High-Throughput, Label-Free Interaction Screening — Monitor Hundreds of Binding Events Simultaneously on a Single Biochip
Creative Proteomics offers surface plasmon resonance imaging (SPRi) services for multiplexed, real-time biomolecular interaction analysis. Unlike conventional SPR which measures one interaction at a time, SPRi uses an imaging detector to monitor hundreds of arrayed sensing spots simultaneously — delivering kinetic rate constants, affinity values, and epitope specificity data at a throughput impossible with channel-based instruments.
What SPRi Enables:
One chip. Hundreds of interactions. Real-time kinetics. No labels.
Surface plasmon resonance imaging (SPRi) is a label-free optical biosensing technique that combines the detection principle of conventional SPR with the spatial multiplexing of a microarray. Instead of measuring reflectivity at a single sensing spot with a photodetector, SPRi uses a CCD camera to image the entire sensor surface simultaneously. Each region of the biochip can be functionalized with a different capture molecule — a protein, antibody, peptide, DNA probe, or small molecule — enabling hundreds of independent binding experiments in parallel, all under identical buffer and temperature conditions.
The throughput difference is transformative: a conventional 4-channel SPR system screens ~3 interactions per run. An SPRi biochip with 96 spots can screen 96 interactions simultaneously. What takes weeks on a channel-based instrument takes hours on SPRi — without sacrificing the real-time kinetic data (ka, kd, KD) that makes SPR the gold standard for interaction analysis.
| Parameter | SPR Imaging (SPRi) | Conventional SPR |
| Detection | CCD camera imaging entire biochip surface | Photodetector at a single sensing spot |
| Format | Microarray — hundreds of spots per chip | Flow cells — 1–8 channels per run |
| Throughput | Up to 1,000+ interactions per run | ~3 interactions per 4-channel run |
| Ligand Immobilization | Ex situ spotting — flexible array design | In situ microfluidic injection |
| Sample Consumption | ~80 nL per interaction spot | ~30 µL per injection per channel |
| Best For | High-throughput screening, epitope binning, parallel kinetic profiling | Deep kinetic characterization of a few purified interactions |
SPRi is not a replacement for conventional SPR — it is a complementary high-throughput front end. Use SPRi to screen hundreds of candidates in hours and identify the most promising ones; then use conventional SPR for the deepest kinetic characterization of your top hits.
If your project involves screening or comparing more than a handful of interactions, SPRi delivers answers at a scale that conventional SPR simply cannot match.
100× Throughput Over Conventional SPR
A single 96-spot SPRi biochip replaces ~30 conventional SPR runs. For antibody screening, epitope binning, or fragment library profiling, SPRi compresses weeks of instrument time into a single day — with full kinetic data (ka, kd, KD) for every interaction, not just yes/no binding calls.
Identical Conditions Across All Interactions
Every spot on an SPRi chip is exposed to the same analyte solution, at the same concentration, temperature, and flow rate, at the same moment. This eliminates the run-to-run variability that complicates cross-comparison in sequential SPR experiments — critical for reliable epitope binning and affinity ranking.
Minimal Sample Per Data Point
Each interaction consumes ~80 nL of spotted ligand and requires a single analyte injection for the entire chip. For precious protein samples, fragment libraries, or limited patient sera, SPRi extracts the maximum information from the minimum material.
Custom Array Design — You Define the Experiment
Our scientists work with you to design the spotting layout: which ligands, at what concentrations, with which controls and reference spots. Whether you need a focused 16-spot panel for lead comparison or a 400-spot array for comprehensive epitope binning, the chip is built around your question.
SPRi is a high-throughput platform that scales from targeted screening to comprehensive interaction profiling. Each service below leverages the technique's unique array-based multiplexing to answer questions at a throughput impossible with channel-based instruments.
Array Design & Biochip Preparation
Ligands (proteins, antibodies, peptides, DNA, or small molecules) are selected and the spotting layout is designed collaboratively. Ligands are printed onto a gold-coated SPRi biochip using a robotic array spotter. Each spot (~100–300 µm diameter) is functionalized with a different capture molecule. Reference spots and positive/negative controls are included in the layout.
Biochip Assembly & Instrument Setup
The printed biochip is mounted in the SPRi instrument. Running buffer is flowed across the surface. The working angle is selected on the SPR reflectance curve for optimal sensitivity. The CCD camera is focused and calibrated.
Analyte Injection & Real-Time Imaging
Analyte solution is injected and flows across the entire biochip surface. The CCD camera captures the SPR signal from every spot simultaneously in real time. Association is monitored during injection; dissociation is monitored during buffer wash. A single injection provides kinetic data for all spots on the chip.
Data Extraction & Kinetic Fitting
Sensorgrams (binding response vs. time) are extracted for each spot. Reference spot signals are subtracted. Association and dissociation phases are fitted to 1:1 binding models (or more complex models as appropriate) to extract ka, kd, and KD for each interaction.
Cross-Comparison & Epitope Analysis
For epitope binning, pairwise competition matrices are constructed. Antibodies are clustered into epitope families based on cross-blocking patterns. For screening projects, hits are rank-ordered by affinity, off-rate, or other user-defined criteria.
Report Delivery
You receive annotated sensorgrams for every interaction, kinetic parameter tables (ka, kd, KD) with fitting confidence metrics, epitope binning dendrograms or network maps (when applicable), and a written interpretation highlighting key findings and recommended next steps.
High-Throughput SPR Imaging Platform
– CCD-based imaging detection for real-time monitoring of all array spots simultaneously
– Gold-coated biochip with up to 400+ discrete sensing spots per chip
– Automated microfluidic flow cell for controlled analyte delivery
– Robotic array spotter for precise, reproducible ligand deposition
– Compatible with proteins, antibodies, peptides, DNA, and small molecules
The SPRi platform bridges throughput and data quality: it delivers the same real-time kinetic parameters (ka, kd, KD) as conventional SPR, but for hundreds of interactions in parallel on a single biochip. For the deepest kinetic characterization of individual high-value interactions, our conventional SPR service provides the highest sensitivity and the most refined kinetic models.
| Parameter | Recommended Specifications |
| Ligands (for spotting) | Purified proteins, antibodies, peptides, or DNA probes; 10–100 µg/mL in spotting buffer; ~5–20 µL per ligand for the full array |
| Analytes (for injection) | Proteins, antibodies, small molecules, peptides, crude supernatants, or serum; 50–200 µL per injection at 1–100 nM (proteins) or 1–100 µM (small molecules) |
| Concentration Series | 5–8 concentrations recommended for full kinetic analysis; 3–5 for screening/ranking |
| Running Buffer | PBS, HBS-EP, or Tris-based buffers preferred; avoid high concentrations of organic solvents (>5% DMSO) that may affect the gold surface |
| Shipping | Ship on dry ice or ice packs. Include complete buffer composition, expected molecular weight, and target concentration range |
SPRi is compatible with crude samples including hybridoma supernatants and serum. Contact us during the array design phase to discuss your sample types and we will optimize spotting density, blocking strategy, and reference spot placement accordingly.
Each technique measures binding, but they answer different questions at different scales. The table below helps you choose the right tool for your stage of discovery.
| Feature | SPR Imaging (SPRi) | Conventional SPR | BLI | ITC |
| Throughput | High — 100s per chip | Low — 1–8 per run | Medium — 8–16 per run | Very low — 1 per hour |
| Kinetics (ka, kd) | Yes — real-time, all spots simultaneously | Yes — gold standard | Yes — real-time | No |
| Thermodynamics (ΔH, ΔS) | No | No | No | Yes — primary method |
| Immobilization | Ex situ spotting (flexible array) | In-channel microfluidic injection | Biosensor dip-and-read | None — in solution |
| Epitope Binning | Excellent — pairwise on one chip | Possible but sequential, slow | Possible, medium throughput | No |
| Sample per Data Point | ~80 nL spotted ligand | ~30 µL analyte per channel | ~200 µL per well | 300 µL at 5–50 µM |
| Best Used For | High-throughput screening, epitope binning, parallel kinetic profiling | Deep kinetic characterization of purified interactions | Medium-throughput screening, crude sample compatibility | Mechanism of binding, full thermodynamic profile |
SPRi excels at multiplexed screening, but it is not optimized for every binding question:
| If Your Question Is... | Why SPRi Is Not Ideal | Use Instead |
| I need the highest-sensitivity kinetic data for a single purified interaction. | SPRi measures at a single working angle with slightly lower refractive index resolution than scanning-angle SPR | Conventional SPR for the deepest kinetic characterization |
| I only have 1–3 interactions to characterize. | SPRi's throughput advantage is wasted on small numbers; chip preparation overhead exceeds the benefit | SPR or BLI for rapid low-count analysis |
| I need thermodynamic parameters (ΔH, ΔS, ΔG). | SPRi does not measure heat; it is a binding detection technique | ITC for complete thermodynamic characterization |
The ideal workflow: screen by SPRi to identify top candidates and classify epitope families → validate the best hits by conventional SPR for refined kinetics → characterize binding mechanism by ITC if thermodynamics are needed. Contact our team to design a multi-stage interaction analysis strategy.
From Sensorgrams to Epitope Networks — Complete Interaction Data at Scale
Each SPRi project delivers a comprehensive, publication-ready data package covering every interaction on the chip.
Annotated Sensorgrams with Kinetic Fits
Overlaid binding curves for all spots on the chip, with fitted kinetic parameters (ka, kd, KD) for each interaction. Concentration-dependent sensorgram families with 1:1 binding model fits for quantitative analysis.
Epitope Binning & Interaction Network Maps
Dendrogram or network visualization of epitope families from pairwise competition data. Competition matrix heat maps show blocking vs. non-blocking antibody pairs at a glance.
How is SPRi different from the conventional SPR service you also offer?
Conventional SPR measures one interaction at a time in a microfluidic flow cell and provides the highest sensitivity for deep kinetic characterization of purified interactions. SPRi uses an imaging detector and an arrayed biochip to monitor hundreds of interactions simultaneously, trading a slight reduction in single-point sensitivity for massive throughput gains. The two platforms are complementary: use SPRi for screening and epitope binning, conventional SPR for refined kinetics on top hits.
How many interactions can SPRi monitor in a single experiment?
Our SPRi biochip accommodates up to 400+ discrete sensing spots. A typical experiment might monitor 96–200 interactions plus reference and control spots. The total data output depends on the array design: for epitope binning, a 16-antibody panel generates 256 pairwise competition measurements in one unattended run. Each spot produces a full sensorgram with ka, kd, and KD.
Can I use crude samples like hybridoma supernatants with SPRi?
Yes. SPRi flow cells are designed with larger channel dimensions than conventional SPR microfluidics, making them more tolerant of crude samples. Hybridoma supernatants, bacterial lysates, and serum can be analyzed directly, though sample complexity may increase non-specific background. We optimize blocking conditions and reference spot design to account for complex matrices.
What types of ligands can be immobilized on an SPRi chip?
Proteins, antibodies, peptides, DNA/RNA probes, carbohydrates, and small molecules can all be immobilized on SPRi biochips. The gold surface is functionalized with a self-assembled monolayer (SAM) chemistry that allows covalent attachment through amine, thiol, or streptavidin-biotin coupling. Our team helps select the optimal surface chemistry based on your ligand chemistry and the required spot density.
How do epitope binning results from SPRi compare to conventional SPR binning?
SPRi epitope binning achieves finer discrimination than sequential SPR binning because all pairwise competitions are measured simultaneously under identical conditions. Run-to-run variability — which can blur epitope boundaries in sequential SPR — is eliminated. Studies using the IBIS-MX96 SPRi platform have demonstrated that larger antibody panels analyzed in parallel yield higher epitope discrimination resolution than smaller panels analyzed sequentially.
Can SPRi measure small molecule binding?
Yes. SPRi detects small molecule binding (typically >200 Da with good signal-to-noise). The array format is particularly advantageous for fragment screening, where dozens to hundreds of fragments need to be tested against one or more targets. Each analyte injection provides binding data for all spots simultaneously, enabling rapid hit identification and affinity ranking. For sub-200 Da fragments or very weak binders, conventional SPR may provide higher sensitivity.
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