Binding Assays

Molecular characterization is a critical part of the development of protein-based therapeutics. Sartorius has developed a suite of robust binding assays to provide detailed insights into your product’s biological interactions.

Our cost-effective, ready-to-use, and customizable binding assays contribute to the comprehensive characterization of your product. We apply a range of cutting-edge technologies to ensure we have a platform that suits your needs, including surface plasmon resonance (SPR), enzyme-linked immunoassays (ELISA), electrochemiluminescence (ECL), and mesoscale discovery (MSD). We also offer a full range of Fc characterization assays to assess the potential of your biologic to elicit an immune response.

Sartorius delivers a complete set of product characterization solutions: our binding assays are complemented by our structural and physicochemical assays and cell-based bioassays. Our testing services are fully GCP, GLP, and GMP compliant, facilitating and accelerating biopharmaceutical development.

Fc function expertise

Sartorius provides a range of assays to characterize the Fc region of monoclonal antibodies. For the most common isotypes of therapeutic monoclonal antibodies, we offer pre-developed, pre-qualified assays to analyze Fc binding to FcγR and C1q

These binding assays are supported by our range of bioassays for antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC)

Ready-to-use assays and platforms

Our ready-to-run assays for standard molecule classes save the time and expense of starting from scratch. For more complex assays, our platforms are engineered to provide a springboard for analytical development

Lot release

Full cGMP capability at our global sites, coupled with our expertise in robust assay development, allows us to move your selected assays from characterization to lot release qualification and validation with ease

Single-source characterization

Sartorius offers a complete suite of assays to characterize antibody drugs along the entire development pipeline. This makes it possible to link a protein’s structural and physicochemical properties with its biological function, facilitating decision-making

Find Your Binding Assay

Binding Assay

Fc Binding Characterization

Binding kinetics by SPR  

C1q binding by ELISA and SPR 

ELISA custom assays 

Fc-gamma receptor binding by SPR 

Cell based binding assays 

FcRn binding by SPR 

The Fc domain of antibodies mediates immune functions and may play a role in the mechanism of action of a therapeutic antibody or an ADC therapeutic. Because of this, Fc characterization is required by both the FDA and the EMA guidelines for IND and BLA submissions.

At Sartorius, we have developed assays to streamline Fc characterization.

Ready-to-Use Fc Characterization Assays

Sartorius offers completely developed and pre-qualified assays for the analysis of Fc binding to FcγR and C1q for mAbs. These assays are designed for early-phase testing and are ready to be used for fast, efficient, and economical Fc characterization.

A selection of the assays we offer off-the-shelf are:

  • Binding of IgGs to FcγR by SPR (full panel)
  • Binding of IgGs to FcRn by SPR (human, rat, mouse, or cynomolgus monkey)
  • C1q binding to IgG by SPR
  • C1q binding to lgG by ELISA

Fc Characterization Services

When off-the-shelf solutions aren’t sufficient, the Sartorius team can develop a customized solution that meets the unique requirements of a customer’s product.

C1q Binding Assays

The complement system is part of the immune system that enhances the ability of antibodies and phagocytic cells to clear pathogens and cancerous cells from the body. It consists of small proteins that circulate in the blood, typically as inactive precursors. C1q is a component of the complement system that binds to and activates antigen-antibody complexes.

C1q binding assays measure the activation of the C1-complex using surface plasmon resonance (SPR) and/or ELISA assays.

C1q Assays and Services

Sartorius offers C1q binding assays to support mAb and Fc fusion protein manufacture and process development, as well as characterization and similarity studies. We use C1q binding assays that have been qualified with commercially available therapeutic mAbs to demonstrate performance, and we work closely with our customers to qualify them specifically for your product.  

Our C1q assays include:

  • Highly sensitive C1q binding assays utilizing SPR capable of detecting differences in glycosylation
  • A C1q-binding ELISA assay

Both methods can be used to demonstrate binding or lack thereof for all isotypes of therapeutic mAbs.

Fc-Gamma Receptor Binding Assays

Fc gamma receptors (FcγRs) are members of the IgG super family with an affinity for the Fc region of IgGs. They are expressed on the surface of immune effector cells, where they play a key role in initiating Fc effector functions (e.g., ADCC). The three different FcγR classes have different affinity for IgGs, with binding affected by genetic polymorphisms and Fc glycosylation patterns. During the development of antibody-based therapeutics, the interaction of the Fc region with FcgRs has to be characterized to determine the potential for effector function.

Binding Assay Development for Custom Antibodies

Sartorius performs FcγR binding assays for various IgG antibody isotypes or Fc fusion proteins using SPR. We optimize the performance of FcγR binding assays in collaboration with our customers for their specific antibody therapeutic. To meet all assay needs, we offer a variety of different binding assay formats:

  • FcγR1/CD64
  • FcγR2a/CD32a R variant
  • FcγR2a/CD32a H variant
  • FcγR2b/CD32b
  • FcγR3a/CD16a V variant
  • FcγR3a/CD16a F variant
  • FcγR3b/CD16b

All assays have been qualified with a range of commercially available mAbs.

FcRn Binding Assays

A key factor in the efficacy of therapeutic antibodies is their serum half-life. Optimizing and tracking the interaction between FcRn and IgG throughout antibody drug development is of critical importance.  

Flexible Analytical Services

To track FcRn-IgG binding, Sartorius has developed and qualified ready-to-use FcRn binding assays in a variety of orientations and pH values using SPR as a read-out.

We also offer binding to the most common toxicology species of FcRn to aid decision-making and interpretation of your toxicology study. Cynomolgus monkey, rat, and mouse FcRn binding to human IgGs or fusion proteins can be demonstrated and compared with binding to human FcRn.

Consult Our Experts

Surface Plasmon Resonance (SPR) is a preferred read-out to establish binding kinetics due to its superior sensitivity, minimal sample volume requirements, and ability to measure binding in real-time. SPR is frequently the method of choice for binding assays used during the development of antibody drugs.

Custom Assays for Custom Monoclonal Antibodies

Sartorius has deep expertise in developing and optimizing SPR-based assays of various formats. We work closely with our customers to develop custom assays for all stages of the drug development process, from screening to lot release, providing time-sensitive and cost-effective data on:

  • The strength of the interaction to determine the affinity of the molecule for binding partners
  • The rate of the interaction to define the kinetics of association and dissociation
  • The amount of active material via quantitative measurements of the levels of molecule able to bind
  • The specificity of the molecule by identifying secondary binding partners and assessment of cross-reactivity

SPR assays are developed in fully cGMP certified, state-of-the-art facilities.

Consult Our Experts

Enzyme-Linked Immunoabsorbent Assay (ELISA) is a robust, sensitive, yet highly versatile biomolecular technique used to detect and quantify molecules. As such, ELISA is used at various stages throughout drug development.

Development of Custom ELISA Assays

Sartorius develops custom ELISA assays in close collaboration with our customers to meet their assay specifications. We offer development of the following ELISA formats:

  • Direct ELISA
  • Indirect ELIS
  • Sandwich ELISA
  • Competitive ELISA

Consult Our Experts

For antigens that are difficult to express in a soluble fashion, cell-based binding assays allow measurement of the binding interaction to the native antigen. And because binding assays are a key component of molecule characterization, particularly for antibody-based therapies, Sartorius has developed a variety of methodologies to assess cell-based binding using different technologies, including:

  • Flow Cytometry with iQue Screener PLUS
  • Meso Scale Discovery (MSD) Resources

Cell-Based Assay Development Support

Our expert scientific team can work with you to develop an assay to assess binding to your target of choice using either technology. We can also support assays on the MSD that can be validated to GMP for use in lot release. And our range of assays uses a variety of cell lines to assess binding to common targets, such as CD20, HER2, tmTNFa, as well as methods to assess cell-associated vascular endothelial growth factor (VEGF).

Consult Our Experts

Related Assets

Development of a Platform Live Cell Binding Assay using an iQue®...

PDF 1.6 MB

ELISA - Conception and Applications

Since its conception in the early 1970’s the Enzyme Linked Immunosorbent Assay (ELISA) has been a primary method of analyte detection.

Read Blog Article

Consult Our Experts

Consult Our Experts

Related Content


Biosafety Testing

Learn More

Cell Line Development

Learn More

Cell Banking

Learn More