Custom VHH-conjugated LNP development services for cell-selective delivery of mRNA, siRNA, and gene-editing payloads, covering VHH format engineering, site-specific conjugation, ligand density optimization, functional ligand quantification, and targeting validation in relevant cell models.
VHH-conjugated lipid nanoparticles (VHH-LNPs) are lipid nanoparticles that display single-domain antibodies, also called VHHs or single-domain antibodies (VHHs), on their surface. A VHH is the antigen-binding variable domain of a camelid heavy-chain-only antibody. It weighs about 12–15 kDa, roughly one tenth of a full IgG, and it carries no Fc region. On an LNP surface, that difference matters: a smaller ligand adds less steric bulk, keeps the particle closer to its original size and biodistribution behavior, and avoids the Fc-driven uptake by phagocytes that often defeats full-antibody targeting.
Conventional LNPs, after in vivo dosing, tend to accumulate in the liver. Changing the lipid composition can shift this tropism, but passive approaches of that kind need extensive screening and rarely reach a defined cell type. Attaching a VHH converts that passive carrier into an active one: the particle gains a binding domain with antibody-class affinity and specificity, plus a single defined attachment point that allows the ligand to be placed facing outward, toward the receptor, instead of at a random angle.
We help pharmaceutical and biotechnology teams build VHH-conjugated LNPs for mRNA, siRNA, circular RNA, guide RNA/mRNA combinations, proteins, peptides, small molecules, and imaging payloads. Our work spans VHH format and attachment tag design, VHH-lipid conjugate synthesis, conjugation route selection, ligand density screening, free VHH removal, functional ligand quantification, and target-cell validation.
VHH-Functionalized LNP Structure Illustration
Our modular services address the full VHH-LNP workflow, from the choice of binding domain to confirmation that the encapsulated payload performs in the intended cell population.
We define a VHH targeting strategy around antigen expression, receptor accessibility, internalization behavior, and payload requirements.
We prepare VHH-compatible lipid conjugates and select reactions that help preserve the antigen-binding surface.
We integrate VHH conjugates into a suitable LNP backbone while balancing receptor exposure against colloidal stability.
We examine both the LNP carrier and the biological activity of the surface-bound VHH, which cannot be established by total protein loading alone.
We distinguish true receptor-directed delivery from nonspecific cell association and from uptake without productive cargo release.
We refine preparation and surface-coupling variables so that selected VHH-LNP candidates can be reproduced and meaningfully compared.
The right architecture depends on how much antigen sits on the target cell and what that receptor does when it is cross-linked. BOC Sciences supports four display architectures, and we help clients choose between them based on antigen density, receptor turnover, and the internalization behavior of the target.
One VHH, one attachment point, minimal footprint on the particle. This is the configuration we start from when the antigen is abundant and the receptor internalizes readily.
Two or more copies of the same VHH, either as a tandem genetic construct or as separate ligands spaced across the surface. Avidity rises without switching the target.
Two different VHHs on one particle. This lets the LNP require two features at once before it commits to uptake, which sharpens selectivity in mixed cell populations.
A VHH paired with a second ligand class on the same surface. The two ligands do different jobs: one for recognition, one for transport or for crossing a barrier.
Choosing the attachment chemistry is essential for preserving antigen recognition. The methods below differ in site selectivity, required VHH engineering, reaction conditions, and whether the VHH is coupled before or after LNP assembly.
Sortase recognizes a C-terminal peptide motif on an engineered VHH and installs a functionalized peptide handle, such as an azide-bearing oligoglycine.
A selected noncanonical amino acid containing a bioorthogonal handle can be incorporated into an engineered VHH at a defined site.
Copper-free bioorthogonal reactions can join suitably functionalized VHHs to PEG-lipids or reactive groups displayed on LNPs.
An accessible engineered cysteine supplies a thiol group for reaction with maleimide-functionalized PEG-lipids or LNP surfaces.
NHS ester chemistry couples activated carboxyl-derived groups to accessible VHH amino groups, typically lysine side chains or the N-terminus.
Purified VHH-PEG-lipid conjugates can be introduced into preformed LNPs under controlled mixing and incubation conditions.
Share your target, payload, and delivery goals with us. BOC Sciences can help you design and evaluate suitable VHH targeting architectures and conjugation strategies tailored to your project requirements.
Conventional LNPs rely largely on passive distribution and biological interactions. VHH conjugation adds receptor-directed targeting, offering potential advantages in specificity, cellular uptake, and design flexibility.
VHHs provide receptor-specific recognition absent from conventional LNPs. In reported CD8-targeted systems, reporter expression reached 58.7% of CD8+ T cells, versus 0.6–3.5% in several non-target populations. Switching to a CD4-binding VHH redirected expression toward CD4+ cells, demonstrating ligand-dependent targeting specificity.
VHH binding can promote receptor-mediated internalization, enabling separate evaluation of receptor binding, uptake, and endosomal escape. Reported CD8-targeted VHH-LNPs produced approximately 6.9-fold higher splenic reporter signal than matched ligand-free LNPs, with expression enriched in targeted cells.
VHHs (12–15 kDa) are substantially smaller than full IgG antibodies (~150 kDa) and lack Fc regions, reducing steric bulk on LNP surfaces. Reported VHH-LNP formulations maintained particle sizes near 76 nm, PDI below 0.05, and encapsulation efficiency above 96%.
Changing VHH ligands can redirect an LNP platform toward different receptors without redesigning its core formulation. Monovalent, multivalent, and bispecific VHH formats offer flexible targeting, while site-specific conjugation enables controlled ligand orientation and density for comparative screening.
BOC Sciences develops VHH-conjugated LNPs across the payload classes used in targeted delivery research. Each payload changes what the conjugation has to protect: RNA payloads need the encapsulation environment left intact, while protein and peptide payloads need mild conditions and aggregation control. We match the surface chemistry to the payload rather than forcing one onto the other.
| Payload Type | Supported Uses & VHH-LNP Development Considerations | Request Information |
|---|---|---|
| VHH-LNP Development for siRNA | Used for cell-selective gene silencing in defined cell subsets. Development covers siRNA encapsulation, free RNA reduction, ligand density matching, and knockdown comparison against non-targeted LNPs. Our lipid nanoparticles for siRNA delivery work provides the base formulations used here. | Inquiry |
| VHH-LNP Development for mRNA and Reporter RNA | Used for reporter expression, encoded-protein expression, and antigen delivery studies. Development covers mRNA integrity, encapsulation efficiency, ligand density, particle stability, and expression readouts in antigen-positive versus antigen-low cell models. Base systems come from our lipid nanoparticles for mRNA delivery service. | Inquiry |
| VHH-LNP Development for circRNA and Self-Amplifying RNA | Used where longer or sustained expression is needed from a single delivery event. Development covers payload protection, post-conjugation size control, stability evaluation, and cell-based expression comparison. Supported through our lipid nanoparticles for circRNA delivery capability. | Inquiry |
| VHH-LNP Development for gRNA/mRNA Combination | Used for cell-restricted genome editing studies. Development covers co-encapsulation ratio control, particle uniformity after conjugation, and editing readouts in target versus non-target cells. Supported by our lipid nanoparticles for CRISPR RNP delivery experience. | Inquiry |
| VHH-LNP Development for Protein and Peptide | Used for antigens, enzymes, and functional protein payloads. Development covers mild loading conditions, aggregation control, activity retention after conjugation, and VHH-dependent uptake evaluation. Base work builds on our LNP-based protein delivery service. | Inquiry |
| VHH-LNP Development for Small Molecule | Used for hydrophobic, amphiphilic, or ionizable small molecules directed to specific cells. Development covers drug-lipid compatibility, loading route, leakage control, particle stability after surface modification, and release behavior. | Inquiry |
| VHH-LNP Development for Fluorescent and Imaging | Used to track uptake, intracellular localization, and distribution trends. Development covers labeled RNA, labeled protein, and dye payloads, with matched non-targeted imaging LNPs prepared as controls. | Inquiry |
| VHH-LNP Development for Custom Payload | Used for unusual payloads, multi-payload systems, or early feasibility studies. Development covers payload compatibility assessment, loading sequence, conjugation route selection, particle stability, and target-cell delivery performance. | Inquiry |
VHH-LNP programs usually stall in one of six places. Each has a different cause, and each needs a different measurement to confirm the fix worked. BOC Sciences diagnoses first, then changes one variable at a time.
Conjugation can damage a VHH before it ever reaches a cell. We control reaction pH, organic solvent content, reagent excess, and reaction time, then measure retained affinity by surface plasmon resonance or biolayer interferometry against the unconjugated VHH. Antigen-probe binding on the finished particle tells us the fraction that survived, not the fraction that was added.
Hydrophobic handles placed directly on the particle are a common cause. Reported work shows direct DBCO-mediated conjugation on LNPs can double particle size, widen PDI, and produce micellar aggregates and multilamellar structures. We compare routes such as TCO-based two-step ligation or post-insertion of a pre-formed conjugate, and select by size, PDI, and morphology.
Random coupling can point the binding face toward the lipid surface. We use C-terminal site-specific attachment through sortase ligation, an engineered cysteine, or a noncanonical amino acid, then tune the peptide linker and PEG spacer length so the paratope clears the PEG brush layer rather than sitting inside it.
More ligand is not better. Reported CD8-targeted VHH-LNP data follow a bell-shaped curve with an optimum near 0.1 VHH per 100 nm2, and delivery collapses above it as receptors are internalized and degraded. We build a density ladder, typically 0.01 to 0.5 mol% of conjugated lipid, and let uptake and functional readouts pick the setting.
Particles can enter the cell and still deliver nothing. When in vitro uptake looks strong but the readout stays flat, we separate the steps: surface binding, internalization, payload release, and function, using LNP endosomal escape evaluation, intracellular localization analysis, payload integrity checks, and the relevant functional readout. The failing step becomes the target of the next round.
When results drift between preparations, the cause is usually process, not chemistry. We trace it through conjugation conversion, free VHH removal efficiency, insertion conditions, and batch comparability data. Where functional readouts vary between batches, our LNP transfection troubleshooting services help locate the variable responsible.
BOC Sciences helps research teams troubleshoot VHH activity loss, conjugation-induced aggregation, ligand density imbalance, free VHH removal, and payload function readouts.
We begin with the target antigen, its expression pattern across the cell types you care about, the payload, and the readout you intend to use. We also review what has already been tried and what failed, because a previous failure usually narrows the design space. The output of this step is a written development plan with a defined candidate set, control set, and decision criteria.
We choose the VHH format, the attachment site, the conjugation chemistry, and the PEG spacer. The choice depends on what sequence or construct you have, how the antigen behaves on the cell, and which lipid system the payload requires. This step connects to our lipid nanoparticles synthesis capability, so the conjugation route and the particle are designed as one system.
We prepare the density ladder and the control panel: non-conjugated LNPs, non-binding VHH-LNPs, and competitors where the study calls for them. During preparation we adjust lipid composition, payload loading, mixing conditions, conjugation conversion, free VHH removal, and buffer exchange, and we record the parameters for each candidate so the selected one can be repeated.
Each candidate is characterized for size, PDI, zeta potential, encapsulation, conjugation efficiency, and functional ligand density. We then run uptake and functional readouts across the matched cell panel, and report where the optimum sits and why. The final package includes the parameter set, the batch comparison data, and a recommendation for the next step.
VHH-conjugated LNPs are used wherever a payload needs to reach a defined cell population instead of whatever the carrier happens to encounter. BOC Sciences supports development for the four application areas below, each with its own target biology and its own set of controls.
Challenge: A research team needed selective reporter mRNA delivery to CD8+ T cells. Their antibody-LNP averaged 165 nm (PDI 0.28), with 82% encapsulation and only 1.4-fold target selectivity. They needed better conjugation and controlled ligand density.
Diagnosis: Random IgG coupling compromised ligand orientation, while Fc-associated uptake reduced selectivity. Unoptimized ligand density and residual free antibody further interfered with CD8-specific targeting.
Solution: We replaced IgG with an anti-CD8 VHH carrying a C-terminal LPETG motif and compared two attachment routes. The first used sortase-mediated cysteine installation followed by maleimide-PEG-lipid coupling. The second used a C-terminal azide handle with a two-step TCO-tetrazine ligation strategy. We screened five ligand densities (0.008–0.5 mol%), purified candidates by size-exclusion chromatography, and quantified functional surface VHH using recombinant CD8 probes. Controls included non-conjugated LNPs, non-binding VHH-LNPs, and free VHH competition. Particle properties and CD8+ cell expression guided selection. We also support nanoparticle in vivo distribution analysis when tissue-level evaluation is needed.
Result: Optimal density was approximately 0.1 VHH per 100 nm2 (18–20 ligands/particle). Selected LNPs averaged 78 nm (PDI 0.06), with over 95% encapsulation. Reporter expression reached 58% in CD8+ cells versus 0.6–3.5% in non-target populations, with 6.9-fold higher targeted signal than unmodified LNPs. Three batches demonstrated consistent performance.
Challenge: Direct DBCO-azide conjugation increased VHH-LNP size from 108 to 210–230 nm (PDI 0.35). Antigen binding was nearly undetectable, and reporter expression matched non-targeted LNPs. The team needed a gentler conjugation strategy.
Diagnosis: Hydrophobic DBCO groups promoted particle aggregation. Unoptimized VHH-to-PEG-lipid ratios and VHH multimer formation further compromised effective ligand presentation.
Solution: BOC Sciences compared three strategies: direct DBCO-azide conjugation, pre-conjugation of VHH to DSPE-PEG2000 followed by post-insertion into LNPs, and TCO-tetrazine surface coupling. For post-insertion, we screened sortase A concentrations of 1 and 5 μM and VHH-to-PEG-lipid ratios of 1:1, 1:3, and 1:10. Gel electrophoresis monitored conjugation conversion and multimer formation, while buffer exchange removed uninserted conjugates. Candidates were evaluated for size, PDI, zeta potential, morphology, encapsulation, antigen binding, cellular uptake, and reporter expression in antigen-positive and antigen-low models, supported by our nanoparticle in vitro evaluation capability.
Result: Post-insertion using 1 μM sortase A and a 1:3 ratio minimized multimer formation. Selected LNPs measured 132 nm (PDI 0.12), retained over 90% encapsulation, and remained stable for seven days at 4 °C. Antigen-positive uptake increased 3.4-fold and reporter expression 4-fold, while antigen-low uptake increased less than 1.3-fold. The client selected the post-insertion strategy.
Advanced LNP Design and Synthesis Technologies
BOC Sciences runs VHH conjugation and LNP assembly as one connected process. We support sortase-mediated ligation, noncanonical amino acid handles, TCO-tetrazine two-step ligation, engineered cysteine coupling, and post-insertion routes, and we select between them by data rather than by habit. Each candidate is prepared with its parameters recorded, so the selected one can be made again.
Extensive Inventory of Ready-to-Use Lipid Materials
We keep ionizable lipids, helper lipids, cholesterol, and functionalized PEG-lipids in stock, including maleimide-, DBCO-, TCO-, azide-, and NHS-terminated PEG-lipid anchors. Having the reactive lipid available in several spacer lengths means route and spacer screening can start without waiting on a custom synthesis step.
Rapid Response and Technical Consultation
Most VHH-LNP projects arrive with a specific failure already in hand. We review the target biology, the payload constraints, and what has been tried, then return a development plan with a candidate set, a control set, and decision criteria. Questions go to the scientists who will run the work, not to a general inbox.
Comprehensive LNP Characterization Platform
We measure particle size, PDI, zeta potential, morphology, encapsulation, conjugation efficiency, free ligand, and functional ligand number in one place. Counting ligands that still bind their antigen is what separates a usable candidate from one that only looks decorated. This platform underpins our LNP critical quality attributes & QC testing service.
Detailed Process Documentation and Technical Reports
Every project closes with a report that lists the parameter set, the analytical data, the control results, and the reasoning behind each selection. Batch comparison data are included where repeat preparations were made. The aim is that you can continue the work from our documents without repeating the screening.
Conventional lipid nanoparticles rely largely on their lipid composition, particle properties, and interactions with biological environments to determine cellular uptake and distribution. VHH-conjugated LNPs introduce single-domain antibody fragments onto the particle surface to enable recognition of selected cell-surface receptors or antigens. Compared with full-length IgG antibodies, VHHs offer a smaller molecular size of approximately 12–15 kDa and flexible options for site-specific modification. These properties support controlled ligand presentation and customizable targeting designs. VHH-LNPs can be developed for mRNA, siRNA, and other payloads, although improved cell selectivity and functional delivery must be confirmed experimentally for each target and formulation.
The most suitable conjugation method depends on VHH structure, available functional groups, lipid anchors, and formulation compatibility. Common approaches include sortase-mediated C-terminal functionalization, engineered cysteine-maleimide coupling, noncanonical amino acid incorporation, and SPAAC or IEDDA click chemistry. Site-specific conjugation generally offers better control over ligand orientation than random amine coupling, reducing the risk of modifying antigen-binding regions. Another option involves preparing VHH-PEG-lipid conjugates before inserting them into preformed LNPs, potentially reducing particle aggregation during surface modification. Method selection should consider conjugation efficiency, VHH structural integrity, surface accessibility, and retained receptor-binding activity rather than relying on chemical conversion alone.
Sortase-mediated C-terminal functionalization enables site-specific attachment of VHHs to lipid nanoparticles while minimizing interference with their antigen-binding regions. The process begins by engineering a VHH with a C-terminal LPETG recognition sequence. Sortase A then catalyzes the attachment of a functionalized oligoglycine peptide, introducing a reactive handle such as an azide group. The modified VHH is subsequently conjugated to a functionalized PEG-lipid, such as DSPE-PEG-DBCO, through copper-free click chemistry. The resulting VHH-PEG-lipid conjugate can be incorporated into preformed LNPs through post-insertion. Finally, the modified nanoparticles are purified and evaluated for particle size, ligand density, receptor-binding activity, and functional delivery. This approach supports controlled VHH orientation and targeted LNP development.
Yes. BOC Sciences provides customized VHH-conjugated LNP development support based on the target receptor, cell type, payload, and research objectives. Our services can include VHH selection and engineering, monovalent or multivalent targeting architecture design, conjugation site selection, VHH-PEG-lipid preparation, surface functionalization, and ligand density optimization. For customers with existing VHH candidates, we can evaluate suitable conjugation approaches based on their structural and binding characteristics. For projects without an established design, we can help compare potential targeting architectures and conjugation strategies. We also support payload-compatible formulation development and cell-based evaluation to identify promising candidates for targeted mRNA, siRNA, or other delivery applications.
BOC Sciences supports VHH-LNP characterization through physicochemical analysis, surface ligand evaluation, and functional delivery testing. Available development approaches can include particle size and PDI measurement, zeta potential analysis, morphology assessment, payload encapsulation evaluation, VHH conjugation analysis, and formulation stability studies. Depending on project requirements, receptor-binding assays, cellular uptake studies, intracellular localization analysis, and mRNA expression or siRNA silencing assays can also be incorporated. When challenges arise, such as aggregation, reduced VHH activity, inconsistent ligand density, or weak functional delivery despite strong cellular uptake, we help investigate the contributing factors through conjugation strategy comparisons, PEG spacer optimization, ligand density screening, formulation adjustments, and appropriate control experiments. Detailed process documentation and analytical reports support further development decisions.
