- Biolayer Interferometry (BLI) is a label-free, optical biosensing technique used to monitor biomolecular interactions in real time. It is widely employed to study binding kinetics (association and dissociation rates), affinity, and concentration of biomolecules such as proteins, antibodies, nucleic acids, and small molecules. BLI is especially valuable in drug discovery, antibody characterization, and diagnostics due to its speed, precision, and ease of use.
- The core principle of BLI involves the interference of white light reflected from two surfaces: one is a stationary internal reference layer, and the other is the surface of a biosensor tip where a biological molecule (e.g., an antibody or antigen) is immobilized. When a binding partner in solution interacts with the immobilized molecule, the thickness of the biolayer on the sensor tip increases. This causes a measurable shift in the interference pattern of the reflected light, which is recorded as a wavelength shift (in nanometers). The magnitude of this shift correlates with the amount of bound material, allowing for quantitative analysis.
- One of the major advantages of BLI is that it does not require labeling of analytes with fluorescent or enzymatic tags, simplifying assay development. The system is also highly versatile, supporting a variety of immobilization chemistries and analyte types. Additionally, BLI allows for high-throughput screening when implemented on platforms with multiple biosensor tips, enabling rapid analysis of dozens or even hundreds of samples in parallel.
- Biolayer Interferometry is commonly used in the biopharmaceutical industry for antibody screening, epitope binning, and affinity ranking, as well as in academic research for studying molecular mechanisms and binding kinetics. Compared to other label-free techniques such as Surface Plasmon Resonance (SPR), BLI offers more flexible throughput and simpler instrumentation, making it a preferred choice for many laboratories.
