Bio-layer interferometry

Bio-layer interferometry (BLI) is an optical biosensing technology that analyzes biomolecular interactions in real-time without the need for fluorescent labeling.

[1] Alongside Surface Plasmon Resonance, BLI is one of few widely available label-free biosensing technologies, a detection style that yields more information in less time than traditional processes.

[2] The technology relies on the phase shift-wavelength correlation created between interference patterns off of two unique surfaces on the tip of a biosensor.

[1] The biosensor tips themselves are transported directly to the desired sample and "dipped" into their respective compartment, eliminating the needs for micro-fluidics and the complications (clogging, purification) that come with it.

[8] This distinct detection method ensures that sample concentration and viscosity and varying refractive indexes rarely affect the results of BLI.

For BLI calculations to work, it is necessary to assume that both the fiber optic tip and the bound ligand and analyte act as thin, reflective surfaces.

Where the traditional Electrophoretic Mobility Shift Assay (EMSA) method can be used, BLI can act as a suitable substitute if the provided benefits (label-free, real-time measurements) are desired.

The benefits that BLI brings provide additional insight into kinetics on top of commonly used endpoint methods like enzyme-linked immunosorbent assay (ELISA).

[1] Interference patterns found in BLI experiments can be used to calculate rate constants and other kinetic data in biomolecular interactions.

Figure 1 - Overview schematic of a Bio-layer interferometry setup
Figure 2 - The ligand-analyte layer creates an optical path length difference, reflecting incident light in two different patterns
Figure 3 - Reflectance signal as a function of wavelength
Figure 4 - Overview schematic of Surface Plasmon Resonance