ProteOn XPR36, User Manual

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ProteOn XPR36 System
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Appendix
C Surface Plasmon
Resonance
The ProteOn™ XPR36 protein interaction array system is a multiplex optical
biosensor that monitors biomolecular interactions through surface plasmon
resonance (SPR). This system is capable of simultaneous measurement of as
many as 36 individual interactions. It integrates a high-efficiency microfluidics
system with a high-sensitivity optical system to generate data from a unique 6
x 6 interaction array for analyzing up to six ligands with up to six analytes.
The detection principle of the ProteOn XPR36 system is based on SPR
measurement. SPR is an optical effect that, in the ProteOn XPR36 system,
occurs on the surface of a thin layer of gold that coats a high refractive index
glass prism (the sensor chip). The SPR effect is extremely sensitive to the
mass of materials in the proximity of and/or bound to the chip's gold surface
layer. This sensitivity is expressed as a shift of the minimum of an optical
reflectivity curve. The mass of the material depends on the refractive index of
the liquid near the surface (within less than 1 μm). This bulk effect, in turn, is
proportional to the concentration of molecules in the liquid and the refractive
index of the liquid. Any bound molecules also change the mass of the
material, and hence change the effective index of refraction at the surface.
The ProteOn XPR36 system achieves high-quality, real-time monitoring of the
SPR response measurements over the entire 6 x 6 array with the speed and
sensitivity required for biomolecular applications.
Biomolecular Applications
The ProteOn XPR36 system tests multiple conditions and/or samples in
parallel to collect a full kinetic dataset without a regeneration step—the
principle of One-shot Kinetics™. With One-shot Kinetics, the ProteOn XPR
system can compare interaction conditions (to optimize sensor chip activation
levels, pH conditions, and the like) and analyze multiple protein interactions (a
single ligand immobilized at different levels interacting with an analyte
concentration series, or a ligand set interacting with an analyte concentration
series).
Protein interaction studies generate the following types of data:
• Specificity and identity — qualitative “yes/no” binding for ligand
and analyte, identification of interacting partners