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Reactive functional groups for precise attachment of fluorophores, peptides, proteins, antibodies, GalNAc, lipids, polymers, nanoparticles, surfaces, and other payloads.
Conjugation handle modifications introduce reactive functional groups into an oligonucleotide to create a controlled attachment point for downstream bioconjugation. These handles allow DNA, RNA, siRNA, ASOs, aptamers, PNA, and other oligonucleotide formats to be linked to fluorophores, peptides, proteins, antibodies, GalNAc, lipids, polymers, nanoparticles, surfaces, and therapeutic delivery systems.
Bio-Synthesis offers a broad portfolio of functional groups for conjugation, including click chemistry modifiers, amino modifiers, thiol modifiers, carbonyl-reactive groups, carboxyl modifiers, multifunctional handles, bioorthogonal handles, and custom functional group designs. Handles may be incorporated at the 5' end, 3' end, or internal positions depending on the design and chemistry.
Select the functional group based on the reactive chemistry of the dye, peptide, protein, ligand, surface, polymer, or particle you want to attach.
Functional groups for oligonucleotide conjugation, labeling, immobilization, bioorthogonal ligation, and custom bioconjugation design.
Choose the reactive handle first, then tune position, spacer length, purification, and analytical QC to support reliable downstream conjugation.
Click, amino, thiol, carbonyl, carboxyl, multifunctional, and bioorthogonal handle families.
5′, 3′, or internal placement for terminal conjugation, spatial control, or surface display.
Spacer length can improve accessibility, reduce steric effects, and support conjugation efficiency.
Project-appropriate purification and analytical review for modified or conjugation-ready oligos.
Select handle
Choose position
Match payload chemistry
Define purification
Confirm QC needs
Click a conjugation handle category to review typical functional groups, common reactions, and applications. This is the main decision point for choosing an oligo modification for downstream conjugation.
Best for: selective bioorthogonal conjugation when the oligo must be linked to dyes, peptides, antibodies, GalNAc, polymers, nanoparticles, or other payloads after synthesis.
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Best for: NHS ester coupling, activated ester chemistry, isothiocyanate labeling, and broad attachment to dyes, biotin, surfaces, proteins, and particles.
Best for: maleimide coupling, disulfide chemistry, gold surface attachment, nanoparticle functionalization, and thiol-reactive conjugation workflows.
Best for: oxime ligation, hydrazone formation, and site-specific conjugation designs involving aldehyde, ketone, hydrazide, or aminooxy chemistry.
Best for: oligos requiring more than one function, such as a targeting ligand plus dye, a capture group plus reactive handle, or orthogonal handles for stepwise conjugation.
Best for: EDC chemistry, NHS activation, amide bond formation, surface coupling, and attachment to amine-containing partners.
Best for: highly selective ligation strategies that minimize interference with biomolecules, complex samples, or sensitive payloads. Useful when fast, orthogonal, or copper-free conjugation is preferred.
Bio-Synthesis can develop custom linkers, PEG spacers, multifunctional oligonucleotide designs, customer-supplied phosphoramidites, and novel conjugation chemistries for specialized research, diagnostic, and therapeutic applications.
Use this quick guide to match the reactive chemistry of your payload or conjugation partner with the appropriate oligonucleotide functional group. This reference helps identify the recommended conjugation handle for common bioconjugation workflows.
Broad support for standard and specialized reactive functional groups for conjugation-ready oligonucleotides.
Functional groups can be designed for 5', 3', or internal placement depending on chemistry and application.
Support for custom linkers, spacers, multifunctional handles, and customer-supplied building blocks.
Assistance with handle selection, linker strategy, purification, scale, and downstream conjugation planning.
Explore each chemistry family to learn about available modifications, conjugation strategies, design considerations, purification options, and application-specific recommendations.
Click-ready handles for bioorthogonal conjugation.
Primary amine functional groups for NHS ester chemistry.
Sulfhydryl modifications for maleimide and PEG conjugation.
Carbonyl-reactive handles for oxime and hydrazone ligation.
Carboxyl functional groups for EDC/NHS coupling.
Dual and multifunctional conjugation handle designs.
Advanced copper-free and orthogonal conjugation chemistries.
Complete custom oligonucleotide conjugation services.
Functional group compatibility, 5′ / 3′ / internal placement, linker spacing, conjugation chemistry, purification strategy, QC needs, and custom handle feasibility.
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