Oligonucleotide CDMO Services

Oligonucleotide Services

Sophia provides oligonucleotide CDMO services for sponsors developing antisense oligonucleotides, siRNA, miRNA mimics, antagomirs, aptamers, splice-switching oligonucleotides, exon-skipping candidates, immune-stimulatory oligos, CpG oligonucleotides, guide RNA, CRISPR-associated nucleic acids, GalNAc-conjugated oligos, peptide-conjugated oligos, lipid-conjugated oligos, diagnostic oligos, and next-generation genetic medicine platforms.

Oligonucleotides are short strands of chemically designed DNA or RNA, but that simple definition undersells the category. These molecules can silence genes, alter splicing, block translation, recruit RNase H, guide CRISPR systems, modulate immune receptors, bind proteins as aptamers, act as diagnostic probes, or serve as essential materials for advanced therapies. They are small enough to look chemically manageable, but complex enough to behave like their own class of medicine.

Bold text reads “Precision That Pulls You Forward. Tight Control That Pushes Every Program Further.” with supporting copy about process development, GMP manufacturing and technology transfer.

That is the technical edge. An oligonucleotide is not a small molecule in the old-school sense, not a biologic in the antibody sense, and not a viral vector. It is a sequence-defined, chemistry-heavy, impurity-sensitive, analytically demanding therapeutic or reagent platform. Each base addition, backbone modification, protecting group, coupling efficiency, deprotection condition, impurity, counterion, conjugate, and formulation choice can affect final quality.

Sophia’s Oligonucleotide CDMO Services support programme review, sequence and chemistry strategy, solid-phase synthesis planning, phosphoramidite route review, modified base strategy, backbone chemistry, GalNAc and peptide conjugation interface, purification, desalting, ultrafiltration, lyophilisation, analytical development, impurity profiling, identity testing, mass confirmation, formulation, stability, GMP/GMP-like documentation, and scale-up.

The aim is direct: turn sequence into controlled nucleic acid product.

Why Oligonucleotides Matter

Oligonucleotides matter because they let drug developers act at the level of genetic information. A traditional small molecule often binds a protein. An antibody often binds a protein or cell surface target. An oligonucleotide can bind RNA, alter gene expression, correct splicing, degrade transcripts, block translation, guide editing machinery, or recognise molecular sequences with extreme precision.

That opens therapeutic territory that was hard to reach with older modalities. Oligonucleotides can target disease-associated RNA, rare genetic mutations, liver-expressed genes, neuromuscular disease mechanisms, viral sequences, oncogenic transcripts, inflammatory pathways, and genetic regulators. They are also essential in diagnostics, synthetic biology, cell therapy, gene editing, and vaccine development.

The first FDA-approved antisense drug, fomivirsen, was approved in 1998 for cytomegalovirus retinitis, establishing an early clinical milestone for antisense oligonucleotide therapeutics. Since then, the field has become more sophisticated through backbone modifications, sugar modifications, conjugates, delivery technologies, better analytics, and clearer regulatory thinking. FDA published guidance in 2024 on clinical pharmacology considerations for oligonucleotide therapeutics, while EMA published a 2024 guideline addressing manufacturing, characterisation, specifications, and analytical control for synthetic oligonucleotides.

That regulatory attention matters. It signals that oligonucleotides are no longer fringe molecules. They are a serious therapeutic class with specific CMC, analytical, and clinical development needs.

History of Oligonucleotide Therapeutics

The oligonucleotide story begins with molecular biology’s central insight: sequence matters. Once researchers understood that nucleic acids encode, transmit, and regulate biological information, it became natural to ask whether synthetic sequences could be used as medicines or tools.

Early antisense work explored whether short nucleic acid strands could bind complementary RNA and block gene expression. The idea was clean, but the early molecules were unstable, hard to deliver, and sometimes biologically messy. Natural DNA and RNA are vulnerable to nucleases. They do not automatically enter cells well. They can trigger immune responses. They can bind unintended sequences. They can accumulate in tissues. They can create unexpected toxicology.

Chemistry solved some of this. Phosphorothioate backbones improved nuclease resistance. 2′-O-methyl, 2′-O-methoxyethyl, locked nucleic acids, constrained ethyl modifications, morpholino chemistries, peptide nucleic acids, and other designs expanded the field. RNA interference added another mechanism, where double-stranded RNA-like molecules could guide sequence-specific mRNA degradation. Splice-switching oligonucleotides created routes for exon skipping or splicing correction. Aptamers showed that nucleic acids could fold into binding structures, not only act as sequence complements.

The field also learned a hard lesson: delivery is not a side quest. GalNAc conjugation changed the liver-targeted oligonucleotide world by enabling uptake through the asialoglycoprotein receptor on hepatocytes. Lipid conjugates, peptide conjugates, antibodies, nanoparticles, and local delivery routes continue to shape development.

Today, oligonucleotides are not one modality. They are a family: ASO, siRNA, miRNA, aptamer, guide RNA, splice-switching oligo, immune-stimulatory oligo, conjugated oligo, diagnostic oligo, and synthetic biology reagent. The sequence may be short. The product category is not.

The Chemistry of Oligonucleotides

Oligonucleotide chemistry is built from nucleobases, sugars, phosphate linkages, protecting groups, and modifications. A natural nucleic acid strand contains bases connected through a sugar-phosphate backbone. Therapeutic oligonucleotides often modify that architecture to improve stability, potency, tissue distribution, binding affinity, nuclease resistance, or safety.

Backbone modifications include phosphorothioate linkages, where a non-bridging oxygen in the phosphate is replaced by sulfur. This can improve nuclease resistance and protein binding, but it also creates stereochemical complexity because each phosphorothioate linkage can introduce chirality. Sugar modifications include 2′-O-methyl, 2′-O-methoxyethyl, 2′-fluoro, locked nucleic acid, constrained ethyl, and related chemistries. Base modifications may improve affinity, reduce immune activation, or change stability. Morpholino and peptide nucleic acid chemistries move even further away from natural nucleic acid structures.

Synthesis is typically performed by solid-phase phosphoramidite chemistry. A protected nucleoside is attached to a solid support. Each cycle adds a new protected phosphoramidite building block through coupling, oxidation or sulfurisation, capping, and detritylation. After chain assembly, the oligonucleotide is cleaved from the support and deprotected. Solid-phase synthesis remains the preferred method for oligonucleotide manufacture, although scale, reagent use, and waste burden remain important challenges for large-scale production.

The chemistry is a bit like building a sentence one letter at a time, except every letter has protecting groups, moisture sensitivity, coupling efficiency, and impurity consequences. A tiny failure at each step can accumulate across the sequence. That is why Oligonucleotide CDMO Services require process control from the first base to the final lyophilised material.

Oligonucleotide Product Types Supported

Sophia supports oligonucleotide CDMO services across therapeutic, diagnostic, research, and advanced modality programmes.

Antisense oligonucleotides may use RNase H-mediated degradation, steric blocking, splice modulation, translation blocking, or other mechanisms. These products may include phosphorothioate ASOs, gapmers, splice-switching oligos, exon-skipping oligos, and chemically modified single-stranded designs.

siRNA products may use double-stranded RNA interference mechanisms, often with modified strands and conjugates such as GalNAc for liver targeting. miRNA products may include mimics, inhibitors, antagomirs, or regulatory RNA tools.

Aptamers may be DNA or RNA-based binding molecules designed to fold into structures that recognise proteins, small molecules, cells, or other targets. Guide RNA products may support CRISPR, base editing, prime editing, or related genetic engineering systems. CpG and immune-stimulatory oligos may target innate immune pathways.

Conjugated oligonucleotides may include GalNAc conjugates, lipid conjugates, peptide conjugates, antibody-oligo conjugates, cholesterol oligos, tocopherol conjugates, and other delivery-enhancing designs. Diagnostic oligos may include probes, primers, labelled oligos, capture sequences, molecular barcodes, and assay controls.

Programme stages may include discovery material, research-grade oligos, preclinical material, toxicology batch planning, GMP-ready synthesis, analytical method development, formulation screening, stability studies, and scale-up.

The category is broad, but the manufacturing question is consistent: can the sequence and chemistry be produced with controlled identity, purity, impurity profile, stability, and documentation?

Sequence and Chemistry Review

Sophia supports sequence and chemistry review for oligonucleotide programmes. This includes length, GC content, secondary structure, self-complementarity, homopolymer runs, modified nucleotide placement, backbone strategy, stereochemistry where relevant, conjugation site, terminal modifications, nuclease resistance, immune-stimulation risk, off-target concerns, manufacturability, purification risk, and analytical strategy.

Some sequences are simply harder to make than others. High GC content can create secondary structure. Long sequences accumulate synthetic impurities. Certain modifications can reduce coupling efficiency. Repetitive sequences can complicate analysis. Highly hydrophobic conjugates can make purification difficult. Double-stranded products require annealing and strand-ratio control. Guide RNAs may require different synthesis, transcription, or purification routes depending on length and format.

The review should occur before a sequence becomes expensive. A sponsor may arrive with a beautiful biological design that is awkward to manufacture. Sometimes the answer is chemistry adjustment. Sometimes it is purification strategy. Sometimes it is accepting a more difficult process because the biology demands it. But the trade-offs should be visible early.

A strong oligonucleotide CDMO services route does not treat sequence as sacred until manufacturability has had a say.

Solid-Phase Synthesis Strategy

Sophia supports solid-phase synthesis strategy for oligonucleotides, including support selection, loading, phosphoramidite quality, activator choice, coupling time, detritylation, capping, oxidation, sulfurisation, modified monomer incorporation, moisture control, cycle efficiency, cleavage, deprotection, and scale-up.

Each synthetic cycle must work well. If a sequence is twenty bases long, small inefficiencies may be manageable. If a sequence is long or heavily modified, cumulative failure can become a major impurity issue. Deletion sequences, truncated sequences, depurinated products, n-1 species, n+1 species, desulfurised species, oxidised species, and incomplete deprotection products can all appear.

Phosphorothioate-containing oligos require sulfurisation steps, and incomplete sulfurisation or oxidation can create mixed backbone impurities. RNA synthesis is often more sensitive because 2′-protecting groups and deprotection conditions can be difficult. Modified monomers may require adjusted coupling. Conjugated oligos may require special handling or post-synthetic modification.

Moisture is a quiet enemy. Phosphoramidite chemistry does not enjoy water. Reagent quality, solvent dryness, instrument maintenance, and cycle control are not glamorous, but they decide whether the batch behaves.

This is proper chemistry: repetitive, sensitive, and unforgiving.

Purification and Desalting

After synthesis and deprotection, an oligonucleotide is not finished. Sophia supports purification and desalting strategies including ion-exchange chromatography, reverse-phase chromatography, HPLC, preparative chromatography, anion exchange, size-based methods, ultrafiltration/diafiltration, desalting, precipitation where appropriate, lyophilisation, and buffer or salt-form control.

Purification choice depends on sequence, length, chemistry, conjugate, impurity profile, scale, and target purity. Ion-exchange methods are often useful because oligonucleotides are highly charged. Reverse-phase methods may be useful for certain protected or hydrophobic forms, trityl-on strategies, conjugated oligos, or analytical separation. Desalting and UF/DF may be needed to remove small molecules, salts, solvents, and reagents.

Purification gets harder as sequence length increases or impurity profiles become more similar to the desired product. Deletion impurities may differ by one nucleotide.

Phosphorothioate diastereomeric complexity can broaden analytical peaks. Conjugates may add hydrophobicity, aggregation, or adsorption risk. Double-stranded products may require removal of excess sense or antisense strand.

A clean oligo is not just one that gives a nice mass. It must meet purity, identity, impurity, salt, water, residual solvent, and stability expectations for the intended use.

Conjugated Oligonucleotide Development

Sophia supports conjugated oligonucleotide development, including GalNAc conjugates, peptide conjugates, lipid conjugates, cholesterol conjugates, tocopherol conjugates, antibody-oligonucleotide conjugates, aptamer conjugates, dye-labelled oligos, biotinylated oligos, and chelator or diagnostic-label conjugates.

Conjugation can improve targeting, uptake, biodistribution, or assay function. GalNAc conjugation has become especially important for liver-targeted oligonucleotides. Peptide conjugates may support cell penetration or tissue targeting. Lipid conjugates may improve membrane interaction or distribution. Antibody-oligo conjugates may support targeted delivery, diagnostics, or research applications.

But conjugation changes manufacturing. Hydrophobic conjugates may complicate purification. Peptide conjugates may introduce proteolysis, charge, aggregation, or stereochemistry issues. Antibody-oligo conjugates require both biologics and nucleic acid analytics. GalNAc conjugates require conjugation site control, purity, and identity testing.

Labelled oligos require dye or reporter stability.

Double-Stranded Oligos, Annealing, and Strand Control

siRNA and certain RNA duplex products require control of two strands. Sophia supports strand synthesis, purification, annealing, strand-ratio control, duplex formation, desalting, filtration, lyophilisation, analytical confirmation, and stability testing.

Double-stranded oligos add a second layer of identity. The sense and antisense strands must each be correct. The duplex must form correctly. Excess single strand must be controlled. Mismatched or truncated strand impurities can affect potency, safety, and analytical interpretation. Annealing conditions such as temperature, salt, concentration, cooling rate, and buffer composition can affect duplex quality.

siRNA products may include overhangs, modified bases, 2′-F, 2′-OMe, phosphorothioate linkages, conjugates, and terminal modifications. Some designs require precise strand selection in the RNA-induced silencing complex. Impurities can matter not only chemically but biologically.

A duplex product is not “two oligos in a tube.” It is a defined hybridised active substance.

Analytical Development

Sophia’s oligonucleotide services include analytical development for identity, purity, impurity profile, mass, sequence confirmation, counterion, water content, residual solvents, residual reagents, endotoxin where relevant, bioburden or sterility where relevant, duplex formation, conjugate identity, and stability.

Methods may include LC-MS, UPLC, ion-exchange HPLC, reverse-phase HPLC, capillary electrophoresis, gel electrophoresis, MALDI-TOF where suitable, UV spectroscopy, NMR for selected structural questions, ICP-MS for elemental impurities, Karl Fischer water testing, residual solvent testing, pH, osmolality, endotoxin, bioburden, and product-specific assays.

Impurity analysis is central. Oligonucleotide impurities may include deletion sequences, shortmers, longmers, depurinated products, incomplete deprotected products, oxidised or desulfurised species, phosphodiester impurities, abasic sites, failed conjugates, residual protecting groups, residual linker, and synthesis-related byproducts. For therapeutic products, impurity control must be justified and documented.

Analytical control is also a regulatory focus. EMA’s 2024 oligonucleotide guideline specifically addresses manufacturing, characterisation, specifications, and analytical control for synthetic oligonucleotides. That is exactly the territory where sponsors need strong technical documentation.

The assay package must show what the molecule is and what else is in the vial.

Formulation and Stability

Sophia supports formulation development for oligonucleotide products in liquid, frozen, lyophilised, injectable, ophthalmic, intrathecal, subcutaneous, inhaled-adjacent, topical research, diagnostic, and reagent formats depending on product category.

Oligonucleotides may be formulated in buffers with controlled pH, salt, tonicity, concentration, counterion, stabilisers, surfactants where appropriate, chelators, antioxidants, cryoprotectants, lyoprotectants, and container-closure systems. Stability risks may include hydrolysis, depurination, oxidation, desulfurisation, strand separation, aggregation, adsorption, microbial contamination, and degradation of conjugated groups.

Lyophilisation may be useful for some oligonucleotide products, especially where stability, shipping, or reconstitution matters. Liquid formulations may be preferred for ready-to-use injectables or diagnostics. For high-concentration subcutaneous products, viscosity, osmolality, injection volume, and excipient compatibility may matter.

For intrathecal products, purity and formulation tolerability can be especially sensitive.

Oligonucleotide formulation is quieter than ADC formulation, but do not mistake quiet for easy. The molecule is charged, sequence-defined, chemically modified, and often biologically potent. It needs a tidy home.

Delivery Interface

Oligonucleotide development often depends on delivery. Sophia supports delivery interface planning for GalNAc conjugates, lipid nanoparticles, polymeric systems, peptide conjugates, antibody-oligo conjugates, local delivery, intrathecal delivery, subcutaneous delivery, pulmonary concepts, ocular delivery, topical research formats, and diagnostic use.

The delivery route influences chemistry. A GalNAc-conjugated siRNA or ASO may be optimised for liver uptake. An intrathecal ASO may require different purity, volume, and formulation logic. A guide RNA for ex vivo editing may need compatibility with transfection, electroporation, lipid systems, or RNP complex formation. An oligo loaded into an LNP must be compatible with encapsulation, pH gradients, ionisable lipids, and particle stability.

The delivery system should not be treated as packaging. For many oligonucleotides, delivery is part of the medicine.

This is where Sophia’s broader platform becomes useful: oligo chemistry can interface with lipid nanoparticles, peptide conjugates, bioconjugation, sterile drug product, and gene therapy analytics rather than sitting in isolation.

GMP, CMC, and Documentation

Sophia supports GMP/GMP-like and CMC documentation for oligonucleotide Services across preclinical, clinical, diagnostic, research, and commercial-readiness pathways. Documentation may include sequence records, chemistry description, raw material controls, phosphoramidite qualification, solid support records, synthesis process description, deprotection process, purification process, impurity strategy, analytical methods, specifications, formulation report, stability protocol, batch records, CoA, deviation handling, change control, and tech transfer package.

For therapeutic oligonucleotides, CMC documentation must address active substance manufacture, impurities, control strategy, analytical methods, specifications, stability, and product presentation. FDA’s 2024 guidance highlights clinical pharmacology considerations for oligonucleotide therapeutics, while EMA’s guideline addresses quality and manufacturing aspects for synthetic oligonucleotides.

For diagnostic oligos, lot consistency, purity, probe performance, labelling efficiency, and assay compatibility may matter most. For guide RNA and CRISPR reagents, nuclease-free handling, identity, purity, endotoxin where relevant, and functional compatibility may be central. For conjugated oligos, the conjugate itself must be controlled as part of the product identity.

The dossier should make the molecule legible: sequence, chemistry, process, impurities, formulation, stability, and use.

Why Sophia for Oligonucleotide CDMO Services

Sophia supports oligonucleotide programmes through nucleic acid chemistry planning, conjugation strategy, analytical development, formulation, European facility execution, and GMP/GMP-like documentation. The platform is designed for sponsors who need oligonucleotide work to move from sequence to controlled product without losing the scientific thread.

The service includes:

Oligonucleotide programme review
ASO, siRNA, miRNA, aptamer, guide RNA, and CpG oligo support
Sequence and chemistry developability review
Solid-phase synthesis strategy
Modified base, sugar, and backbone planning
Phosphorothioate and modified oligo support
GalNAc, peptide, lipid, dye, and antibody-oligo conjugation interface
Double-stranded oligo annealing and strand-ratio control
Purification, desalting, and lyophilisation
LC-MS, HPLC, CE, UV, residual solvent, water, and impurity analytics
Formulation and stability development
LNP, peptide conjugate, and sterile product interface
Spain and Switzerland-linked European technical execution
GMP/GMP-like documentation
Scale-up and tech transfer

The work is suited to products where sequence, chemistry, impurity control, formulation, and documentation all decide whether the programme can move forward.

FAQ: Oligonucleotide CDMO Services

1. What are Oligonucleotide CDMO Services?

Oligonucleotide CDMO Services support development and manufacturing of synthetic DNA or RNA products, including ASO, siRNA, aptamers, guide RNA, modified oligos, conjugated oligos, purification, analytics, formulation, stability, and documentation.

2. What types of oligonucleotides can Sophia support?

Sophia supports ASOs, siRNA, miRNA products, antagomirs, splice-switching oligos, exon-skipping oligos, aptamers, guide RNA, CpG oligos, GalNAc-conjugated oligos, peptide-conjugated oligos, diagnostic probes, and labelled oligos.

3. How are oligonucleotides manufactured?

Most synthetic oligonucleotides are manufactured using solid-phase phosphoramidite chemistry, followed by cleavage, deprotection, purification, desalting, analytical testing, formulation, and final drying or solution preparation.

4. What makes oligonucleotide manufacturing difficult?

Challenges include coupling efficiency, sequence length, modified nucleotides, deletion impurities, depurination, phosphorothioate complexity, purification, conjugation, residual reagents, impurity control, and stability.

5. What analytics are used for oligonucleotides?

Common analytics include LC-MS, ion-exchange HPLC, reverse-phase HPLC, capillary electrophoresis, UV spectroscopy, gel electrophoresis, Karl Fischer water testing, residual solvent testing, endotoxin where relevant, and stability-indicating methods.

6. Can Sophia support GalNAc-conjugated oligos?

Yes. Sophia supports GalNAc-conjugated oligonucleotide development through conjugation strategy, purification, identity testing, impurity profiling, formulation, stability, and documentation.

7. Can Sophia support double-stranded oligos such as siRNA?

Yes. Sophia supports strand synthesis, purification, annealing, duplex confirmation, strand-ratio control, conjugation, formulation, stability, and analytical development for siRNA and related duplex products.

8. Can oligonucleotides be lyophilised?

Yes. Many oligonucleotide products can be lyophilised when stability or shipping requires it. Lyophilisation must control reconstitution, residual moisture, purity, potency, and long-term stability.

9. What is the difference between ASO and siRNA manufacturing?

ASOs are usually single-stranded and may use gapmer or splice-switching designs. siRNA products are double-stranded and require separate strand control, annealing, duplex confirmation, and often delivery conjugation.

10. What should sponsors provide to begin an oligonucleotide project?

Useful starting information includes sequence, chemistry, modifications, conjugates, intended use, target purity, scale, existing synthesis data, analytical data, formulation needs, delivery route, stability goals, and regulatory stage.

Conclusion

Sophia provides the best oligonucleotide services for sponsors developing ASO, siRNA, miRNA, aptamer, guide RNA, CpG oligo, splice-switching, exon-skipping, conjugated oligonucleotide, diagnostic oligo, and advanced nucleic acid programmes.

Oligonucleotides are powerful because they act through sequence, structure, and chemical design. They can silence genes, alter splicing, guide editing systems, bind targets, stimulate immune pathways, or support diagnostics. They are difficult because each sequence must be manufactured with controlled chemistry, impurity profile, identity, purification, conjugation, formulation, stability, and documentation.

For sponsors developing antisense oligonucleotides, siRNA, GalNAc-conjugated oligos, aptamers, guide RNA, diagnostic probes, peptide-oligo conjugates, or next-generation nucleic acid medicines, Sophia provides a controlled route from sequence to stable, documented oligonucleotide product.

Email our team at info@sophiacdmo.com