Compatibility with complex samples

Get rid of ‘bulk effect’ and separate true binding without a reference channel!

Differences in liquid composition between samples and running buffer causes a change in refractive index, which in turn appears as a shift in the measured SPR curve. This is called bulk effect, and it is present with any method that records refractive index changes close to a sensor surface.

In traditional SPR, imaging SPR or localized SPR, meticulous bulk signal calibrations with multiple background solution injections and a dedicated reference channel are required to separate true molecular binding from the undesired bulk effect, and only small changes in concentrations of the solvent (e.g. DMSO) are allowed.

Bulk effect is not an issue with MP-SPR instruments, because the complete SPR curve measurement capability  enables cross-correlation of parameters provided by the MP-SPR method and allows simple in line characterization of interfering bulk signal using the PureKinetics™ feature. This feature is available in all MP-SPR Navi™ instruments.



PureKinetics™ improves the reliability of results by allowing the real binding signal to be distinguished. It offers significant advantages, especially when a reference flow cell is not available due to sample or sensor surface properties, or when high concentrations of additives (such as DMSO for solubility) are required in the experiment. PureKinetics™ is particularly effective for studying lipid bilayer or material-biomolecule interactions, where fabricating a reference channel is challenging. It is also crucial for measurements performed in crude samples.

Further reading: 

Application Note #151 MP-SPR measurements of soft and hard corona on nanoparticle in 100% serum

Application Note #147 Analyzing dissociation kinetics of IgG from protein A using MP-SPR and PureKinetics™

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