The detection of a specific molecule in a complex sample (cell extract, serum, milk…) can be performed by immobilizing a binding partner on the biochip.

The SPRi difference image gives a direct Yes/No answer of the binding. When injecting the sample, interacting spots appear as white on the SPRi difference image. The detection of the interaction is label-free, no need to modify your molecules.

The affinity (KD) of the interaction describes the strength of binding. However, similar affinities can result in different kinetics. The determination of the kinetic parameters from the sensorgrams (association ka and dissociation kd rates) better characterize the molecular interaction.

Unlike end-point measurements such as ELISA, SPR imaging allows the monitoring in real-time of the molecular interaction, providing information on the kinetics parameters. The high-throughput of SPR imaging allows the parallel analysis of multiple molecules immobilized on the biochip surface.

The active concentration of a biomolecule in a solution can be easily obtained using a specific binding partner. Because the measurement is based on the affinity interaction between the binding partners, the measured concentration is not influenced by sample heterogeneity (protein folding, aggregation…). In addition, with SPR imaging, the measurement is fast (typical assay time: < 10 min).