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Custom Antisense Oligonucleotide (ASO) Synthesis Services

Custom ASO synthesis for three core product service platforms: Gapmer ASO, Steric-Blocking ASO, and Splice-Switching ASO. Bio-Synthesis supports advanced RNA modification strategies, scalable production, and rigorous quality control for research through GLP/GMP-aligned development workflows.

Gapmer ASO Steric-Blocking ASO Splice-Switching ASO 100 g/batch ISO 9001:2015 / ISO 13485:2016 45+ Years of Expertise U.S.A. Facilities - Texas GLP/GMP-Aligned

Custom ASO Synthesis Overview

Antisense oligonucleotide (ASO) synthesis enables precise, sequence-specific modulation of RNA for gene silencing, functional inhibition, and transcript engineering. ASOs are short, synthetic nucleic acid analogs designed to bind complementary RNA targets and control gene expression through multiple mechanisms, including RNase H-mediated degradation, steric blocking, and splice modulation.

Bio-Synthesis provides advanced custom ASO synthesis services supporting three core product platforms: Gapmer ASO, Steric-Blocking ASO, and Splice-Switching ASO. Each ASO can be fully customized using a broad range of base, sugar, backbone, linkage, terminal, and conjugation modifications, enabling optimized performance across research, translational, and therapeutic applications.

With over 45 years of oligonucleotide expertise, ISO-certified quality systems, and U.S.-based manufacturing facilities in Texas, Bio-Synthesis supports projects from early discovery through development-scale production, including custom synthesis up to 100 g/batch with GLP/GMP-aligned workflows.

Why Bio-Synthesis for ASO development?
  • Broad modification capability including thousands of standard, advanced, and exotic chemistries
  • Flexible ASO design across gapmer, steric-blocking, and splice-switching platforms
  • Integrated support from sequence design to synthesis, purification, QC, and conjugation
  • Scalable synthesis with high purity and rigorous analytical validation
  • Technical consultation for complex or specialized ASO workflows

Scale

From screening to larger development projects, Bio-Synthesis supports custom ASO synthesis up to 100 g/batch, depending on sequence, chemistry, purity, and documentation requirements.

Chemistry

Extensive modification capabilities across base, sugar, backbone, linkage, terminal, and conjugation chemistries, including thousands of standard and custom options.

Quality Control

Analytical validation options include LC-MS, HPLC, purity analysis, OD260 quantification, and custom release testing tailored to project requirements.

OEM & Development

ISO 9001:2015 / ISO 13485:2016 systems, GLP/GMP-aligned workflows, documentation support, tech transfer support, and U.S.-based manufacturing in Texas.

Core ASO Product Services

Gapmer ASO →

RNase H-mediated RNA knockdown

Gapmer ASOs use a central DNA gap flanked by chemically modified wings. After binding target RNA, the DNA/RNA duplex recruits RNase H1, resulting in targeted RNA cleavage.

  • mRNA knockdown and gene silencing
  • Target validation and functional genomics
  • Optimized gap-wing architecture

Steric-Blocking ASO →

Non-cleaving RNA functional inhibition

Steric-blocking ASOs bind RNA and physically interfere with translation, RNA-protein interactions, or regulatory RNA elements without recruiting RNase H.

  • Translation inhibition
  • miRNA inhibition / antimiR workflows
  • RNA-protein interaction blocking

Splice-Switching ASO →

Pre-mRNA splicing control

Splice-switching ASOs are specialized steric-blocking oligos that redirect splicing machinery to promote exon skipping, exon inclusion, or transcript isoform changes.

  • Exon skipping or exon inclusion
  • Transcript engineering
  • Precision RNA modulation

Antisense Oligonucleotide (ASO) Technology & Benefits

Antisense oligonucleotide (ASO) technology is a programmable RNA-targeting approach that uses short synthetic oligonucleotides to bind complementary RNA sequences and modulate gene expression. Depending on the ASO design, chemistry, and target site, ASOs can trigger RNA degradation, block RNA function, or redirect pre-mRNA splicing.

ASOs are especially useful because they can target both cytoplasmic and nuclear RNA, including mRNA, pre-mRNA splice sites, regulatory RNA elements, and selected noncoding RNAs. This makes ASOs a flexible platform for functional genomics, target validation, pathway analysis, and therapeutic oligonucleotide development.

ASO Technology Mechanisms & Benefits

Antisense oligonucleotide ASO mechanisms and benefits showing targeted RNA degradation, steric blocking, splice modulation, and miRNA inhibition

ASO mechanism overview. Antisense oligonucleotides support targeted RNA degradation, steric blocking, splice modulation, and miRNA inhibition through sequence-specific targeting and chemical modification strategies.

ASO design flexibility: By selecting the appropriate chemistry and architecture, antisense oligonucleotides can be optimized for RNA degradation, steric blocking, splice modulation, or regulatory RNA targeting—enabling precise control of gene expression across a wide range of applications.
Benefit How ASO Technology Helps Best-Fit Service
Programmable Specificity ASOs are designed by sequence, allowing direct targeting of selected RNA regions. Gapmer ASO, Steric-Blocking ASO, Splice-Switching ASO
Multiple Mechanisms The same oligonucleotide platform can support degradation, functional blocking, or splice modulation by changing design and chemistry. Mechanism-specific ASO synthesis
Nuclear RNA Access ASOs can target pre-mRNA and nuclear RNA regions, including splice junctions and regulatory elements. Splice-Switching ASO and steric-blocking designs
Chemical Optimization Backbone, sugar, base, linkage, terminal, and conjugation modifications can improve stability, affinity, potency, and delivery. Modified ASO synthesis and add-on services
Research to Development Scale Projects can move from discovery and screening quantities to larger qualified ASO batches depending on sequence, chemistry, QC, and documentation requirements. Custom ASO synthesis up to 100 g/batch
Custom optimization available: ASO performance can be tuned through sequence selection, gapmer architecture, wing chemistry, PS linkage strategy, splice-site targeting, purification grade, delivery conjugation, and custom QC requirements.

Oligonucleotide Modifications Used in ASO Design

Looking for a specific ASO modification?
The table below shows common ASO chemistries only. Bio-Synthesis supports thousands of advanced and exotic modifications across base, sugar, backbone, and linkage designs.

Contact us or request a quote for specialized ASO synthesis.

Modification Type Primary Function Best Use Key Advantage
Phosphorothioate (PS) Backbone stabilization and nuclease resistance Gapmer ASO, steric-blocking ASO, and SSO designs Improves oligo stability and supports in vivo-oriented ASO workflows
2′-O-Methyl (2′-OMe) RNA affinity and stability enhancement Steric-blocking ASO and splice-switching ASO Improves duplex stability while supporting non-cleaving mechanisms
2′-O-Methoxyethyl (2′-MOE) Higher binding affinity and improved pharmacokinetic properties Gapmer wings, steric-blocking ASO, and therapeutic-style ASO designs Widely used in advanced ASO designs requiring stability and potency
2′-Fluoro (2′-F) Affinity tuning and duplex stabilization Hybrid ASO designs and selected RNA-targeting applications Enhances binding strength and can be combined with other chemistries
LNA / BNA High-affinity binding and mismatch discrimination Gapmer wings, short ASOs, and high-specificity designs Enables stronger target binding with shorter oligo designs
cEt / Constrained Ethyl High-affinity wing chemistry Advanced gapmer and therapeutic-style ASO designs Supports potent RNA binding and durable activity in optimized designs
Morpholino / PMO Non-natural backbone for steric blocking Steric-blocking ASO and splice-switching ASO Does not activate RNase H and is well suited for splice modulation
Conjugates Delivery, targeting, or detection enhancement GalNAc, cholesterol, peptides, lipids, fluorophores, and biotin labeling Supports targeted delivery, tracking, purification, and functional assay needs
Need a modification not shown here?
The modifications listed above are only common examples. Bio-Synthesis supports thousands of exotic and custom base, sugar, backbone, and linkage modifications. If you do not see the exact modification you need, contact us or request a quote — our team can support highly specialized ASO designs.

Custom Synthesis Options

Bio-Synthesis offers flexible ASO synthesis tailored to research, translational, and development-stage projects.

Design & Chemistry

  • Custom sequence synthesis
  • Gapmer, steric-blocking, and splice-switching designs
  • Backbone, sugar, base, linkage, and terminal modifications
  • Standard and advanced modification patterns

Scale & Purification

  • Research to development-scale synthesis
  • Project support up to 100 g/batch
  • HPLC and PAGE purification options
  • Salt exchange, desalting, and lyophilization support

Quality Control

  • Mass spectrometry confirmation
  • Analytical HPLC
  • OD260 quantification
  • Custom release testing upon request

Quality System Support

  • ISO 9001:2015 / ISO 13485:2016
  • GLP/GMP-aligned project support
  • U.S.A. facilities in Texas
  • 45+ years of oligonucleotide expertise

Optional Add-On Services

Custom Formulation & Packaging →

Buffers (TE/PBS/custom), aliquoting, concentrations, tubes or plates, OEM labels/barcodes.

Custom Quality Control →

LC-MS, CE, extended HPLC traces, endotoxin/bioburden, water content, residual chemical analysis, stability program.

Regulatory & OEM →

RUO→GLP→cGMP pathways, document packages, tech transfer, sequence masking.

Contact & Quote Request

For the fastest review, send your target sequence, desired mechanism, ASO type, preferred modifications, scale, purification, QC requirements, and any delivery or conjugation needs.

Fast quote checklist

  • Target gene/transcript and species
  • Mechanism: knockdown, steric blocking, or splice switching
  • Desired modification pattern
  • Scale and purity requirements
  • QC, documentation, and add-on service needs

Fastest path

FAQ

What are the three main ASO product services?

The three core ASO services are Gapmer ASO, Steric-Blocking ASO, and Splice-Switching ASO.

What is the difference between gapmer and steric-blocking ASO?

Gapmers recruit RNase H1 to degrade RNA, while steric-blocking ASOs bind RNA without cleavage and block RNA function or interactions.

Are the listed modifications all Bio-Synthesis offers?

No. The table lists common examples only. Bio-Synthesis supports thousands of advanced base, sugar, backbone, and linkage modifications.

What scale can Bio-Synthesis support?

Projects can be supported from research scale through larger development needs, including up to 100 g/batch depending on sequence, chemistry, and project requirements.

Recommended Reading

Selected literature supporting ASO mechanisms, chemistry optimization, gapmer design, steric-blocking ASOs, and splice-switching oligonucleotide applications.

Why Choose Bio-Synthesis

Trusted by biotech leaders worldwide for over 45+ years of delivering high quality, fast and scalable synthetic biology solutions.