About Us

Nebulabio is a specialized contract research organization (CRO) at the forefront of single-domain antibody discovery and engineering. Our dedicated VHH Phage Display Platform integrates decades of collective experience in camelid immunology, synthetic biology, and high-throughput screening. We have established ourselves as a global leader in nanobody technology, partnering with pharmaceutical, diagnostic, and academic institutions to develop novel biologics against some of the most challenging targets in therapeutic development. Our end-to-end service model—spanning from custom library construction and immunization programs to large-scale screening, affinity maturation, and production—ensures a seamless, efficient path from target concept to developable lead candidate. Our platform is engineered for success, delivering the unique advantages of VHHs: exceptional stability, deep tissue penetration, and access to cryptic epitopes.

☞Principle & Evolution of VHH Phage Display Technology

■ Scientific Origin and Breakthrough

The VHH (Variable domain of Heavy-chain Heavy-chain antibody), or Nanobody®, platform is rooted in a seminal discovery in the late 1980s. Researchers at the Vrije Universiteit Brussel discovered that camelids (camels, llamas, alpacas) naturally produce a unique class of functional antibodies devoid of light chains. These heavy-chain-only antibodies (HCAbs) contain a single variable domain (VHH) that retains full antigen-binding capacity.

The fusion of this discovery with phage display technology created a revolutionary paradigm in antibody discovery. By cloning the repertoires of VHH genes from immunized or naïve camelids into phage display vectors, researchers could generate libraries of these compact, stable binding domains for in vitro selection. This approach bypasses many limitations of traditional antibody systems, offering a direct route to small, robust, and highly specific binders. The profound commercial and therapeutic impact of this technology was globally recognized and has led to the first approved nanobody drug, caplacizumab.

■ Structural Superiority of VHHs

A VHH is a ~15 kDa single-domain protein, approximately one-tenth the size of a conventional IgG. Its advantages stem from its unique structure:

• High Stability: Resistant to extreme temperatures, pH, and chemical denaturants.

• High Solubility: Lacks the hydrophobic interface that can cause scFv aggregation.

• Complex Epitope Access: Its elongated CDR3 loops can penetrate cavities (e.g., enzyme active sites) inaccessible to conventional antibodies.

• Excellent Tissue Penetration: Ideal for imaging and targeting solid tumors.

■ Types of VHH Libraries

Our platform offers expertise in all three strategic library types:

• Immune Libraries: Constructed from camelids hyper-immunized with your target. This yields libraries pre-enriched for high-affinity (nM-pM) binders, offering the fastest route to leads.

• Naïve Libraries: Built from non-immunized camelids, providing universal diversity against any antigen, suitable for novel target discovery or multi-target projects.

• Synthetic Libraries: Designed de novo using humanized frameworks with tailored CDR diversity. This approach delivers fully humanized sequences from the start and allows for library design optimized for specific developability profiles.

☞Core Technology: Construction & Screening Process

Nebulabio’s platform is built upon a proven, two-stage biochemical pipeline, refined through years of optimization.

 Stage I: VHH Phage Library Construction 

• Source Acquisition: For immune libraries, we manage ethical camelid immunization programs. For naïve libraries, we source lymphocytes from healthy animals.

• Gene Amplification: RNA is extracted and reverse transcribed. VHH-specific primers (targeting unique camelid VH gene signatures) are used to amplify the variable domain repertoire.

• Cloning & Transformation: PCR products are cloned into a phagemid vector (e.g., pHEN series) as a fusion with phage protein pIII. The ligation product is electroporated into E. coli to generate a primary bacterial library with >10⁹ individual clones.

• Phage Rescue & QC: Helper phage infection produces the display-ready phage library. Quality Control (QC) includes titering, insert check, and NGS diversity analysis.

 Stage II: VHH Library Screening (Biopanning) 

• Target Presentation: The antigen is immobilized on plates/beads, biotinylated for solution-phase panning, or presented on cells.

• Iterative Selection: The library undergoes 3-5 rounds of binding → washing → elution → amplification. Stringency is increased each round to select for the strongest binders.

• Hit Isolation: Single clones from the final output are screened via monoclonal phage ELISA.

• Lead Characterization: Positive VHH genes are sequenced, expressed solubly, and characterized for affinity (BLI/SPR) and specificity.

Figure1.The VHH genes were amplified from camels hyperimmunized with ASFV proteins and used for the construction of the phage display library. The specific nanobodies were identified using the phage display technique and further used in a sandwich ELISA for detection of ASFV.

☞Nebulabio Integrated Service Workflow

We provide a collaborative, transparent, and milestone-driven service from inception to delivery. Our workflow is designed for maximum efficiency and client involvement.

 Phase 1: Strategic Project Launch 

We begin with a comprehensive consultation to understand your target biology, desired VHH properties (affinity, specificity, cross-reactivity), and final application. Together, we design the optimal strategy: immunization protocol or library selection, panning approach, and characterization cascade.

 Phase 2: Library Generation & Curation 

• Path A - Immune Library: We manage the full immunization and lymphocyte harvest process.

• Path B - Naïve/Synthetic Library: We employ our pre-validated, high-diversity library banks or initiate de novo synthesis.

The constructed library undergoes our stringent 4-point QC before screening commences.

 Phase 3: High-Efficiency Discovery Screening 

Our screening scientists execute the panning campaign, providing regular updates including polyclonal ELISA enrichment data. We employ advanced methods like negative selection and competitive elution to drive specificity.

 Phase 4: Multiplexed Lead Identification & Analysis 

Hundreds of clones are screened in parallel. NGS of the output pool combined with bioinformatic clustering identifies all unique families, ensuring a diverse panel of leads is selected, not just repeated clones.

 Phase 5: Expression, Validation & Prioritization 

Lead VHHs are expressed in E. coli or yeast, purified, and put through a tiered validation cascade:

• Tier 1: Specificity confirmation (ELISA/FACS).

• Tier 2: Affinity ranking (Biolayer Interferometry - Octet).

• Tier 3: Developability assessment (thermal stability by DSF, aggregation propensity).

 Phase 6: Delivery & Knowledge Transfer 

You receive a comprehensive digital project dossier, all physical materials (clones, vectors, purified proteins), and a detailed final presentation reviewing the leads, their characteristics, and recommended next steps.

 Our Service Flowchart: 

☞Applications of the VHH Phage Display Platform

The unique properties of VHHs enable transformative applications across medicine and biotechnology:

• Next-Generation Therapeutics: Developing drugs for oncology (targeting tumor microenvironments), neurology (crossing the blood-brain barrier), and immunology. Their stability allows for inhaled, topical, or oral formulations.

• Cell & Gene Therapy Engineering: Creating VHH-based binding domains for CAR-T cells (improving persistence and function) and other engineered cell therapies.

• In Vivo Diagnostic Imaging: Perfect for PET, SPECT, and optical imaging probes due to rapid blood clearance, high contrast, and deep tumor penetration. FDA-approved examples exist for cardiac imaging.

• Antiviral & Neutralizing Agents: Rapid discovery of VHHs that potently neutralize viruses (e.g., SARS-CoV-2, RSV) by targeting conserved, recessed epitopes.

• Research Reagents & Intrabodies: As ultra-stable, highly specific detection reagents in microscopy, flow cytometry, and Western blot. Their ability to function in the reducing cytoplasm makes them ideal intrabodies for modulating intracellular targets.

• Biosensors & Point-of-Care Diagnostics: Integrating VHHs into diagnostic devices for their robustness and long shelf-life under variable conditions.

Unlock the potential of single-domain antibodies with Nebulabio’s comprehensive VHH Phage Display Platform. Contact our team of experts to initiate a discovery program that leverages the most advanced nanobody technology for your most ambitious targets.