Antibody binding affinity measurement services

Antibody affinity form

Thanks to its unique antibody KD determination platform, ProteoGenix is THE reference in antibody affinity measurement. Measuring interactions with cells, bacteria, proteins in native conformation or performing high throughput KD determination is now made possible thanks to our 3 technologies! Send us your requirements and our PhD account managers will outline the best solution to meet your accuracy/price/timeline expectations.

Why choose ProteoGenix for your
antibody KD determination?

Antibody KD measurement competitive price
Competitive price

We guarantee the lowest price on the market!

3 antibody affinity determination technologies
3 different complementary technologies

Antibody affinity measurement by SPR, SPRi or Octet.

Antibody cell affinity measurement
An unique antibody-cell affinity measurement service

Even compatible with high throughput KD determination.

SPRi KD determination
State-of-the-art equipment

We are one of the only service providers proposing antibody KD determination by SPRi.

Label free antibody KD value measurement
Label free measurement

No additional lead time, no extra cost, no artifact or bias (occluded binding site, false hydrophobic interaction)

Antibody affinity measurements experts
PhD account managers

Need advice to select the right technology? Our scientific account managers can help you choose the most relevant technology.

Fast antibody KD value
Fast turnaround

Get your antibody KD values in 2/3 weeks.

An antibody affinity measurement service adapted to your needs!

Having already developed and characterized 300+ monoclonal antibodies for various customers, ProteoGenix acquired strong expertise in biomolecular interaction analysis. Whether your project requires high throughput KD determination or crude sample analysis (cell, bacteria…), we have everything in hand to bring the most suitable solution to match your requirements.

GE Biacore X100 for antibody binding affinity measurements
SPR / GE Biacore X100 – T200 – 8K
Horiba XelPlex SPRi for antibody cell KD determination
SPRi / Horiba XelPlex
ForteBio OctetRed for KD determination
Octet / ForteBio Octet Red
Application “Gold standard”
High throughput KD determination
Antibody-antigen interaction
Biomolecular interaction analysis
High throughput KD determination
Antibody-cell interaction analysis
Biomolecular interaction analysis
High throughput KD determination
Biomolecular interaction analysis
Technology Surface plasmon resonance (SPR) Surface plasmon resonance imaging (SPRi) Interferometry
Measurement principle Refractive index change Refractive index change Wavelength shift
Label free Yes
Crude sample analysis (cells, bacteria…) No Yes Yes
Possibility to coat proteins (other than antibodies) while maintaining native conformation No Yes No
Imaging No Yes No
Multiplexing ++ ++++ ++
Limit of detection +++ +++ +
Technology complexity + +++ ++
Cost/antibody + +++ ++
Lead time 2/3 weeks

Doubts about the most relevant antibody KD determination technique for your study?

Send your requirements to our PhD account manager.

Case study 1: antibody KD determination between an anti-protein X antibody and X protein expressed at the surface of 293T cells by SPRi technology (Horiba XelPlex)

Aim of the study

We were asked by a customer to measure the anti-protein X antibody binding affinity against a transmembrane protein X expressed at the surface of 293T cells. Expressing and presenting the protein directly in the cell allowed us to present the extracellular epitope while maintaining its native conformation.

Measurements were performed using Surface Plasmon Resonance Imaging technology (Horiba XelPlex).

Biochip functionalization

The biochip was modified using a classical amine coupling strategy. Briefly, a –COOH terminated surface was activated using EDC/NHS leading to a reactive sulfo-NHS ester. This intermediate is known to react with primary amine to form a stable amide linkage.
2 anti-X antibody deposition methods were further tested in order to determine the optimal spotting approach (details provided in the PDF file).

Study of the antibody-cell interaction specificity

X protein cells specific binding was tested by comparing the kinetic curves obtained by injecting X protein cells and control cells (293T cells transfected by an empty plasmide) over an anti-protein X antibody modified biochip.

SPRi antibody cell interaction measurement example

Comparison of X protein cell and control cell injections on the anti-protein X antibody modified biochip led to clear differences in the kinetic curves whatever the conditions of immobilization.

Therefore, the data obtained demonstrates specific binding of X protein cells to anti-protein X antibody.

Kinetic and thermodynamic analysis of the antibody-cell interaction

Kinetic curves were obtained by injecting X protein cells over the anti-X protein antibody modified surface at different concentrations. The deposition method that was chosen is the one that gave best results in the aforementioned study.

Thermodynamic and kinetic antibody cell affinity analysis

Kinetics parameters were determined by fitting the curves at different concentrations using a 1:1 interaction model. Antibody KD value was obtained by calculating the kd/ka ratio.

Kinetic an thermodynamic parameters
ka(M-1.s-1) kd (s-1) KD (M)
Anti-X protein / X protein cells 1.00.1010 2.46.10-4 2.46.10-14


Specific binding of X protein cells to the anti-X protein antibody was demonstrated by SPRi.
SPRi signals allowed the measurement of a low apparent KD which can be interpreted as high affinity antibody-cell interaction. This binding affinity is mainly governed by a high association rate (ka). The multiplexing configuration of SPRi allowed immobilizing the anti-X protein antibody on a same biochip with the two different immobilization methods and at four different concentrations for each immobilization method. During this experiment, 8 different experimental conditions were tested and 282 different sensorgrams were generated in a single biochip.

Click on the button below to get the complete report “Binding study between an anti-X protein antibody and the X protein expressed at the surface of 293T cells by Surface Plasmon Resonance imaging (SPRi) technology”

Case study 2: antibody KD study via Biacore analysis


We were requested by a customer to measure the KD of an antibody/antigen interaction via Biacore. The project dealt with the affinity ranking of 5 different antibodies against a same antigen.


Antigen was immobilized on the dextran coated biochip surface via classical maleimide chemistry leading to stable covalent thioether bonding. Solutions containing the antibodies at various concentrations were then flown over the antigen. Measurement of the SPR signal at different antibody concentrations allowed the determination of the kinetics parameters (on-rate ka, off-rate kd) and thermodynamic parameters (KD).


Antigen Antibody interaction measurement

The antibody/antigen binding affinity can be deduced from the kd/ka ratio leading to the possibility to deduce the affinity ranking.

Antibody ka (1/Ms) kd (1/s) KD (M)
A 4.30×104 2.24×10-4 5.21×10-9
B 1.26×105 9.08×10-4 7.23×10-9
C 6.71×105 3.85×10-4 5.73×10-10
D 2.53×105 4.03×10-4 1.59×10-9
E 2.36×105 7.97×10-4 3.72×10-9

Antibody affinity ranking can be deduced directly from the antibody KD value as the lower the KD value the higher the affinity of the antibody.

Antibody KD ranking: C<D<E<A<B

Antibody affinity ranking: C>D>E>A>B


Biacore analysis led to the conclusion that all 5 antibodies tested demonstrate high affinity against the antigen with C being the best for various reasons:

  • Lower KD indicative of a strong interaction,
  • Favorable kinetic parameters (fast association rate and low dissociation rate).

Click on the button below to get the complete report “Determination of KD of antibody/antigen interaction via Surface Plasmon Resonance (SPR) technology (Biacore X100)”