Oligo Nucleic Acid Bioconjugation
Oligo Nucleic Acid Bioconjugation

Nucleic Acid and Oligonucleotide Conjugates

Bio-Synthesis offers custom nucleic acid and oligonucleotide conjugate reagents as detection tools for DNA detection or as therapeutic agents. Our nucleic acid and oligonucleotide conjugation services offer chemical modification of nucleic acid at specific sites within individual nucleotides or within oligonucleotides. Which allows labels such as fluorescence, chemiluminescence or chromogenic enzyme substrates, as well as small and macromolecules to be incorporated into DNA, RNA or BNA probes or immobilized on the surface to facilitate diagnostic and targeted drug delivery.

Bio-Synthesis gives you the best quality in oligonucleotide conjugation chemistry by implementing a state-of-the art gene synthesis platform and expertise in providing high quality nucleic acid, oligonucleotide conjugates. Nucleic acid and oligonucleotide modification and conjugation services produced at Bio-Synthesis have substantial high purity. Bio-Synthesis is committed to Total Quality Management (TQM) to assure customers' complete satisfaction. Each oligo conjugate is meticulously monitored during synthesis and controlled according to the stringent quality assurance and quality control standards of Bio-Synthesis. The final product is identified by mass spectrum, while purity is analyzed by high throughput gel electrophoresis, analytical HPLC or any other appropriate QC methods. QA (quality assurance) procedures are also followed independently to double guarantee the high quality of every delivered peptide. Bio-Synthesis successfully upgraded the Total Quality Management System (TQM) to fully comply with ISO 9001:2008 regulations.

Custom Oligo Conjugation Services

Bio-Synthesis, the lead provider of oligonucleotide and gene synthesis since 1984, provides affordable custom nucleic acids, oligos or oligomimetic-biomolecule hybrid conjugates by providing our clients with comprehensive modifications and labeling to be used in biology, diagnostic and drug discovery.

We offer enzymatic labeling of DNA as well as chemical modification of nucleic acid and oligonucleotides. These chemically modified oligonucleotides are extremely useful in fixing conformations by introducing cross-linkers in DNA, RNA or nucleic acid-biomolecule complexes. Site-specific cross-linking permits the determination of the proximity of nucleotides or amino acids because the cross-linking would not be possible at distances greater than the length of the spacer. Such reagents are usually attached to either the base or the sugar moiety in most cases.

For the last two decades, we have accumulated a portfolio of oligonucleotide bioconjugates. Contact our National Customer Service Center at 800.227.0627 or contact us online with your detailed project descriptions.

Service Portfolios

  • Oligonucleotide-enzyme conjugates for diagnostic assay
  • DNA, small RNA, siRNA polyethylenimine (PEI) conjugates
  • Biotin-oligo labeling for immunoassay
  • Oligonucleotide-nanoparticle conjugates
  • RNA-antibody conjugates  for immunoassay
  • DNA-antibody conjugates for immuno PCR
  • DNA, RNA-Protein conjugates to study protein to protein interaction
  • siRNA-peptide conjugates for siRNA delivery
  • BNA-siRNA conjugates for therapeutic drug discovery
  • BNA-DNA conjugates for gene inhibition study
  • DNA-quantum dot conjugates for high sensitive detection application
  • DNA-KLH conjugates for antibody production
  • Oligonucleotide-agarose conjugates affinity chromatography immobilization
  • Oligonucleotide-drug conjugates for drug delivery
  • Conjugation of genomic DNA to antibody
  • Coupling of metal chelates onto recombinant proteins and antibodies (including the difficult IgMs) for radiolabeling
  • DNA-lipid conjugates for cellular uptake
  • Oligonucleotide-bead conjugates for luminex assay
  • DNA-glass plate conjugates for microarray detection
  • Nucleic acid photoreactive conjugates for nucleic acid-protein interaction
  • Polyethylenimine bioconjugates for imaging and DNA delivery in vivo
  • Antisense peptide nucleic acid for improving cellular uptake
  • Oligonucleotide-peptide conjugates for biomedical and technological applications
  • Nucleic acid-polymer hybrid conjugates for diagnostic and biomedicine

Oligonucleotide Conjugation Service Descriptions


Using preactivated small molecules and biomolecules with chemical reactive groups such as amine, thiol, carboxylate, hydroxyl, aldehyde and ketone, active hydrogen, photo-chemical to cross-link via zero-length, homobifunctional, heterobifunctional or multifunctional cross-linking chemistries, dendrimers, dendrons and cleavable regent systems.


After standard desalting, or purification, a small percent of heterogeneous products containing single or multi-site conjugate per molecule may exist.


  • Nucleic Acids and Oligonucleotides: DNA, RNA, siRNA, DNA mimetic, RNA mimetics
  • Biopolymers
    • Protein: Enzyme, antibodies, antigens, cell adhesion molecules
    • Peptides: Synthetic polypeptides
    • Saccharides:  Sugars, oligosaccharides and polysaccharides
    • Lipids:  Fatty acids, phospholipids, glycolipids and any fat-like substances.
    • Ligands:  Hormone receptors, cell surface receptors, avidin and biotin, small molecules
    • Labels: Fluorescent dyes, infrared-absorbing and UV-Vis absorption chromophores, nonradioactive labels
    • Nucleic acids and nucleotides: DNA, RNA, nucleic acid analogs and genomic DNA
    • Synthetic polymers: PEG, nanoparticles, gold particles, dendrimers, dendron, PAMAM
    • Others:  Conjugated or mixtures of any the above
    • Solid Supports: agarose, glass plates, membrane, beads


All custom synthesis of biomolecules, modification or bioconjugation services are manufactured under strict quality control processes. Analytical HPLC and MS analyses are performed in every development cycle. Final target conjugates must first be isolated from excess or unreacted reagent. In many cases, simple dialysis may suffice to remove unreacted reagent from the reaction solution.  Depending on the project scope, size-exclusion chromatography (SEC), HPLC,  may also be used to either remove excess reagent or isolate and characterized the cross-linked product. Cross-linked target molecule may then be further characterized by biochemical or biophysical techniques. Once the product has been purified, it may be subject to many different types of studies including spectroscopic (MALDI-TOF, ESI, LC-MS Fluorescence), electrophoresis, immunochemical biochemical, enzymatic analysis.  QC (quality control) and QA (quality assurance) procedures are also followed independently to offer you double guarantee for the highest quality possible of every delivered conjugates. Moreover, our dedicated technical account managers will guide your project through every step of the process and constantly keep you informed of the latest project progress.

Delivery Specifications:

The typical delivery consists of lyophilized sample in individual fully labeled vials. The shipment also contains COA, MS, HPLC and/or other analytical data.  Additional analytical data is also available upon request.

This service is for oligonucleotide bioconjugation using various types of cross-linking chemistries. If you can't find what you want? Please contact us online with your detail project descriptions.

Price: The price varies based on the project specifications. Our service includes materials and labor for conjugation only! Price does not include the cost of biopolymer synthesis and, if deemed necessary, biopolymer modification to introduce additional functional groups, extra linkers, spacers. Please contact us for a quote.

Ordering and Submitting Requests for Bioconjugation Services

For us to better understand your customized project, please complete our Bioconjugation Service Questionnaire. The more our chemists understand your project’s needs, the more accurate your provided feedback will be. Providing us with your project’s details enables us to recommend the best reagents to use for your project. The most useful and readily available tools for bioconjugation projects are cross-linking reagents. A large number of cross-linkers, also known as bifunctional reagents, have been developed. There are several ways to classify the cross-linkers, such as the type of reactive group, hydrophobicity or hydrophilicity and the length of the spacer between reactive groups. Other factors to consider are whether the two reactive groups are the same or different (i.e. heterobifunctional or homobifunctional reagents), spacer is cleavable and if reagents are membrane permeable or impermeable. The most accessible and abundant reactive groups in proteins are the ϵ-amino groups of lysine. Therefore, a large number of the most common cross-linkers are amino selective reagents, such as imidoesters, sulfo-N-hydroxysuccinimide esters and N-hydroxysuccinimide esters. Due to the high reactivity of the thiol group with N-ethylmaleimide, iodoacetate and a-halocarbonyl compounds, new cross-linkers have been developed containing maleimide and a-carbonyl moieties. Usually, N-alkylmaleimides are more stable than their N-aryl counterparts.

In addition to the reactive groups on the cross-linkers, a wide variety of connectors and spacer arms have also been developed. The nature and length of the spacer arm play an important role in the functionality. Longer spacer arms are generally more effective when coupling large proteins or those with sterically protected reactive side-chains. Other important considerations are the hydrophobicity, hydrophilicity and the conformational flexibility. Long aliphatic chains generally fold on themselves when in an aqueous environment, making the actual distance spanned by such linker arms less than expected. Instead, spacers containing more rigid structures (for example, aromatic groups or cycloalkanes) should be used. These structures, however, tend to be very hydrophobic which could significantly decrease the solubility of the modified molecules or even modify some of their properties. In such cases, it is recommended to choose a spacer that contains an alkyl ether (PEO) chain. Bio-Synthesis offers several cross-linkers with PEO chains, such as thiol-binding homobifunctional reagents, heterobifunctional bases and their derivatives.

Within 3-5 days upon receiving your project scope, we will provide you an appropriate quotation. An order can be placed with PO (Purchase Order) or major credit cards ( ). Your credit card will be billed under Bio-Synthesis, Inc.