Surface Plasmon Resonance (SPR) is an established method for biomolecular interaction analysis. It is popular due to its sensitivity as well as its real-time and label-free measurement method. Multi-Parametric Surface Plasmon Resonance (MP-SPR) is based on SPR principle, however its advantageous optical setup measures a full SPR curve which enables new insight into interactions. For instance, PureKinetics™ function that provides measurements of small molecules, lipids and biomaterials without bulk effect (typical DMSO artefact). MP-SPR widens the application range of traditional SPR from small molecules up to nanoparticles and even living cells. Measurements can be performed even in complex media such as serum.
MP-SPR uniquely provides also information about layer properties. Thickness and refractive index (RI) data can be utilized in material characterization from Ångström thick layers up to micrometers or to ensure conformation of the molecules on the surface.
Above, you can see an animation of a full SPR curve scan. The speed is slowed down to show the principle in detail.
The top graph shows the SPR curve shift due to molecular binding at the SPR sensor (sometimes called SPR chip). The x-axis is the angle at which the laser excites plasmons. The y-axis shows the level of light intensity reflected from the surface. The dip in the curve (lowest light intensity) shows, when the plasmons are excited. Full SPR curves are used to obtain physical properties of the adsorbed sample.
Lower curve is a sensogram (sometimes called sensorgram). In this case, the angle of peak minimum from full SPR curve above, is plotted against time. Here, x-axis represents time, while y-axis shows the shift in angle at which the plasmons are excited. Sensograms are used to obtain kinetic information from the sample.