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Unsaturated Fatty Acid-Modified Oligonucleotides

Custom mono- and polyunsaturated fatty acid conjugation for DNA, RNA, ASO, siRNA, duplex RNA and specialty oligonucleotides, including oleic acid, linoleic acid, α-linolenic acid, arachidonic acid, EPA, DPA and DHA architectures with terminal, internal and multivalent design options.

MUFA & PUFA 5′ • 3′ • Internal Mono • Di • Multivalent siRNA • ASO • DNA • RNA Custom Conjugation

Unsaturation Adds a Second Design Variable Beyond Chain Length

Unsaturated fatty acid-modified oligonucleotides combine hydrophobic lipid character with one or more carbon-carbon double bonds. Compared with saturated analogs of similar chain length, unsaturation can alter chain flexibility, molecular packing, membrane interaction, protein association, self-assembly, chromatographic retention, and formulation behavior.

Bio-Synthesis can evaluate terminal, selected internal, mono-lipid, dual-lipid, and multivalent unsaturated fatty acid architectures. The final design should define fatty acid identity, double-bond pattern, position, linker, valency, oligonucleotide modality, and analytical strategy together.

Representative architecture: the DHA figure shows how one highly unsaturated lipid can be presented as mono-, di-, or multivalent oligonucleotide conjugates. DHA is an example; the page covers a broader MUFA and PUFA design space.

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Representative mono-, di- and multivalent DHA-oligonucleotide architectures

Chain Length

C14-C24 research-relevant unsaturated fatty acids provide a broad hydrophobic design space.

Degree of Unsaturation

One or multiple double bonds can substantially alter conformation and physicochemical behavior.

Placement

5′, 3′ and selected internal attachment can be evaluated through suitable conjugation or custom direct chemistry.

Valency

Single-, dual- and multivalent architectures allow systematic comparison of lipid number and presentation.

Compare MUFA and PUFA Conjugation Options

The library is organized by carbon number and degree of unsaturation. Exact cis/trans geometry, omega family, and double-bond position should be specified when they matter to the intended construct or study.

C14:1
Myristoleic Acid

Monounsaturated fatty acid

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C16:1
Palmitoleic Acid

Monounsaturated fatty acid

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C18:1
Oleic Acid

cis-C18:1; common MUFA reference

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C18:1
Vaccenic Acid

Positional C18:1 isomer

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C18:2
Linoleic Acid

n-6 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C18:3
α-Linolenic Acid (ALA)

n-3 PUFA

Post-Conjugation Omega-3

5′ • 3′ • selected internal

C18:3
γ-Linolenic Acid (GLA)

n-6 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C18:4
Stearidonic Acid (SDA)

n-3 PUFA

Post-Conjugation Omega-3

5′ • 3′ • selected internal

C20:1
Eicosenoic / Gondoic Acid

Monounsaturated C20 fatty acid

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C20:2
Eicosadienoic Acid

C20 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C20:3
Dihomo-γ-Linolenic Acid (DGLA)

n-6 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C20:3
Mead Acid

n-9 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C20:4
Arachidonic Acid (ARA)

n-6 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C20:5
Eicosapentaenoic Acid (EPA)

n-3 long-chain PUFA

Post-Conjugation Omega-3

5′ • 3′ • selected internal

C22:1
Erucic Acid

Very-long-chain MUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C22:4
Adrenic Acid

n-6 PUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

C22:5
Docosapentaenoic Acid (DPA)

n-3 or n-6 isomer should be specified

Post-Conjugation Omega-3 option

5′ • 3′ • selected internal

C22:6
Docosahexaenoic Acid (DHA)

n-3 highly unsaturated PUFA

Post-Conjugation Omega-3

5′ • 3′ • selected internal • multivalent

C24:1
Nervonic Acid

Very-long-chain MUFA

Post-Conjugation Custom Direct

5′ • 3′ • selected internal

Availability note: this is a research-relevant library, not a claim that every lipid exists as a routine off-the-shelf phosphoramidite. Post-conjugation is the broadest route; direct-incorporation chemistry is project specific unless a validated reagent is available.

Same Chain Length. Different Degree of Unsaturation.

Matched-chain lipid series can help separate the effect of carbon-chain length from the effect of double-bond number. C18 is a useful example because saturated and progressively unsaturated analogs can be compared within the same carbon count.

C18:0

Stearic Acid

○○○
C18:1

Oleic Acid

●○○
C18:2

Linoleic Acid

●●○
C18:3

ALA / GLA

●●●

Design use: a C18:0 → C18:1 → C18:2 → C18:3 series can be used to investigate how increasing unsaturation changes oligonucleotide conjugate behavior while keeping the overall carbon count similar.

Where Unsaturated Fatty Acid-Modified Oligonucleotides Are Used

RNAi

siRNA Delivery Research

Oleic, linoleic, ARA, EPA and DHA conjugates can be evaluated as hydrophobic siRNA architectures for cellular association, tissue-exposure and delivery research.

  • Passenger or guide strand
  • 5′, 3′ or internal placement
  • Mono- versus multivalent lipidation
Antisense

ASO & Gapmer Conjugation

Unsaturated fatty acids can be combined with antisense backbones to study protein association, cellular uptake, distribution and hydrophobicity.

  • PS and affinity-enhancing sugar designs
  • Terminal or selected internal conjugation
Membrane

Membrane Association & Surface Display

Unsaturated lipid anchors can be explored for membrane association, cell-surface presentation, and lipid-rich model systems.

  • DNA, RNA, aptamer or probe formats
  • Spacer-assisted presentation
SAR

Lipid Structure–Activity Relationships

Compare chain length, unsaturation, omega family, position and valency while keeping the oligonucleotide sequence fixed.

  • C18 matched-series studies
  • n-3 versus n-6 versus n-9
Imaging

Imaging & Localization Studies

Unsaturated fatty acids can be combined with fluorophores or reporters when linker and label placement are designed to minimize interference.

  • Membrane localization
  • Cell-association tracking
Assembly

Lipid Assembly & Formulation Research

Unsaturated lipid-oligo conjugates can be evaluated in lipid-rich assemblies, model nanoparticles or multicomponent delivery systems.

  • Surface presentation
  • Mono- and multivalent constructs

Build an Unsaturated Fatty Acid–Oligonucleotide SAR Series

Degree of Unsaturation

Keep carbon count similar while increasing double bonds.

C18:0 → C18:1 → C18:2 → C18:3

Chain Length

Hold unsaturation class relatively constant while changing lipid length.

C14:1 → C16:1 → C18:1 → C20:1 → C22:1 → C24:1

Omega Family

Compare biologically distinct unsaturated lipid families.

n-3 ↔ n-6 ↔ n-9

Position & Valency

Separate lipid identity from presentation on the oligonucleotide.

5′ → 3′ → internal • 1× → 2× → 3×+

How Unsaturated Fatty Acids Are Introduced

Post-Synthetic Conjugation

The oligonucleotide is first synthesized with a reactive handle and then coupled to an activated unsaturated fatty acid or lipid derivative.

Reactive Oligo + Activated Lipid Conjugate

Best fit: broad lipid screening, custom spacers, internal handles, and multivalent constructs.

Custom Direct-Incorporation Chemistry

A dedicated modifier or phosphoramidite may be developed when the desired linkage and position justify a direct solid-phase synthesis route.

Custom Modifier Solid-Phase Synthesis Defined Product

Best fit: repeated programs where the exact modifier architecture is already defined.

Branched / Multivalent Assembly

Multiple unsaturated fatty acid groups can be presented through branched scaffolds or orthogonal attachment handles.

Oligo Branch / Handles 2× / 3× Lipid

Watch: hydrophobicity, conversion, purification, aggregation and analytical homogeneity.

Unsaturated Fatty Acid Conjugation Across DNA and RNA Formats

Single-Stranded DNA

Terminal or selected internal unsaturated fatty acid conjugation for specialty DNA, probes and membrane-association studies.

Single-Stranded RNA

Terminal or selected internal lipidation with attention to deprotection, handling and oxidation-sensitive chemistry.

ASO / Gapmer

Unsaturated lipid conjugation can be coordinated with PS and affinity-enhancing sugar-modified antisense architectures.

siRNA / Duplex RNA

Evaluate strand, terminus, linker, valency and stabilization pattern together with lipid identity.

Aptamer

Hydrophobic anchors can support membrane association or formulation studies while preserving folding and binding.

Imaging Oligos

Lipid and fluorophore placement should be separated enough to reduce steric or optical interference.

Branched Oligos

Multiple attachment points enable comparative mono-, di- and multivalent unsaturated lipid architectures.

Custom Constructs

Customer-supplied lipids, defined isomers and multicomponent architectures can be reviewed for feasibility.

Omega-3 Fatty Acid–Oligonucleotide Conjugates

Omega-3 fatty acids form an important specialty subset of the unsaturated-fatty-acid platform. ALA, SDA, EPA, DPA and DHA differ in chain length and degree of unsaturation and can support distinct oligonucleotide conjugation studies.

ALA C18:3 n-3 SDA C18:4 n-3 EPA C20:5 n-3 DPA C22:5 n-3 DHA C22:6 n-3

Dedicated subpage planned: use the Omega-3 Oligonucleotide Conjugates page for deeper EPA/DPA/DHA application, stability, and design guidance.

Higher Unsaturation Requires Greater Attention to Oxidative Stability

Carbon-carbon double bonds increase susceptibility to oxidative degradation. This concern generally becomes more important as the number of double bonds increases, particularly for highly polyunsaturated EPA- and DHA-containing constructs.

Oleic

C18:1

Linoleic

C18:2

●●
ARA

C20:4

●●●●
EPA

C20:5

●●●●●
DHA

C22:6

●●●●●●

Oxygen & Light

Minimize unnecessary exposure during storage and handling, especially for highly polyunsaturated constructs.

Temperature

Low-temperature storage may be appropriate depending on formulation, sequence and final product format.

Purification

Unsaturated conjugates can show different chromatographic behavior from saturated analogs of similar chain length.

Analytical Monitoring

Mass and chromatographic profiles should be reviewed for the intended conjugate and degradation-related species when relevant.

Plan Release Around the Unsaturated Lipid Architecture

Identity

Expected molecular mass and conjugate assignment by an appropriate mass method.

Purity

RP-HPLC or other fit-for-purpose chromatography adapted to hydrophobicity and lipid structure.

Conjugation

Assessment of conversion and separation from unconjugated oligo or excess lipid-related species.

Stability

Project-specific attention to oxidative stability for highly unsaturated constructs.

Duplex

Annealing and duplex assessment for siRNA or other duplex RNA designs when required.

Design an Unsaturated Fatty Acid-Modified Oligonucleotide

Share your sequence, oligonucleotide type, fatty acid identity, double-bond specification, attachment position, linker, valency, scale, purification grade and analytical requirements. If the exact route is not yet defined, Bio-Synthesis can review post-conjugation or custom direct-incorporation options.

What to Specify

Lipid: Oleic, Linoleic, ALA, ARA, EPA, DPA, DHA, other
Isomer: cis/trans, n-3/n-6/n-9 where relevant
Position: 5′, 3′, internal
Valency: 1×, 2×, multivalent
Oligo: DNA, RNA, ASO, siRNA

Panel Development

Ask about matched lipid series by chain length, degree of unsaturation, omega family, attachment position or valency.

Controlled Support from Conjugation Through Release

QMS

ISO-Supported Unsaturated Fatty Acid-Oligonucleotide Manufacturing

Custom unsaturated fatty acid-modified oligonucleotides are supported by documented synthesis or conjugation, purification, analytical QC, traceability and project-specific handling from feasibility through repeat manufacturing.

ISO 9001:2015 Quality management system supporting documented synthesis, conjugation, purification, and release workflows.
ISO 13485:2016 Medical-device quality framework supporting controlled documentation and traceable manufacturing processes.
ISO 14001 Environmental management system supporting responsible laboratory and manufacturing operations.
Analytical QC HPLC/UPLC or fit-for-purpose chromatography, MS where compatible, OD, COA, and project-specific release testing.

Frequently Asked Questions

FAQ

How is an unsaturated fatty acid different from a saturated fatty acid on an oligonucleotide?
 Unsaturated fatty acids contain one or more carbon-carbon double bonds. These bonds change chain flexibility and packing and can influence membrane interaction, self-assembly, purification, formulation and oxidation sensitivity.
Can EPA and DHA be attached to siRNA?
 Yes, suitable terminal, selected internal, mono- or multivalent conjugation architectures can be evaluated. The preferred strand and position should be considered together with RNA stabilization, linker, duplex behavior and the intended study.
Are polyunsaturated fatty acid conjugates more oxidation-sensitive?
 In general, higher degrees of unsaturation require greater attention to oxidative stability. Storage, handling and analytical monitoring should be matched to the final conjugate and formulation.
Can multiple unsaturated fatty acids be attached to one oligonucleotide?
 Mono-, dual- and multivalent architectures can be evaluated where the scaffold, reactive handles, conjugation chemistry and purification strategy support the design.
Why compare C18:0, C18:1, C18:2 and C18:3?
 A matched C18 series can help evaluate the effect of increasing unsaturation while keeping the overall carbon count similar.
Does a more unsaturated lipid automatically improve delivery?
 No. Biological performance depends on the complete architecture, including lipid identity, double-bond pattern, linker, valency, position, sequence, backbone chemistry, nucleotide modifications and formulation.

Selected Literature on Fatty Acid & Lipid-Oligonucleotide Conjugation

These publications focus on hydrophobic and fatty-acid conjugation of siRNA and related oligonucleotide architectures, including DHA, EPA, saturated and unsaturated fatty acids, lipid valency, systemic distribution, and extrahepatic delivery.

  1. Wolfrum C, et al. Mechanisms and optimization of in vivo delivery of lipophilic siRNAs. Nature Biotechnology. 2007;25(10):1149-1157. Demonstrates that long-chain fatty-acid and other lipophilic siRNA conjugates can alter cellular uptake and in vivo delivery through lipid-transport pathways. PubMed →
  2. Osborn MF, et al. Hydrophobicity drives the systemic distribution of lipid-conjugated siRNAs via lipid transport pathways. Nucleic Acids Research. 2019;47(3):1070-1081. Examines how lipid structure and hydrophobicity influence lipoprotein association, pharmacokinetics, tissue accumulation, and functional silencing. PubMed →
  3. Biscans A, et al. Diverse lipid conjugates for functional extra-hepatic siRNA delivery in vivo. Nucleic Acids Research. 2019;47(3):1082-1096. Compares a broad panel of lipid-siRNA conjugates and demonstrates that conjugate chemistry can substantially change tissue distribution and productive silencing. PubMed →
  4. Biscans A, Coles A, Echeverria D, Khvorova A. The valency of fatty acid conjugates impacts siRNA pharmacokinetics, distribution, and efficacy in vivo. Journal of Controlled Release. 2019;302:116-125. Directly compares mono-, di-, and tri-fatty-acid conjugated siRNAs, including myristic acid, DHA, and EPA architectures. PubMed →
  5. Nikan M, et al. Docosahexaenoic Acid Conjugation Enhances Distribution and Safety of siRNA upon Local Administration in Mouse Brain. Molecular Therapy - Nucleic Acids. 2016. Provides a focused example of DHA directly conjugated to chemically modified siRNA for distribution and gene-silencing studies in brain tissue. PubMed →
  6. Biscans A, et al. The chemical structure and phosphorothioate content of hydrophobically modified siRNAs impact extrahepatic distribution and efficacy. Nucleic Acids Research. 2020;48(14):7665-7680. Highlights that lipid structure and oligonucleotide backbone chemistry should be optimized together rather than independently. PubMed →
  7. Yamada T, et al. Sixteen Different Types of Lipid-Conjugated siRNAs Containing Saturated and Unsaturated Fatty Acids and Exhibiting Enhanced RNAi Potency. ACS Chemical Biology. 2021. Compares siRNAs conjugated with a series of saturated and unsaturated fatty acids and evaluates hybridization, uptake, and RNAi activity. PubMed →
  8. Fatty acid-conjugated siRNA study. Direct Transfection of Fatty Acid Conjugated siRNAs and Knockdown of the Glucose-Regulated Chaperones in Prostate Cancer Cells. Bioconjugate Chemistry. 2018. Uses saturated and unsaturated fatty-acid bioconjugation across linear and branched RNA architectures for cellular uptake and knockdown studies. PubMed →

Scientific note: these studies illustrate design principles rather than a universal ranking of lipids. Unsaturated fatty acid identity, chain length, double-bond pattern, position, linker, valency, oligonucleotide chemistry, and route of administration can all influence the behavior of the final conjugate.

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