Customized protein-conjugated lipid nanoparticle (Protein-LNP) development for receptor-directed delivery, functional protein surface display, controlled conjugation density, payload-compatible formulation, and cell-specific performance evaluation.
Protein-conjugated lipid nanoparticles are LNP systems carrying proteins or protein-derived ligands on their outer surface. Antibodies, receptor-binding proteins, cytokines, enzymes, and other functional proteins may be displayed to introduce recognition, signaling, or catalytic properties. Unlike protein-loaded LNPs, which primarily encapsulate proteins as cargo, protein-conjugated LNPs use a surface-associated protein to influence how the particle interacts with its environment.
Protein attachment alone does not establish effective targeting. The protein must retain its structure and relevant activity, remain accessible above the surface coating, and work with an LNP core capable of delivering its payload. BOC Sciences integrates protein selection, linker and lipid design, conjugation chemistry, formulation screening, and biological evaluation within its targeted LNP development workflow.
We support research programs involving mRNA, siRNA, other nucleic acids, proteins, small molecules, and imaging probes. Development studies are tailored to the surface protein, its intended function, the target cell model, and measurable project endpoints.
Protein-Functionalized LNP Structure Illustration
Our service portfolio addresses the full Protein-LNP design workflow, from choosing a protein with a defined biological role to confirming that the final surface-modified particle preserves protein function and delivers its cargo in the intended research model.
We match candidate proteins to receptor expression, biological activity, molecular size, and accessible conjugation sites.
Our nanoparticle conjugation services help develop suitable protein attachment conditions while protecting the LNP core and the protein.
We align the surface protein architecture with ionizable lipid composition, helper lipids, cholesterol, PEG-lipids, and cargo-loading requirements through LNP formulation development.
Characterization must distinguish an intact, surface-displayed protein from inactive, loosely adsorbed, or unbound material.
Target-cell recognition, particle internalization, and productive cargo activity are assessed as separate outcomes.
We develop preparation conditions that allow meaningful comparison of protein-LNP candidates across repeat experiments.
BOC Sciences supports a wide range of protein formats for protein-LNP surface display, from receptor-binding proteins and immunomodulatory proteins to enzymes and surface-stabilizing proteins. Based on each project's target cell model, receptor biology, and delivery goal, we help clients select suitable protein formats and surface display strategies for protein-LNP development.
These LNPs display proteins that recognize selected cell-surface receptors and may promote receptor-associated cell interaction.
Surface-associated cytokines or chemokines can be investigated for localized receptor engagement and immune-cell response modulation.
Enzyme-bearing LNPs are designed to place an active catalytic protein at the particle interface, where substrate accessibility can be evaluated.
Carrier-type proteins may alter the nanoparticle interface and its interactions with surrounding biomolecules.
Growth factors and related signaling ligands can be displayed to explore controlled receptor engagement and downstream cellular responses.
Selected cytotoxic proteins may be explored for targeted cell-interaction research, but their biological mechanism determines whether surface display is appropriate.
Whether you need a custom protein-LNP system, have a protein but are unsure how to incorporate it into an LNP design, or want to conjugate proteins to existing LNPs, BOC Sciences can help with protein selection, surface conjugation, formulation development, and optimization.
Protein attachment strategy affects display orientation, surface density, particle stability, and payload compatibility. BOC Sciences supports four major routes, each suited to specific protein formats and research goals. We help select and compare routes for the same project to identify the approach that best fits the receptor, payload, and target-cell model.
I. Direct Protein Conjugation to Preformed LNPs
In this route, the LNP is prepared first, and the protein is coupled to its surface using a reactive lipid already embedded in the bilayer. Common chemistries include thiol–maleimide coupling to Mal-PEG-lipid, SPAAC click chemistry between DBCO-PEG-lipid and azide-functionalized protein, and EDC/NHS coupling between amine-functionalized PEG-lipid and carboxylate groups on the protein. This route allows the core payload–lipid formulation to be optimized independently of protein chemistry, and is suitable when the protein cannot tolerate the solvent or shear conditions of LNP self-assembly.
II. Protein–Lipid Conjugate Post-Insertion
Here, a protein–lipid anchor conjugate (such as protein–PEG2000–DSPE, protein–cholesterol, or protein–DSPE) is synthesized first, then inserted into preformed LNPs under controlled temperature and mixing. This route is widely used for full-length proteins, Fc-fusion proteins, and VHH antibody fragments. It typically preserves protein bioactivity and allows independent tuning of particle size, payload loading, and protein surface density. Post-insertion efficiency depends on anchor type, temperature, and incubation time, all of which BOC Sciences screens for each protein format.
III. Affinity-Mediated Protein Surface Attachment
Affinity-mediated assembly uses non-covalent but high-affinity interactions such as biotin–streptavidin, His-tag–Ni-NTA, or Fc–protein A/G. A biotin-PEG-lipid or His-tag-PEG-lipid is first embedded in the LNP, then the affinity-tagged protein is added to assemble the display. It is modular, reversible, and ideal for screening multiple protein ligands on the same LNP scaffold. This is also the route of choice when a gentle, near-physiological assembly condition is needed for sensitive proteins.
IV. Electrostatic Protein Adsorption onto LNP Surfaces
In this route, the protein is adsorbed to the LNP surface through electrostatic and hydrophobic interactions, often at a specific pH or ionic strength. Proteins with a net charge opposite to the LNP surface at that pH can form a stable surface layer without chemical modification. This route is simple and low-cost, but orientation is random and the adsorbed layer can desorb upon dilution or pH change. We use this route mainly for feasibility studies, pilot screening, and as a benchmark against covalent methods.
Protein surface engineering can add biological functions that are difficult to achieve through lipid composition alone. The value of each modification depends on the protein's active presentation and the biological model rather than the presence of protein on the particle surface.
Receptor-Directed Cell Recognition
Receptor-binding proteins and antibody fragments provide molecular recognition elements for targeted interaction with selected cells. BOC Sciences evaluates this function against receptor-low controls and considers whether higher binding also produces productive intracellular delivery.
Diverse Surface Biological Functions
Protein display is not limited to targeting. Surface-associated cytokines, enzymes, growth factors, and carrier proteins can support research into signaling, catalysis, microenvironment interaction, or nanoparticle interfaces. Each function requires its own activity assay.
Modular Protein and Linker Engineering
Protein identity, fragment size, attachment site, PEG spacer, and ligand density can be varied without completely redesigning the cargo. This helps identify structure-function relationships and compare different surface architectures using a common LNP backbone.
Compatibility with Multiple Research Payloads
When formulation compatibility is demonstrated, the same protein-targeting concept may be investigated with reporter mRNA, siRNA, imaging probes, or selected small-molecule cargoes. Surface function, payload protection, and intracellular release are optimized independently and then assessed together.
BOC Sciences develops protein-conjugated LNPs for many payload classes used in targeted delivery research. Each payload class needs a suitable loading strategy, particle design, and functional readout. We help match protein surface engineering with the payload type and the target-cell model.
| Payload Type | Supported Uses & Protein-LNP Development Considerations | Request Information |
|---|---|---|
| Protein-LNP Development for siRNA | Suitable for gene-silencing studies in receptor-positive cell models, target-gene knockdown validation, and RNAi-based therapeutic research. Development focuses on siRNA encapsulation, surface protein integrity, ligand density, and receptor-specific knockdown using matched control LNPs. | Inquiry |
| Protein-LNP Development for mRNA and Reporter RNA | Designed for reporter expression, protein expression, antigen-related delivery, and formulation comparison studies. Development considers mRNA integrity, encapsulation efficiency, protein surface exposure, particle stability, and expression readouts in receptor-positive cell models. | Inquiry |
| Protein-LNP Development for circRNA and Self-Amplifying RNA | Applicable to RNA delivery systems that need strong payload protection and target-cell expression. BOC Sciences supports lipid nanoparticles for circRNA delivery with protein surface modification, stability evaluation, and cell-based expression testing. | Inquiry |
| Protein-LNP Development for gRNA/mRNA Combination | Supports co-loaded nucleic acid systems used in CRISPR-related delivery research. We evaluate co-encapsulation behavior, protein–lipid compatibility, particle attributes, and functional readouts under matched control conditions. | Inquiry |
| Protein-LNP Development for Protein and Peptide | Suitable for protein antigens, enzymes, peptides, binding proteins, and functional protein payloads used in targeted delivery research. Formulation work focuses on mild loading conditions, aggregation control, activity retention, and protein-mediated uptake evaluation. | Inquiry |
| Protein-LNP Development for Small Molecule | Designed for hydrophobic, amphiphilic, or ionizable small molecules used in targeted delivery research. We consider drug–lipid compatibility, loading method, leakage control, particle stability, protein surface modification, and release behavior. | Inquiry |
| Protein-LNP Development for Fluorescent and Imaging | Supports fluorescent dyes, labeled RNA, labeled proteins, and other tracking payloads used to study protein-LNP uptake, intracellular localization, biodistribution patterns, and formulation comparison in target-cell models. | Inquiry |
| Protein-LNP Development for Custom Payload | Developed for unusual payloads, multiple payload systems, or early feasibility studies. We evaluate payload compatibility, loading sequence, protein modification route, particle stability, and target-cell delivery performance. | Inquiry |
We can evaluate whether the protein, linker, LNP core, and cargo-loading method can work together and define a useful screening plan for your research objectives.
A protein-LNP may appear successful in an attachment assay yet perform poorly in biological testing. We use linked chemistry, particle, and functional measurements to identify which part of the design limits performance.
✔ Reduced Payload Encapsulation
Surface modification can change the self-assembly environment needed for payload loading. We optimize lipid composition, aqueous phase pH, payload input, and process conditions for LNP encapsulation efficiency optimization across payload formats.
✔ Ligand Density and Stability Conflict
High protein density may improve receptor interaction in some models, but too much surface modification can increase aggregation or reduce storage stability. We select candidates using particle data, ligand display data, and cell-based readouts together.
✔ Loss of Protein Activity After Conjugation
Some conjugation chemistries (random NHS ester coupling, maleimide on solvent-exposed cysteines) can reduce binding activity. We evaluate site-specific chemistries such as Sortase A ligation, click chemistry on engineered residues, and Fc-binding systems, and we screen conditions that preserve binding affinity.
✔ Unclear Receptor Contribution
Cells can take up nanoparticles through several pathways. This makes mechanism analysis difficult. We design matched unmodified LNPs, isotype protein-LNPs, receptor-different cell models, receptor-blocking controls, and free-protein competition assays to support clearer interpretation.
✔ High Uptake but Weak Payload Function
Strong uptake does not always lead to strong mRNA expression, siRNA knockdown, or protein activity. We evaluate RNA integrity, intracellular localization, endosomal release, and functional delivery to find the real bottleneck, with reference to LNP endosomal escape evaluation approaches.
✔ Poor Batch Consistency in Protein Display
Protein-LNP batches can vary in protein surface density even when the core formulation is fixed. We anchor protein display to measurable parameters (anchor-to-lipid ratio, insertion time, temperature, buffer condition) and track batch-to-batch protein density as a release attribute.
Tell us which step is limiting your results: protein activity, free-protein removal, surface display, particle stability, receptor binding, or intracellular payload function.
We review the target cell population, receptor or protein function, payload properties, existing protein material, and planned biological readout. The initial plan specifies protein format, functional reference assays, expected particle attributes, and the controls needed to interpret protein-mediated activity.
Based on protein chemistry and the intended function, we select an attachment route, lipid anchor, PEG spacer, and conjugation-site strategy. We define a focused comparison of ligand densities or attachment formats, including how unbound protein will be removed and how retained activity will be verified.
Candidate LNP cores are prepared and loaded with the selected cargo, followed by protein attachment or insertion under compatible conditions. We compare the resulting particle size, PDI, protein association, payload retention, and colloidal behavior, and narrow the design range before functional testing.
We compare protein-bearing LNPs, unmodified LNPs, and relevant receptor or free-protein controls. The assessment may include receptor binding, uptake, intracellular localization, cargo function, and stability after test-medium exposure. The project output links each design choice to measured performance and identifies the next optimization priority.
Protein-conjugated LNPs can be used for tumor targeting research, CNS delivery research, immune-cell targeting research, and receptor-trafficking studies. BOC Sciences helps researchers develop protein-LNP systems for a wide range of applications based on different project goals.
BOC Sciences develops customized protein-conjugated LNPs for diverse research applications. Our experts can help design and optimize protein-LNP systems based on your target, payload, and research objectives.
Challenge: A neuroscience research team was developing an mRNA delivery system for CNS-related applications. Their standard LNP showed strong liver accumulation and very low brain-related signal in their research model. The team wanted to redirect the LNP toward transferrin receptor (TfR)–expressing brain endothelial cells using a transferrin-based surface display strategy, while keeping mRNA integrity and particle uniformity intact.
Diagnosis: BOC Sciences found that the original LNP had no receptor-specific ligand and was being cleared mainly through ApoE-mediated liver uptake. At the same time, the PEG-lipid content was high enough to leave little room for protein surface display. The team needed a route that would expose transferrin to the TfR while still protecting the mRNA payload.
Solution: BOC Sciences developed transferrin-conjugated lipid nanoparticles using a protein–PEG2000–DSPE post-insertion strategy. We screened three transferrin-to-lipid ratios, two PEG linker lengths, and two insertion temperatures. Each candidate was evaluated by particle size, PDI, mRNA encapsulation, transferrin surface density, and reporter expression in a TfR-positive endothelial cell model. Unmodified LNP was run in parallel as a control.
Result: The selected transferrin-LNP maintained an average particle size of about 110 nm with a PDI below 0.18. mRNA encapsulation remained above 85%, and TfR-positive cell uptake increased by roughly 3.2-fold compared with the unmodified LNP. The client obtained a more brain-relevant LNP candidate suitable for further CNS mRNA delivery research.
Challenge: A cell therapy research group wanted to deliver mRNA encoding a CAR-related payload into primary T cells using a non-viral delivery system. Their initial full-IgG-conjugated LNP showed measurable binding to T cells, but the antibody orientation was inconsistent and uptake was highly variable between donors. The team needed a smaller, more uniform targeting ligand that could be displayed in a defined orientation on the LNP surface.
Diagnosis: BOC Sciences reviewed the construct design and found that the random lysine-conjugation of the full IgG had partially masked the CD3-binding site. The full-length antibody also contributed noticeable hydrodynamic mass, increasing the average particle size. A more compact, site-specific ligand format was needed.
Solution: BOC Sciences designed an anti-CD3 VHH-LNP construct using Sortase A-mediated conjugation to a GGG-PEG2000-DSPE anchor. The VHH format (~15 kDa) reduced added mass, and the Sortase A route was designed to enable site-specific attachment away from the binding CDR loops. We screened three VHH surface densities, three PEG linker lengths, and three insertion times, then benchmarked candidates against a non-targeting VHH-LNP and an unmodified LNP.
Result: The selected VHH-LNP kept an average particle size around 95 nm with a PDI below 0.16. CD3-positive T-cell uptake improved by roughly 4.5-fold compared with the unmodified LNP, and the mRNA payload produced detectable reporter expression in primary T cells. The client received a defined-orientation, reproducible VHH-LNP format suitable for further T cell engineering research.
Extensive Inventory of Lipids and ProteinsBOC Sciences supplies research chemicals and offers an extensive product portfolio spanning lipid nanoparticle materials, ionizable lipids, phospholipids, cholesterol derivatives, PEG-lipids, proteins, and conjugation reagents. Our lipid nanoparticle product resources and custom material options help researchers select components suited to their protein-LNP design. Specific item availability is confirmed during project review.
Flexible Protein Ligand and Surface Engineering StrategiesWe evaluate different protein formats, conjugation handles, PEG spacer designs, attachment routes, and ligand densities. This flexibility helps align protein activity with the intended surface presentation rather than using one attachment method for every project.
Customized Protein-LNP Formulation and Payload CompatibilityOur development process considers the protein surface and the LNP core together, including lipid composition, encapsulation, protein stability, and intracellular cargo function for RNA, protein, small-molecule, and custom research systems.
Comprehensive Protein Function and Targeting EvaluationWe connect surface chemistry to receptor-binding or protein activity tests, physical particle measurements, cell association, trafficking, and functional payload outcomes. Proper controls help clarify whether an observed effect originates from the conjugated protein.
Reproducible Formulation Development and OptimizationWe structure screening around measurable variables and repeatable preparation conditions so clients can compare candidates by conjugation performance, particle characteristics, protein activity, payload retention, and target-cell readouts.
Various functional proteins can be conjugated to lipid nanoparticle surfaces, including antibodies and antibody fragments (Fab, scFv, and VHH), receptor-binding proteins such as transferrin, cytokines, chemokines, enzymes, carrier proteins, and growth factors. These proteins may provide receptor recognition, immune modulation, catalytic activity, or cell signaling functions. Protein selection depends on the intended biological function, target receptor expression, molecular size, structural stability, and available conjugation sites. For example, receptor-targeting proteins must retain access to their binding domains, while enzyme-functionalized LNPs require preservation of catalytic activity. Some cytotoxic proteins act only after intracellular delivery, so their mechanisms must be considered before selecting permanent surface conjugation.
Proteins can be attached to LNP surfaces through direct covalent conjugation, protein-lipid conjugate post-insertion, affinity-mediated attachment, or electrostatic adsorption. Direct conjugation commonly uses thiol-maleimide coupling, NHS ester-amine reactions, or copper-free click chemistry to connect proteins with functionalized surface lipids. Post-insertion involves preparing protein-lipid conjugates separately and incorporating their lipid anchors into preformed LNPs. Affinity-mediated approaches use specific molecular interactions, while electrostatic adsorption relies on charge-dependent association. Each approach differs in attachment stability, protein orientation, reaction conditions, and compatibility with the LNP formulation. Method selection should consider protein structure, reactive group availability, intended surface density, payload stability, and the biological environment in which the modified particles will be evaluated.
Protein-LNP evaluation should combine physicochemical characterization, protein activity testing, and functional delivery studies. Particle size, polydispersity index, zeta potential, protein association, and payload retention provide information about formulation quality. Receptor-binding assays, flow cytometry, and confocal microscopy can assess target-cell recognition, uptake, and intracellular localization. For mRNA or siRNA delivery, reporter expression or gene knockdown should also be measured to determine whether internalized particles produce the intended biological response. Appropriate controls include unmodified LNPs, non-targeting protein-conjugated LNPs, and receptor-blocking experiments. These comparisons help distinguish receptor-mediated interactions from nonspecific nanoparticle uptake. Importantly, increased cellular uptake does not necessarily translate into improved endosomal escape or functional payload delivery.
Yes. If you already have an antibody, antibody fragment, transferrin, enzyme, or another functional protein but have not established a suitable LNP formulation, BOC Sciences can help develop a customized protein-conjugated LNP system. Our services include evaluating protein structure and conjugation sites, selecting lipid anchors and PEG linkers, designing compatible LNP formulations, optimizing protein surface density, and assessing protein activity after conjugation. We can also investigate how the selected protein affects particle stability, payload encapsulation, receptor binding, and functional delivery. To initiate a project, researchers can share information about their protein, intended target cells, payload type, and experimental objectives. Our team can then evaluate technical feasibility and recommend an appropriate development strategy.
Yes. BOC Sciences can evaluate protein surface modification for customers who already have an established LNP formulation or preformed lipid nanoparticles. The initial assessment considers lipid composition, available surface functional groups, PEG-lipid structure, particle size, payload characteristics, and formulation stability. Depending on the existing LNP system and the protein's chemical properties, we can explore direct covalent coupling, incorporation of functionalized lipid components, or protein-lipid conjugate post-insertion. Development work may include optimizing reaction conditions, protein attachment levels, and removal of unbound protein. We can also characterize protein activity, particle stability, payload integrity, and cell-based delivery performance after modification, helping researchers determine whether their existing LNP formulation can support the intended protein functionality.
