TCO-NHS ester

Trans-Cyclooctene (TCO)-NHS ester is an amine-reactive building block used to derivatize primary amine-containing molecules with a TCO moiety.


  • Biocompatible – click reaction occurs efficiently under mild buffer conditions; requires no accessory reagents such as a copper catalyst or reducing agents (e.g. DTT)
  • Primary amine reactivity – modify amine-containing molecules with TCO moiety for use in advanced crosslinking experiments
  • Unprecedented kinetics – inverse-electron demand Diels-Alder chemistry is the fastest bioorthogonal ligation available, delivering conjugates within 30 min at 1 mg/mL concentrations
  • Highly stable – TCO functional group remains stable in aqueous buffered media (weeks at 4C, pH 7.5)

TCO-NHS ester reacts specifically and efficiently with a primary amine (e.g., side chain of lysine residues or aminosilane-coated surfaces) at pH 7-9 to form a covalent bond. Short spacer arm adds minimal mass to modified molecules (153.2 daltons).

Catalog Number Product Size AVAILABILITY Price Qty
TCO-NHS ester, 25 mg
25mg In stock
Regular Price:$145.00
TCO-NHS ester, 100 mg
100mg In stock
Regular Price:$435.00
TCO-NHS ester, 1000 mg
1000mg In stock
Regular Price:$1,950.00

Product Type: Small Molecule
Name: Trans-Cyclooctene (TCO)-NHS Ester
Chemical Formula: C13H17NO5
Molecular Weight: 267.28
Variant MPN: 1016-25
Purity: >90% H NMR
Solubility: DCM, Chloroform, DMSO, DMF
Storage: Upon receipt store at -20C
Shipped: Ambient temperature


Applications: Protein-protein conjugation, protein-antibody conjugation, protein-small molecule conjugation, 18F radiolabeling, protein-oligonucleotide conjugation, surface modification

  1. Karver, M. R., et. al. (2012). "Bioorthogonal Reaction Pairs Enable Simultaneous, Selective, Multi-Target Imaging." Angew. Chem. Int. Ed., 51:920-922.
  2. Blackman, M. L., et. al. (2008). "Tetrazine Ligation: Fast Bioconjugation Based on Inverse- Electron-Demand Diels-Alder Reactivity." J. Am. Chem. Soc., 130:13518-13519
  3. Devaraj, N. K., et. al. (2008) "Tetrazine-Based Cycloadditions: Application to Pretargeted Live Cell Imaging." Bioconjugate Chem.,19(12): 2297–2299.
  4. Devaraj, N. K., et. al. (2009) "Fast and Sensitive Pre-Targeted Labeling of Cancer Cells through a Tetrazine/trans-Cyclooctene Cycloaddition." Angew. Chem. Int. Ed., DOI: 10.1002/anie.200903233
  5. Haun, J.B., et. al. (2009) " Probing Intracellular Biomarkers and Mediators of Cell Activation Using Nanosensor and Bioorthogonal Chemistry" ACS Nano., 5:3204-321
  6. Brand C, Iacono P, Pérez-Medina C, Mulder WJM, Kircher MF, Reiner T. Specific Binding of Liposomal Nanoparticles through Inverse Electron-Demand Diels-Alder Click Chemistry. ChemistryOpen. 2017 Aug 7;6(5):615-619. View Article

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