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Protein Sciences

Uniting Drug Development Expertise with Antibody & Protein Production Services

Surface Plasmon Resonance (SPR) and Bio-Layer Interferometry (BLI) Binding Assays

SPR and BLI Analysis

SPR and BLI binding assays are optical techniques used to monitor and analyze real-time interactions between biomolecules, providing valuable insights into binding kinetics, affinities, and more.

SRP and BLI binding assays that monitor and analyze real-time interactions between biomolecules.

Applications of BLI/SPR

SRP and BLI binding assays can be applied to compounds, nucleic acids, proteins, lipids and viruses.

Surface Plasmon Resonance (SPR)

SPR is an optical method used to monitor real-time molecular interactions. This occurs when plane-polarized light interacts with a metal film under specific reflection conditions (total internal reflection).

Benefits of SPR:

 

  • Versatile: Capable of detecting most types of molecules
  • Wide range: Analyze bound molecules at μM to fM levels

SPR is a real-time, label-free method of sensitive detection of molecules interactions.

SPR (Biacore)-based Binding Assay Service Details

SPR Services Description Duration Request A Quote
Target binding affinity measurement Assay development and measure kinetics/affinity for 1 interaction 1~2 weeks Request A Quote
Off-rate ranking Assay setup and off-rate testing using single concentration for 1 interaction 1~2 weeks
Fc receptors binding Full panel of Fc receptors (FcγRs, FcRn and human C1q) binding for 1 sample 2 weeks
Epitope binning 2-direction measurement for 8×8 pair by Biacore 2 weeks
2-direction measurement for high throughput testing by Carterra 2-3 weeks for 40×40 pair; TBD for more
Simultaneous binding for bispecific antibody Assay development and testing for 1 sample 1~2 weeks

Case Study: SPR’s Diverse Analysis Capabilities

 

This case study demonstrates the core capability offered by SPR for determining binding kinetics, affinities, epitope binning, and concentration analysis.

Figure A: Presents a distinct kinetic binding pattern resulting from the interaction between an antibody and antigen. This data set shows a strong representative example of an analyte with high affinity to its target.

Showcase an analyte with high affinity to its target with SPR assays.

Showcase the effectiveness of epitope binding through SPR.

Figure B: Shows the effectiveness of epitope binning through SPR. A secondary antibody (blue) was introduced after the formation of an antibody-antigen complex. A competing antibody was tested in parallel (red). This figure indicates that the two antibodies possess distinct epitopes that don’t overlap.

Figures C & D: Shows the concentration analysis of an analyte with and without calibration.

Showcase the concentration analysis of an analyte with and without calibration.

Bio-Layer Interferometry (BLI)

BLI is a label-free optical method that provides real-time measurements of changes in optical thickness at a biosensor’s surface. It achieves this by analyzing the interference patterns created when a light beam reflects off the biosensor’s surface and the biomolecular layer on top of it. The strength of the signal directly relates to the size of the molecule bound to the sensors.

BLI (octet)-based Binding Assay Service Details

Activity-Part Description Duration Request A Quote
Assay development Single assay condition, single sensor type, affinity/kinetics profile for the target, 1 interaction included 1-2 weeks Request A Quote
Measurement Based on established assay conditions, measure the affinity/kinetics for 1 interaction 1-2 weeks
Screening Single concentration, response level and off-rate will be provided (if applicable)

<150 Interaction:

1-2 weeks

>150 Interaction:

TBD

Figures A & B: Demonstration of the fast and accurate titer measurements obtained with BLI, with pre-setup calibration curve. 

Showcase the fast and accurate titer measurements obtained with biolayer interferometry (BLI).

Showcase the fast and accurate titer measurements obtained with biolayer interferometry (BLI).

Summary of BLI & SPR Capabilities

  BLI SPR
Data measurement Real-time Real-time
Detection Label No No
Sensitivity KD: nM to μM KD: pM to μM
Molecular type Most types of molecules Most types of molecules
Amount 200~300 μg 200~300 μg
Sample buffer restrictions None No Sucrose, Glycerol etc. (RI different with water)
In vivo/In vitro In vitro, Directly binding In vitro, Directly binding

 

Frequently Asked Questions for our SPR & BLI Binding Assay Services

Q: Which binding method is chosen for different stages of the experiment?

A: Our BLI instrument, with up to 32 channels in parallel, is ideal for initial screening with fewer analyte concentrations (typically single concentration). SPR, with its 3-8 channels in parallel, is more sensitive than BLI and is suitable for both screening and characterization.

Q: For SPR experiments involving antigen and antibody, how do you decide which is the ligand?

A: Typically, the antibody will be the ligand as it can be easily captured by specialized reagents, such as anti-human Fc antibodies. This approach requires less assay development effort and ligand activity is often well-maintained. In certain circumstances where capturing the antibody might not be applicable, or if no antibody is involved, the orientation will be reversed or redesigned.

Q: How are the concentrations chosen for SPR experiments, and what are the molecular weight requirements?

A: We start with a middle concentration and adjust based on the results. The concentration should ideally cover 1/10 of KD to 10× KD. Higher molecular weights yield higher responses, but with Biacore, we can easily test low molecular weight molecules with lower signals.

Q: Can you measure protein binding to small molecules and peptides in binding experiments?

A: Yes, we can. With Biacore, we can easily test low molecular weight molecules. However, for weak binders with fast-on and fast-off binding profiles, kinetics with on-rate and off-rate might not be available and only steady-state fitting will appear in the report.

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