JP, Vliegenthart JFG (2002) Unravelling Carbohydrate Interactions with Biosensors Using Surface Plasmon Resonance (SPR) Detection. 218 93-114... 

The affinity (interaction strength), multiple interactions, and the changes in concentration can be also monitored from those studies. To deliver data in real time, the natural phenomenon of surface plasmon resonance (SPR) is employed. Since the refractive index (r ) at the interface changes as molecules are immobilized on the sensor surface, instant measure of r provides real-time assessment. The Tlcxchip platform exploits grating-coupled SPR (GC-SPR) for this purpose. 

The introduction of optical biosensors has made it possible to obtain data for a large number of macromolecular interactions without the necessity of additional labeling. Here several commercial instruments utilize the effect of Surface Plasmon Resonance (SPR) to detect accumulation of ligands in the sensor matrix. 

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