Objective

Label-Enhanced SPR (LE-SPR) significantly improves both the sensitivity and the specificity of Surface Plasmon Resonance analysis. LE-SPR can be used directly on standard Biacore™ instruments without any modification of the existing instrument hardware.

LE-SPR is based on labelling of one interactant with specialized dye labels combined with software-based curve shape analysis of the entire SPR dip curve. In this way, an extremely sensitive and fully specific measure of the binding of dye-labelled compound is obtained and plotted as an enhanced sensorgram or ‘epigram’.

For the analysis of small molecules and fragments, LE-SPR offers a 100-fold sensitivity increase as compared to conventional SPR. Further, the high specificity allows removal of most sources of background signal, e.g. bulk disturbances like varying DMSO concentrations.

For large biomolecules, there is also a significantly improved detectability due to the high specificity that allows removal of background signal from e.g. non-specific binding of sample components.

We will explain the basic theory of LE-SPR, and show applications within small molecule analysis as well as protein analysis. We will also show the simultaneous and selective monitoring of two binding species using LE-SPR, which in effect corresponds to performing dual-colour analysis on a standard SPR instrument.