Thiol Modifiers

Thiol modifiers are a common type of chemical modification of synthetic oligonucleotides (oligos). Thiol modifiers are designed for use in DNA synthesizers to functionalize custom synthesized target oligonucleotides. BOC RNA offers a variety of thiol modifiers for custom oligonucleotide modification. Our experienced team will meet every specific requirement and expectation of our clients to facilitate their project development.


  • Sulfhydryl Group

Sulfhydryl group is also called mercapto group or thiol. It is a negative monovalent functional group composed of a sulfur atom and a hydrogen atom, and its chemical formula is -SH. Different groups are connected to the thiol end, and the organic compounds belong to different categories, such as thiol (R-SH) and thiophenol (Ar-SH). Two sulfhydryl groups are oxidized and dehydrated to form a disulfide bond (-S-S-). Sulfhydryl groups are essential for the active sites of many proteins and enzymes, and is easily oxidized to form intramolecular or intermolecular disulfide bonds, resulting in the loss of enzyme activity.

  • Thiol Modifier

Thiol modifiers are similar to amino modifications in many ways. Thiol modifiers are capable of covalently linking oligonucleotides to various biomolecules, such as ligands, peptides or proteins, and solid supports during or after solid phase synthesis of DNA or RNA oligonucleotides. The thiol modifier can be placed at the 5' end or 3' end of the oligonucleotide. Thiol modifiers are useful functional groups that form reversible disulfide bonds or irreversible sulfide bonds, which open the possibility of specific conjugation to sulfhydryl-containing ligands by forming disulfide bonds.

Thiol reacts with maleimide.Fig. 1 Thiol reacts with maleimide. (Leiro, 2018)

Types Of Thiol Modifiers Provided By BOC RNA

  • 5'-thiol modifiers

The 5' thiol modification is mainly used to modify the monomer with 5' thiol group (5'-Thiol-Modifier C6-CE Phosphoramidite or the Thiol-Modifier C6 S-S CE Phosphoramidite). The modification with 5'-Thiol-Modifier C6-CE monomer must be followed by silver nitrate oxidation to remove the protecting group (trityl), while the Thiol-Modifier C6 S-S CE monomer must be modified by DTT to reduce the disulfide bond to a sulfhydryl group.

  • 3'-thiol modifiers

3'-thiol modifier C3 S-S CPG is commonly used for the introduction of a thiol group to the 3'-terminal of the target oligonucleotide.

  • Thioctic acid derivatives

Dithiols or polysulfides provide a higher level of stability and are therefore well suited for the modification of gold nanoparticles or surfaces.

  • Internal thiol modifiers

Deoxythymidine (dT) modified with spacer groups and thiol groups can be used to add internal thiol modification groups at desired positions in the oligonucleotide sequence.

Thiol ModifiersPrice
5' Thiol-Modifier C6Inquiry
3' Thiol C3 SSInquiry
Thiol-Modifier C6 SSInquiry
Dithiol SS (DTPA)Inquiry

Application of thiol modified oligonucleotides

  • Linkage of oligonucleotides to gold surfaces
  • labeling with thiol-specific tags, such as iodoacetamide and maleimide
  • A combination of enzymes, especially horseradish peroxidase

BOC RNA is committed to meeting every specific requirement and expectation of our customers in order to be a trusted solution provider. Our advanced technology and experienced staff are dedicated to advancing our customers' project development. Based on our rich experience in the synthesis of thiolated oligonucleotides, we have the flexibility to design projects and customize solutions according to customer requirements. If you have any special requirements for thiol-modified oligonucleotide synthesis, please feel free to contact us.


  1. Leiro V; et al. Conjugation chemistry principles and surface functionalization of nanomaterials[M]//Biomedical applications of functionalized nanomaterials. Elsevier. 2018: 35-66.
* Only for research. Not suitable for any diagnostic or therapeutic use.
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