What is an SPR sensor chip?
The sensor chip is at the heart of Biacore™ systems, providing the physical conditions necessary to generate the SPR signal, attach a variety of molecules to the sensor surface and to study molecular interactions in real time.
The sensor chip surface consists of a glass support on which a gold film has been deposited.
The gold layer is covered with a non-crosslinked carboxylated dextran hydrogel coupled through a linker layer. The dextran matrix increases surface capacity and discourages non-specific binding. The dextran matrix is hydrophilic, and it is flexible so that the attached molecule provides a solution like environment.
The carboxyl groups provide a chemical handle for covalent coupling of biomolecules (i.e. provide functional groups for molecules to bind to).
Sensor Chip CM5 is the most versatile and widely used dextran-based chip, suitable for most SPR applications.
Many sensor chips are pre-functionalized to enable easy attachment of molecules (e.g. NTA coated chips enable capture of His-tagged proteins, Streptavidin and Neutravidin™ sensor chips for biotinylated molecules and Protein A, Protein G, Protein L and PrismA sensor chips for antibody capture).
What are SPR sensor chips used for?
Used with Biacore™ SPR systems, the sensor chips enable detailed characterization of molecular interactions even for challenging targets such as membrane proteins. Biacore™ SPR systems allow you to:
- Understand the relationship between molecular interaction and function
- Screen and characterize for hits and optimize leads based on selectivity, affinity, and kinetics
- Study interactions and define specificity of ions, small molecules, and multidomain proteins or viruses with their targets
- Screen and characterize antibodies and proteins based on yes/no binding, affinity, and kinetics from the fastest on-rates to the slowest off-rates
- Quantitate protein by measuring the concentration of active protein with retained biological function
- Validate results from other techniques/approaches such as ELISA, HTS, or other biophysical methods
What is SPR equipment?
Biacore™ SPR system is a fully integrated system which combines
- Surface plasmon resonance (SPR) detection technology, which monitors interactions on the sensor surface in real-time without labels.
- Sensor chip surfaces – once a sensor chip is docked in a Biacore™ instrument a set of chambers referred to flow cells or channels are formed. This allows multiple molecules to be attached to the sensor surface and the others in solution, are injected using microfluidics and binding is monitored in real-time
- Microfluidics – our microfluidics is a continuous flow system, designed for high quality data with very precise control of sample volumes injected and without diffusion between sample and buffer while in the fluidic channels. This is true for pure samples or complex cell cultures, serum or plasma samples.
What is SPR detection?
During SPR analysis, one of the interacting molecules is attached on a sensor surface, while the potential interacting partner flows over the sensor surface in solution. Interactions between the two are detected in real time through changes in mass concentration close to the sensor surface. Binding data is presented in a sensorgram, where SPR responses in resonance units (RU) are plotted versus time.
Why use Biacore™ SPR sensor chips?
Cytiva has developed a range of tools designed to make Biacore™ assays as easy and reliable as possible, suitable for users of all levels of experience. Sensor chips and the complete toolbox are backed by stringent development, production methods, and quality control. Biacore™ 8 series and Biacore™ systems facilitate compliance with worldwide regulatory expectations by offering Validation Services and 21 CFR Part 11 functionality.
Pre-functionalized sensor chips
What is Sensor Chip NTA?
Poly-histidine is a commonly used tag that can chelate with Ni2+ ions in complex with nitrilotriacetic acid (NTA), providing a convenient approach for capturing his-tagged constructs on Sensor Chip NTA.
Sensor Chip NTA can be used to attach many different types of poly-histidine-tagged proteins for subsequent SPR assays. Interaction of attached proteins with a wide range of analyte molecules can be studied, from low-molecular weight compounds to large proteins. For experiments where low molecular weight analytes are studied, Sensor Chip NTA is the first choice. High affinity antibodies directed against poly-histidine are available in the His Capture Kit as an alternative to nickel chelation on NTA
What is Sensor Chip SA?
Sensor Chip SA provides a sensor surface with covalently attached streptavidin, designed for capture of biotinylated compounds. Capture of biotinylated ligands on a streptavidin surface is a special case of the capturing approach, since the streptavidin-biotin interaction is so tight that the capturing is essentially irreversible. Removal of the ligand in the regeneration step is not usually feasible, and regeneration is normally directed towards removing bound analyte while leaving the biotinylated ligand on the surface.
What is Series S Sensor Chip NA?
Series S Sensor Chip NA is pre-functionalized with NeutrAvidin™ and designed for high-affinity capture of biotinylated molecules with subsequent analysis of ligand-analyte binding in primarily low molecular weight applications. It is an alternative when nonspecific binding effects are experienced with Sensor Chip SA. The sensor chip eliminates the need for preparation of coupling reagents and optimization of coupling conditions.
What are the options for orientation specific capture of antibodies?
There are a couple of pre-functionalized surfaces that capture antibodies based on species, subclass, and chain specificity.
Sensor Chip Protein A has a carboxymethylated dextran matrix with a recombinant Protein A variant covalently attached. The surface ligand is the same as is used for our MabSelect™ SuRe protein purification products. It binds antibodies on the heavy chain within the Fc region from several mammalian species, most notably human antibodies of the subclasses IgG1, IgG2, and IgG4.
Sensor Chip Protein G has a carboxymethylated dextran matrix pre-functionalized with a recombinant Protein G - GammaBind G, Type 2. The recombinant Protein G binds a broad range of IgG, such as human (including subclass IgG3), rat, rabbit, mouse, guinea pig, goat, sheep, and cow.
Sensor Chip Protein L has a carboxymethylated dextran matrix pre-functionalized with a recombinant Protein L for antibodies and antibody fragments containing kappa light chain subtypes (1, 3, and 4) without interfering with its antigen-binding site. Protein L is suitable for the capture of a wider range of antibody classes than both Protein A and Protein G, including IgG, IgM, IgA, IgE, and IgD. Protein L does not bind bovine immunoglobulins, which often contaminate serum supplements, and is therefore especially useful for quantifying antibodies and antibody fragments from serum-based cell cultures.
What is Series S Sensor Chip PrismA?
The sensor chip is pre-functionalized with the same recombinant protein A molecule used to capture antibodies in MabSelect PrismA™ resins for antibody purification.
Sensor Chip PrismA binds a wide variety of antibodies from mammalian species, including human in subclasses IgG1, IgG2, and IgG4. Binding mainly takes place between the constant heavy chain domains, CH2 and CH3, in the Fc region of the antibody. It has enhanced binding affinity – compared to Sensor Chip Protein A – for the VH3 sequence located on the variable heavy chain of the Fab region.