Surface Plasmon Resonance Assay Services
Surface Plasmon Resonance (SPR) is an optical technology that can detect molecular interactions in real time by measuring changes in the refractive index near a sensor surface. This allows for label-free analysis of binding events between biomolecules, providing precise information on affinity determination, binding kinetics, and equilibrium dissociation constants (Kd). SPR is widely used in drug discovery for screening therapeutic candidates, characterizing molecular interactions, and optimizing binding affinities.
SPR can analyze the binding specificity between biomolecules and perform concentration quantification, affinity determination, thermodynamic analyses, and antibody characterization without the need for additional detection reagents, truly reflecting interaction conditions. With its high-throughput, high flexibility, and high sensitivity, SPR has become an important diagnostic method in immunodetection, early drug development, and preclinical drug screening. KACTUS offers experienced surface plasmon resonance services, customized for various experimental protocols to meet the unique needs of your research.
Service Highlights
Various Sample Types
Affinity Determinations
2-5 Day Turnaround
Full Assay Development
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Service Advantages
1. Complex Sample Combinations
Surface plasmon resonance is a versatile tool in that it is suitable for analyzing the interaction and detection of various types of molecules, such as protein and proteins, antigens and antibodies, peptides and proteins, small molecules and proteins, etc. We offer SPR analysis of various sample combinations including:
Antibody / Protein
Protein / Protein
Peptide / Protein
Protein / Small Molecule
2. Flexible Detection Methods
Direct fixation method:
In direct fixation, the ligand is directly fixed on the chip surface through amino coupling. This coupling method involves a reaction with the amino groups of the ligand protein. Generally, amino coupling is used when there are label conflicts with the substances being analyzed.
Capture Method:
The capture method is an indirect coupling method that first fixes capture molecules on a chip, and then leverages the binding affinity between the capture molecules and ligands to couple the ligands on the chip surface. Common capture molecules include Streptavidin (SA), Protein A/L, antibodies, etc. Among them, when using SA as the capture molecule, the ligand protein needs to be in a biotinylated form, utilizing the affinity between SA and biotin to achieve coupling.
3. Technical Expertise
KACTUS' SPR Detection Platform boasts a professional and experienced research team dedicated to the development and optimization of SPR binding assays. With our strict quality control measures for our in-depth product catalog, our team has accumulated a wealth of technical experience on surface plasmon resonance assays, including binding kinetics and binding affinity measurements, providing an important guarantee for the quality of SPR binding assays.
4. Active Collaboration
Our specialized SPR assay service is tailored to meet your specific research needs. Our team of scientists will discuss your specific specifications to develop a personalized experimental setup based on your sample types and data requirements. This collaborative approach ensures that our SPR service aligns with your specifications from start to finish.
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Case Studies
SPR Detection of VLP-Displayed Antigens
To address the challenge of conducting multiple affinity tests on difficult-to-express transmembrane proteins, KACTUS has specially developed biotinylated virus-like particle (VLP)-displayed antigens to meet the experimental requirements of SPR.
Figure 1. Biotinylated Human Claudin 18.2 VLP captured on CM5 Chip via Streptavidin can bind Anti-Claudin 18.2 Antibody with an affinity constant of 1.28 nM as determined in SPR assay.
Figure 2. Biotinylated Human GPRC5D VLP captured on SA Chip can bind Anti-GPRC5D antibody, hFc with an affinity constant of 0.30 nM as determined in SPR assay.
Affinity Detection of Fc Receptor Proteins and Antibodies
Fc receptors are receptor proteins that can bind to the Fc region of antibodies, playing an important role in the screening and efficacy evaluation of antibody drugs. However, this binding interaction is often weak and difficult to effectively assess with conventional detection methods such as ELISA. Therefore, it necessitates the use of methods with higher sensitivity, such as SPR, for detection.
Figure 3. Human Fc gamma RI, His Tag captured on CM5 Chip via anti-his antibody can bind Trastuzumab with an affinity constant of 1.94 nM as determined in SPR assay.
Figure 4. Human FcRn, His Tag captured on CM5 Chip via anti-his antibody can bind Human IgG1 Fc, No Tag with an affinity constant of 0.28 μM as determined in SPR assay.
Affinity Detection of TCR and MHC Peptide Complexes
The detection of the affinity between TCR and MHC peptide complexes is a crucial part of the development of TCR-related drugs, with SPR being a highly effective method for this detection. KACTUS offers SPR detection services to support the development of TCR-related drugs, in addition to our custom expression services for soluble TCRs.
Figure 5. Human HLA-A*02:01&B2M&AFP (FMNKFIYEI) Monomer, His Tag captured on CM5 Chip via Anti-His Antibody can bind HLA-A*02:01&B2M&AFP (FMNKFIYEI) TCR with an affinity constant of 0.923 μM as determined in SPR assay.
Figure 6. Human HLA-A*02:01&B2M&GP100 (YLEPGPVTA) Tetramer, His Tag immobilized on CM5 Chip can bind gp100 TCR&Anti-CD3 bispecific fusion protein with an affinity constant of 0.196 nM as determined in SPR assay.
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Service Workflow & Timeline
Testing Requirements
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Sign Contract
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Develop Method
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Test Sample
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Deliver Data
Standard Sample
Includes standard proteins and antibodies up to 5 sample pairs
2-3 Days
Complex Samples
Includes VLPs, small molecules, or peptides up to 5 sample pairs
3-5 Days
Procedure Compliant with Regulatory Applications
At KACTUS, we are committed to ensuring that our SPR assay development services adhere to the highest standards of regulatory compliance. Our procedures encompass strict supply and management standards for reagents and consumables, meticulous usage records, calibration reports, and regular maintenance for equipment. We prioritize the reliability and integrity of our data through dual backup systems and maintain thorough experimental records in both electronic and paper formats. This rigorous approach guarantees the accuracy and dependability of our SPR analyses, providing you with reliable results for your research and development needs.
Reagents & Consumables:
Strict Supply & Management Standards
Equipment:
Usage Records, Calibration Reports, & Regular Maintenance
Raw Data:
Dual Backup Systems for Enhancedd Reliability
Experimental Records:
Maintained in Both Electronic and Paper Formats
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How SPR Assays Work
SPR technology measures the refractive index change that occurs when molecules bind to or dissociate from a functionalized sensor chip. A ligand is immobilized on the chip surface, while the analyte flows over it in a controlled manner. When binding events occur, the shift in the refractive index is detected in real time, allowing for precise measurement of association and dissociation rates (ka and kd). This enables accurate calculation of the affinity (Kd), which reflects the strength of the interaction.
SPR assays are particularly valuable for studying protein-protein interactions, antibody interactions, small molecule binding, and even weak or transient interactions that are difficult to detect using traditional methods such as ELISA. Because of their sensitivity, SPR-based techniques are widely used in drug discovery to evaluate potential therapeutic candidates and optimize molecular interactions.
