Bio-Layer Interferometry (BLI) is a label-free, real-time monitoring optical detection technique for the full range of quantitative analysis of biomolecular interactions and protein concentration determination. BLI is widely used in the biopharmaceutical industry and academic research.

BLI enables real-time monitoring of the entire intermolecular binding process and calculates important data such as the affinity (kd), binding rate (ka) and dissociation rate (kd) between molecules. BLI can detect various types of samples such as proteins, nucleic acids, polysaccharides, lipids, small molecule drugs, antibodies, viruses, bacteria and cells. The technology has been widely used in life science research fields such as protein structure target analysis, drug development and screening, immunology, gene regulation, signaling pathways, genetics, microbiomics, virology, nanoparticles, liposome and natural product analysis.

What Can BLI Offer?
Observation of the assembly process of protein complexes
Screening of molecular markers in tumors
Analysis of nucleic acid-protein interactions
Detection of viral particle-protein and protein-protein interactions
Identification of the titer of a trace protein in vaccines and vaccine development
Affinity and kinetic determination of antibodies and small molecule drugs
Screening of small molecule compounds (antibodies), etc.
Principle of BLI
BLI uses fiber optic biosensors to detect changes in the thickness of the optical layer of the sensor when molecules bind and dissociate in real time. The binding of biomolecule A to the end of the sensor results in a biofilm. When molecule A binds to molecule B to be detected, it causes a change in the molecular weight at the end of the sensor, resulting in a change in the thickness of the biofilm. Light passing through the biofilm layer of the sensor is transmitted and reflected to form interfering light waves, and the change of biofilm thickness leads to the relative displacement of the interfering light waves. The interferometric light waves before and after the binding of biomolecules are detected by the spectrometer to form an interference spectrum, which is displayed as a real-time displacement (nm) of the interference pattern. Finally, the molecules to be detected are analyzed according to the changes in the maps before and after molecular binding.

Principle of the ForteBio BLI technique (Wallner et al., 2013)

Advantages of BLI
No labeling required
Real-time data monitoring: real-time molecular interaction kinetic data can be detected
Low detection dosage: only a small nanomolar amount of sample is required, which can be used to analyze molecular samples that are difficult to separate
Wide range of applications: direct detection of crude samples, even the presence of insoluble components in the sample, resistant to a variety of solution environments, only molecules bound to the surface of the sensor will be detected
High throughput detection, easy and fast experimental process
Accurate results: fine quantitative analysis and acquisition of kinetic parameters for more biological information
Disadvantages of BLI
Need to fix the ligand to the tip surface
Lower sensitivity (detection sensitivity is 100 times lower than SPR)
Octet BLI Unlabeled Detection System
High throughput – protein quantification in just two minutes and the ability to process up to 96 samples simultaneously on the Octet HTX system.

Broad sample compatibility – analytes can be measured in unpurified mixtures such as cell lysates or hybridoma supernatants. the Octet system can tolerate glycerol and even up to 10% DMSO.

Lower overall cost – no flow module blockage problems and waiting time for parts replacement due to downtime.

Reference

Wallner, Jakob, et al. “Application of Bio-Layer Interferometry for the analysis of protein/liposome interactions.” Journal of pharmaceutical and biomedical analysis 72 (2013): 150-154.
Related Service
Biolayer Interferometry (BLI)