This biosensor technology is based on the principle of surface plasmon resonance (SPR). This phenomenon occurs when polarized light, under conditions of total internal reflection, strikes an electrically conducting gold layer at the interface between media of different refractive index: the glass of a sensor surface (high refractive index) and a buffer (low refractive index). SPR is a powerful technique to detect the binding activity between all types of molecular interactions. This includes drugs and targets, antibodies and antigens or any pair of interacting molecules including protein-protein, protein-nucleic acid and protein-lipid interactions. Interactions are measured in real time allowing relative comparisons between different molecules or complete determination of kinetic parameters. Typically, a protein is bound to a ‘chip’ and analyte containing interacting components is examined. SPR does not require any type of labeling of the test molecules. Real time kinetics data is accomplished on the Unit BIAcore instrument. Quantitative information, such as kinetic parameters and equilibrium constants for complex formation can be obtained within a range of 100mM-1pM are analyzed with the BIAcore evaluation software.
Biacore systems characterize molecules in terms of:
specificity of their interactions
on and off rates constants (kinetics)
binding strength (affinity)