Advanced Single Domain Antibody (SdAb) based Intrabody Discovery Service

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At Creative Biolabs, with over two decades of pioneering experience in antibody engineering, we provide a state-of-the-art Single Domain Antibody (SdAb) based Intrabody Discovery Service. Our platform is meticulously designed to identify and validate high-affinity intrabodies that can precisely target and modulate intracellular proteins in their native environment, offering unprecedented tools for functional genomics, target validation, and innovative therapeutic development.

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Why Single Domain Antibodies (SdAbs): The Superior Scaffold for Intrabodies

While various antibody fragments can be used to create intrabodies, Single Domain Antibodies (SdAbs), also known as VHHs, offer a unique combination of properties that make them the ideal scaffold for intracellular applications. Their superior performance over traditional formats like scFv is a key reason why leading researchers choose SdAbs.

Fig. 1 This figure describe a concept of yeast two-hybrid method. (Creative Biolabs Original). Fig. 1 Schematic representation of yeast two-hybrid method.

Feature	Single Domain Antibody (SdAb)	Conventional Fragments (e.g., scFv)
Size	~15 kDa. Exceptionally small, allowing for superior intracellular diffusion and access to sterically hindered epitopes.	~25-30 kDa. Larger size can limit mobility and target accessibility within crowded cellular compartments.
Stability	High thermal and chemical stability. Robustly folds in the reducing cytoplasmic environment without needing disulfide bonds.	Prone to misfolding and aggregation in the reducing intracellular environment. Often requires complex engineering to improve stability.
Solubility	Excellent solubility. Highly resistant to aggregation, ensuring high functional concentrations within the cell.	Hydrophobic surfaces can lead to aggregation and insolubility, causing cellular toxicity.
Epitope Recognition	Unique elongated CDR3 loop. Can recognize and bind to unique, concave, or cleft-like epitopes (e.g., enzyme active sites) inaccessible to conventional antibodies.	Binding is typically restricted to convex or flat surfaces on the target protein.
Genetic Simplicity	Single genetic construct. Easy to clone and express as a single, stable domain. Ideal for fusion with reporter proteins (e.g., GFP) or functional domains (e.g., ubiquitin ligases).	Requires a linker peptide to connect VH and VL domains, which can be unstable and prone to proteolysis.
Immunogenicity	Low immunogenicity. Especially when using our humanized or camelized frameworks.	Can be immunogenic, and requires significant humanization efforts.

Our Comprehensive Service Portfolio: Tailored to Your Needs

We understand that every research project is unique. Therefore, we offer a flexible, modular service portfolio that allows you to build a discovery plan that perfectly fits your scientific goals and budget.

Platform Selection

Choose the in vivo screening system that best suits your target and cell type.

Yeast Two-Hybrid (Y2H) System: The industry gold standard for high-throughput screening of protein-protein interactions. Ideal for most soluble intracellular targets.
Mammalian Protein-Protein Interaction Trap (MAPPIT): A mammalian cell-based system that allows for screening in a more physiologically relevant context, essential for targets that require specific mammalian post-translational modifications.
Bacterial Two-Hybrid (B2H) System: An alternative platform suitable for certain prokaryotic targets or specific research needs.

SdAb Library Options

Gain access to our world-class, high-diversity libraries.

Immunized Camelid VHH Libraries: Our premier offering. We immunize alpacas or llamas with your target antigen to generate hyper-specific libraries with picomolar to nanomolar affinity potentials. This is the recommended choice for achieving the highest affinity and specificity.
Synthetic Human SdAb Libraries: Large, synthetically constructed libraries based on a stable human framework, offering a rapid, off-the-shelf solution with broad epitope coverage.
Naïve Libraries: Pre-constructed libraries from non-immunized camelids, useful for identifying binders against toxic or non-immunogenic targets.

Validation & Characterization Tiers

From initial hit confirmation to full functional validation, choose the level of characterization you need.

Hit Confirmation Package (Standard): Includes sequencing of positive clones, sequence analysis, and basic binding confirmation via ELISA or Co-Immunoprecipitation (Co-IP) using recombinant proteins.
Advanced Binding Characterization: Provides quantitative affinity and kinetics data through Surface Plasmon Resonance (SPR) or Bio-Layer Interferometry (BLI) analysis.
In-Cell Validation Package: Verifies intrabody performance within the cellular environment through intracellular colocalization (via immunofluorescence with fusion tags like GFP/RFP) and Western Blot analysis to confirm target engagement.
Premium Functional Validation: The most comprehensive package. We design and execute custom cell-based functional assays to demonstrate the intrabody's biological effect, such as enzyme activity inhibition assays, pathway modulation analysis (e.g., phosphorylation status of downstream targets), or cell viability/apoptosis assays.

Downstream Engineering & Production

Intrabody Optimization: Services for affinity maturation and humanization/camelization to enhance performance and reduce potential immunogenicity.
Custom Fusion Constructs: We can fuse your validated intrabody to various functional domains, including fluorescent proteins for live-cell imaging, E3 ligase domains for targeted protein degradation (PROTAC-like molecules), or nuclear/mitochondrial localization signals.
Recombinant Antibody Production: Scalable production of your lead intrabody candidates for further downstream research.

Our Detailed Development Workflow: A Transparent & Phased Approach

Phase 1: Project Initiation & Strategy

Consultation: Our PhD-level scientists work closely with you to understand your research goals.
Target Analysis: We perform in-silico analysis of your target protein to design the optimal "bait" construct.
Strategic Planning: We collaboratively decide on the most suitable library, screening platform, and validation tier for your project.

Phase 2: "Bait" Construction & Library Preparation

Bait Generation: We clone the target antigen into the appropriate "bait" vector.
Quality Control: We rigorously test the bait for proper expression and ensure it does not self-activate the reporter genes, which is critical for preventing false positives.
Library Preparation: We prepare our high-quality SdAb "prey" library for screening.

Phase 3: High-Throughput In Vivo Screening

Screening: The bait and prey constructs are introduced into host cells (e.g., yeast). We screen up to 10⁸-10⁹ individual clones to ensure comprehensive coverage of the library.
Selection: Only cells containing an interacting bait-prey pair can survive and grow on highly selective nutrient-deficient media.

Phase 4: Hit Confirmation and Identification

Hit Picking: Positive colonies are isolated for further analysis.
Validation: We confirm the interaction to eliminate potential false positives.
Sequencing & Analysis: The DNA encoding the positive SdAb "hits" is sequenced and clustered into families based on sequence similarity.

Phase 5: In-depth Validation & Characterization

Based on your selected service tier, we perform a suite of assays to characterize the binding affinity, specificity, and biological function of the lead candidates.

Phase 6: Final Deliverables

You will receive a comprehensive report detailing all methods, data, and results, along with the specified material deliverables (sequences, plasmids, purified protein).

Why Choose Creative Biolabs?

Unmatched Expertise: Over 20 years of leadership in antibody engineering and therapeutic discovery.

World-Class Libraries: Access to our proprietary, high-diversity single domain antibody libraries from immunized camelids (alpaca, llama) or our advanced synthetic and naïve human libraries.
Proven Technology: Our optimized Y2H and M2H screening platforms maximize the probability of identifying high-affinity, functional intrabodies.
Comprehensive Downstream Services: We offer a full suite of validation services, including affinity measurement (SPR/BLI), epitope mapping, and diverse functional assays.
Customized Solutions: We collaborate closely with you to design a project that perfectly aligns with your specific targets and research objectives.
Transparent Process: We provide regular updates and a comprehensive final report detailing all data and methodologies.

Related Featured SdAb Discovery Services

Creative Biolabs offers a complete, end-to-end solution for single domain antibody development. Explore our related services to seamlessly advance your project from discovery to application.

Contact our team of experts to discuss your project. Let us help you unlock the potential of intracellular targets with our cutting-edge SdAb-based intrabody discovery platform.

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Frequently Asked Questions (FAQ)

Q: What is the main advantage of an SdAb intrabody over an scFv intrabody?

A: The primary advantages are superior stability and solubility. SdAbs are single, robust domains that fold correctly in the reducing intracellular environment, whereas scFvs often misfold and aggregate, leading to non-functionality and toxicity.

Q: What starting material do I need to provide?

A: Typically, you will need to provide the target protein sequence or a plasmid encoding the target antigen. Our scientific team will work with you to determine the exact requirements based on your project.

Q: Can you target a specific post-translational modification (PTM)?

A: Yes. Our systems are capable of identifying intrabodies that recognize specific PTMs, such as phosphorylation or ubiquitination, allowing for the study of PTM-dependent protein functions.

Q: What is the typical timeline for an intrabody discovery project?

A: While timelines vary based on project complexity, a standard project from library screening to delivery of validated hits can typically be completed within 12-18 weeks, depending on the validation tier selected.

Reference

Moutel, Sandrine, et al. "NaLi-H1: A universal synthetic library of humanized single domain antibodies providing highly functional antibodies and intrabodies." Elife 5 (2016): e16228. https://doi.org/10.7554/eLife.16228

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