Gradient fluidics

To simplify experimental design, proprietary fluidics has been developed. 

The proprietary fluidics, cuvette injection flow (CIF), of the SPR imager of Vysens enables to inject samples directly from a cuvette which is placed on top of a two-channel flow cell. Without applying an air bubble to separate the running buffer from the sample the analyte can be injected instantly into the flow chamber without delay. Large particles, e.g. cells can be injected without clogging the fluidics. The position of the optics allows to apply sedimentation of the cells. In order to keep the sample volume low e.g. 50 µl back and forth flow is applied to reduce the sample volume while association times can be e.g. half an hour. The CIF is applied to generate the ligand density gradient in both flow channels.

The analysis of the kinetics of biomolecular interactions carried out with current commercial instruments is complicated, needs expertise and cannot be easily automated. As the ligand density of an antibody captured to the sensor surface is tuned by an experienced scientist in high-end instruments to obtain affinity values at Rmax = ~100, these values are considered to be reliable. But it costs time and a number of sensor chips to optimize the ligand density in a trial and error experiment. In SPR imaging instruments with off-line spotting, the ligand density cannot be tuned but investigated only after spotting.

Schermafbeeldin CIF

When a gradient of ligand density is immobilized on the sensor surface, it is possible to measure simultaneously concentration and affinity data in one fully automated run. With the new plug and play method an unexperienced user will generate highly accurate functional concentration and reliable affinity parameters of the ligand-analyte interaction from a single experiment.