Biolayer Interferometry (BLI), Isothermal Calorimetry (ITC), Microscale Thermophoresis (MST) and Surface Plasmon Resonance (SPR) can all be used to study biomolecular interactions. The four techniques and their advantages/disadvantages are summarized here and in our white paper.
As you read further, you will find that SPR provides the most complete information about the biomolecular interaction being studied of the instruments compared.
Biolayer Interferometry (BLI) involves the use of white light interferometry to quantify biomolecules which are typically adsorbed to the tips of optical fibers. Advantage: the medium surrounding the sensor does not influence the signal so no reference channel is needed. Disadvantage: BLI has approximately 100-fold lower sensitivity of detection, making it difficult to follow the binding of small molecules.
Isothermal Calorimetry (ITC) is used for quantitative thermodynamic characterization of a wide variety of biomolecular interactions by directly measuring the heat that is either released or absorbed during binding. Advantages: ITC can determine all thermodynamic binding parameters in a single experiment in their unmodified state. Disadvantages: kinetics (association and dissociation rate constants) cannot be determined. This low-throughput method requires more sample than similar techniques.
Microscale Thermophoresis (MST) is performed using thin capillaries in free solution, comparable to ITC measurements. Advantages: MST requires only a small amount of sample and the technique is relatively easy to use. Disadvantages: the requirement to use hydrophobic fluorescent labels adds to the overall experimental process and these labels have been known to cause non-specific binding. Also, MST cannot provide kinetics information (association and dissociation rates).
Surface Plasmon Resonance (SPR) is a label-free method capable of measuring real-time quantitative binding affinities, kinetics and thermodynamic parameters of interacting molecules. It has the most advantages compared to the other techniques in that SPR provides the highest quality data, with moderately high throughput, while consuming relatively small quantities of sample.