Surface plasmon resonance (SPR) is a phenomenon occurring at the interface of two media with different dielectric constants, such as a metal and a dielectric, wherein collective oscillations of conduction electrons are resonantly excited by, for example, p-polarized light. This excitation occurs under total internal reflection (TIR) conditions, giving rise to an evanescent field, and results in a dip in the reflected light intensity at a specific angle. This resonance angle is highly sensitive to the refractive index close to the interface and can thus be used to temporally probe e.g. binding events on the surface.

MP-SPR, or multi-parametric SPR, not only determines the SPR resonance angle, but records the full SPR curve including additional parameters such as steepest dip slope, dip intensity or the TIR angle, the latter enabling compensation of differences in bulk-refractive index. MP-SPR is applicable for layers up to micrometer thickness and is suitable for measuring various layer properties such as refractive index, absorption coefficient and thickness. 

Our instrument is a BioNavis MP-SPR NAVI 420A ILVES with four fluidic channels, two independent wavelengths for each channel and two sample loops. This allows for detection of thickness and conformation changes as well as KineticTitration.

Instrument properties:

• Model: MP-SPR NAVI 420A ILVES
• 4 fluidic channels
• 2 wavelengths: 670 and 785 nm
• Angular range: 40-78° internal reflection
• 2 injection loops, 250 μl
• Sample sources: 96 well plates, 7 auxiliary sample inlets
• Sensor size (width x height x thickness): 20 x 12 x 0.55 mm
   

Note: The instrument is only equipped with one sample syringe. Consequently, samples may not be run in parallel.