Biolayer Interferometry (BLI) Service

  • Service Details
  • Case Study

Introduction of Biolayer Interferometry (BLI)

Biolayer interferometry (BLI) is a label-free optical technology used to measure intermolecular interactions. It has the advantages of high sensitivity, high throughput, and low vibration/mechanical noise. This technology uses a biosensor with a coated tip (biological layer), immobilizes the bait molecule on the sensor, and then exposes the biosensor tip to buffer conditions and light to monitor the target molecule in real time by recording changes in light interference. The interaction between the analyte and the bait is directly related to the change in the thickness of the biological layer caused by the association of the analyte. The change in the refractive index of the surrounding medium, the change in flow rate, and unbound molecules will not affect the interference pattern. BLI can provide protein binding and quantitative information, as well as kinetic information about the affinity and stability of the interaction.

Biolayer Interferometry (BLI) technology assay principleFigure 1. Biolayer Interferometry (BLI) technology assay principle (Concepcion, J.; et al. 2009)

Selection of Biosensors

When BLI is applied to kinetic constant determination experiments, commonly used biosensors mainly include SA, SSA, AR2G, APS, AHC and AMC, etc. Each biosensor is applicable to different biological samples, and the requirements for the use of different biosensors are also different. For example, SSA is only suitable for detecting small molecule samples. SA is used to cure biotinylated proteins, antibodies, compounds and nucleic acids to detect large molecules interacting with them, while AHC can directly cure human antibodies to detect interacting molecules.

BLI Service in Creative Proteomics

Biolayer Interferometry (BLI) Platform

Creative Proteomics has been focusing on the research of molecular interactions for nearly two decades. The rich experience and outstanding insights have made us a biotechnology company trusted by researchers all over the world. The BLI technology platform we established is jointly managed by professional BLI technicians and molecular biologists. Our professionalism and dedication have won us a lot of praise.

  • Our platform includes FortéBioOctet RED384 and BLItz instruments. Customers can choose specific equipment according to project requirements (sample size, molecular size, speed, etc.). Our professional technicians can guarantee the accuracy of the experiment.
  • This platform can conduct various researches, including protein quantification, kinetic determination, affinity determination, drug/antibody screening, drug development, etc. It can accurately and sensitively provide Ka, Kd ((kinetic binding), KD (equilibrium binding), and other data.
Application Area Details
Antibody/Antigen Fragment Analysis (1) Determination of ka, kd and KD values of antibody-antigen relationships
(2) Comparison of the affinity size of antibodies in crude extracts under various different production conditions
(3) Antibody protein engineering and affinity optimization
Protein-Protein Interaction (1) Structure/function correlation analysis
(2) Targeted mutation and kinetic correlation analysis
(3) Wild-type/mutant comparison
Protein-Nucleic Acid Interaction (1) Transcriptional analysis interaction analysis
(2) Relationship between RNA-binding proteins and RNA regulation
(3) Translational regulation mechanism
Protein-Lipid Interaction (1) Protein/micro follicle interaction analysis
(2) Analysis of membrane protein dynamics
Virus/Vaccine Research (1) Study of HIV membrane proteins
(2) Evolutionary analysis of virus selective binding capacity
(3) Research on the development of antiviral antibody drugs
Protein-Small Molecule Interaction (1) Detection of the lowest molecular weight limit of 150 Da
(2) Determination of binding constants ka, kd and KD values
(3) Rapid screening of a large number of drug libraries without additional labeling of molecules

Customers can choose different technology platforms according to project requirements, or contact us directly for consultation, and our expert team will provide you with customized experimental procedures.

Advantages of Biolayer Interferometry Service

Real-time Kinetic Data Acquisition: Enables dynamic data measurement for real-time detection of molecular interactions, including transient interactions.

Unique High-Throughput Platform: Capable of simultaneously analyzing 8 to 16 samples, making it the highest-throughput option among label-free technologies.

Minimal Sample Requirement: Requires only a small amount of nanomoles of samples, suitable for challenging molecular samples.

Wide Applicability: Directly analyzes crude samples, ensuring robust performance in various solution environments with selective detection.

High Sensitivity and Low Noise: Exhibits high sensitivity for accurate results in molecular interaction studies while minimizing vibration and mechanical noise.

Short Experimental Duration: Facilitates quick experimentation, ensuring efficient data collection.

Creative Proteomics is an international biotechnology company dedicated to the study of intermolecular interactions and other related fields. We have established an advanced biolayer interferometry technology platform that can supplement label-dependent methods to help customers study molecular interactions fast and in real time.


  1. Concepcion, J.; et al. Label-free detection of biomolecular interactions using biolayer interferometry for kinetic characterization. Combinatorial Chemistry & High Throughput Screening. 2009, 12: 791-800.
  2. Dzimianski, J.V.; et al. Rapid and sensitive detection of SARS-CoV-2 antibodies by biolayer interferometry. scientific reports. 2020.

Case Development and Validation of a Rapid BioLayer Interferometry Immunosorbent Assay (BLI-ISA) for Detection of SARS-CoV-2 Antibodies


The study aimed to introduce and validate a novel serological testing method, BioLayer Interferometry Immunosorbent Assay (BLI-ISA), for the rapid and efficient detection of SARS-CoV-2 antibodies in human plasma samples. The assay leverages the advantages of real-time data output, short assay times, and the potential for high-throughput adaptation compared to traditional methods like ELISA.


Two sets of samples were utilized - a pre-pandemic seronegative (SN) panel comprising 25 human serum samples collected in 2017 and two plasma samples from 2016, and a convalescent seropositive (SP) panel consisting of ten de-identified plasma samples obtained from individuals who had recovered from COVID-19.

Technical Methods

Reagents and Supplies

The study employed essential reagents, including PBS tablets, ELISA plates, antibodies, and cell culture components. Noteworthy items included phosphate-buffered saline (PBS) tablets (Sigma P4417), Tween-20 (Fisher BP337), and ChonBlock (Chondrex 9068). Recombinant SARS-CoV-2 spike proteins were expressed using a pCAGGS plasmid encoding the signal peptide and RBD of the spike protein. RBD-biotin and prefusion Spike-biotin were biotinylated in vitro using established protocols.

Recombinant SARS-CoV-2 Spike Proteins

The expression plasmid for the SARS CoV-2 spike RBD-His was obtained from BEI Resources. For RBD-biotin, the cDNA encoding the signal peptide, RBD, and 6XHis-tag was sub-cloned into pcDNA3.1, incorporating a Strep-tag and AviTag. CHO-S cells were transfected with purified DNA using flow electroporation. Transfected cells were cultured in CD OptiCHO medium supplemented with GlutaMAX, HT supplement, pluronic, and sodium butyrate. Purification of RBD-His involved affinity chromatography using a HisTrap column, followed by size-exclusion chromatography. RBD-biotin was purified using a StrepTrap column and subsequent dialysis.

Human Samples

The pre-pandemic seronegative (SN) panel comprised 25 human serum samples from 2017, obtained from the Lyme Disease Biobank. The convalescent seropositive (SP) panel included ten de-identified plasma samples purchased from AllCells. All samples underwent heat treatment at 56 °C for 1 hour before use.


ELISA plates were coated with RBD-His, blocked with non-fat milk, and incubated with diluted plasma/serum samples. The CR3022 antibody served as a positive control. Plates were washed, and goat anti-human IgG Fc HRP-conjugated secondary antibody was added. Substrate (OPD) was used for color development, and OD490 values were measured.

BioLayer Interferometry Immunosorbent Assay (BLI-ISA)

BLI-ISA studies were conducted on an Octet RED384 instrument at 24 °C with shaking. Anti-penta-His (HIS1K) or streptavidin (SA) biosensors were pre-hydrated in BLI assay buffer. The assay plate included columns for equilibration, antigen loading (RBD or prefusion Spike), washing, total antibody binding, and detection with anti-human IgG or IgA. Loading signals were measured, and Python scripts were developed for automated data analysis, determining total antibody binding and detection values.

Overview of the BLI-ISA experiment.Overview of the BLI-ISA experiment.


Antibody Detection: BLI-ISA successfully detected SARS-CoV-2 antibodies in plasma samples, allowing for the differentiation of seropositive and seronegative samples.

Comparison with ELISA: BLI-ISA results aligned with ELISA data, demonstrating its reliability as a serological testing method.

Advantages of BLI-ISA: The study highlighted the advantages of BLI-ISA, such as shorter assay times, no need for washing steps, and potential for high-throughput adaptation.

Application Potential: The method was deemed suitable for urgent SARS-CoV-2 serological testing needs, including serosurveillance studies and evaluating antibody responses to natural infection and vaccine candidates.

BLI-ISA evaluation of SARS-CoV-2 spike RBD reactivity of pre-pandemic and convalescent plasmaBLI-ISA evaluation of SARS-CoV-2 spike RBD reactivity of pre-pandemic and convalescent plasma

BLI-ISA evaluation of plasma antibodies to SARS-CoV-2 prefusion Spike and plasma IgA to SARS-CoV-2 spike RBDBLI-ISA evaluation of plasma antibodies to SARS-CoV-2 prefusion Spike and plasma IgA to SARS-CoV-2 spike RBD


  1. Dzimianski, John V., et al. "Rapid and sensitive detection of SARS-CoV-2 antibodies by biolayer interferometry." Scientific reports 10.1 (2020): 21738.
* This service is for RESEARCH USE ONLY, not intended for any clinical use.