Cheat sheet: Static and Kinetic SPR

A quick-reference guide to the two core SPR measurement modes — when to use each, what data you get, and how to interpret the results.

Main Differences

Static SPR

Purpose: Scouting or screening prior to Kinetic SPR, yes/no binding.

• Like label-free ELISA: ligand-analyte interaction depends on diffusion, concentration, and binding strength measured as Apparent K_D
• Concentration determination of active analyte in complex media (e.g. crude lysate)
• Quick verification of protein expression
• Contact time ~ seconds to hours so slow interactions can be measured with Static SPR
• Low viscosity buffers and biomolecules 10–500 kDa are recommended
• Up to 4 independent experiments (4 channels) for P4 SPR device

Flow (Kinetic) SPR

Purpose: Sensitive, quantitative binding characterization.

• Constant flow of analyte enables ligand-analyte interaction so both strength and rate of binding are measured as Quantitative K_D
• Can transfer Static SPR conditions to Kinetic SPR
• Due to controlled flow, Kinetic SPR can accommodate a broader range of molecule sizes (100+ Da)
• Suitable for low analyte concentrations, better real-time sensitivity

Data Output Differences

Static SPR Data

• Association without dissociation
• End-point response units are analyzed
• Like ELISA, Apparent K_D can be estimated at ½ RU max determined by concentration titration

Flow SPR Data

• Both association and dissociation
• Quantitative K_D calculated by k_off/k_on
• Steeper upward curve → faster association
• Steeper downward curve → faster dissociation