TCO-PEG3-NHS ester | CAS 2141981-88-4

TCO-PEG3-NHS ester is a trans-cyclooctene (TCO) functionalized NHS ester designed for efficient installation of a cyclooctene handle onto primary amines under standard bioconjugation conditions. As an amine-reactive click chemistry reagent, it is commonly used to prepare TCO-modified biomolecules, nanoparticles, and polymeric materials that subsequently participate in fast tetrazine–TCO ligation for labeling, imaging, and modular assembly. The PEG3 spacer supports improved solubility and reduces steric constraints, making the resulting TCO conjugates well suited for downstream bioconjugation workflows and reagent development.

1. Antibody And Protein Labeling

TCO-PEG3-NHS ester is widely used by antibody and protein engineering groups to introduce TCO moieties onto lysine residues via NHS ester chemistry, generating TCO-functional antibodies for subsequent tetrazine-based labeling. The PEG3 linker helps maintain accessibility of the TCO group, which is important when conjugates are used in flow cytometry sample prep, immunoassay reagent construction, or multiplexed probe generation. This reagent is also commonly selected for preparing TCO-modified enzymes and affinity proteins where robust, site-randomized amine labeling is sufficient to enable rapid downstream click labeling with tetrazine-bearing reporters.

2. Cell Surface And Receptor Probes

TCO-PEG3-NHS ester supports the preparation of TCO-decorated targeting ligands and receptor-binding proteins used in cell-based chemical biology experiments, including labeling of cell-surface components and visualization of binding interactions. By enabling amine-directed conjugation, researchers can generate TCO-tagged probes that are later coupled to tetrazine-functional dyes, affinity tags, or imaging handles under mild conditions compatible with sensitive biological reagents. The PEG3 spacer is particularly useful for maintaining probe performance in complex media by improving conjugate solubility and reducing steric hindrance around the cyclooctene reactive site.

3. Nanoparticle And Material Functionalization

TCO-PEG3-NHS ester is used to functionalize nanoparticles, surfaces, and polymeric materials that present accessible primary amines, allowing incorporation of TCO handles for subsequent modular assembly. In materials and molecular imaging development, TCO-functional nanocarriers are frequently prepared by conjugating TCO-PEG3-NHS to amine-containing coatings, dendrimers, or surface-modified carriers, enabling later attachment of tetrazine-bearing fluorophores, enrichment tags, or imaging reagents. This approach is valued for creating stable, modular platforms where the reactive TCO group can be introduced during material preparation and coupled to different reporters on demand.

4. Diagnostic Reagent And Assay Platforms

TCO-PEG3-NHS ester is commonly employed in the construction of diagnostic and analytical assay reagents that rely on tetrazine–TCO click coupling for rapid signal generation and modular reagent swapping. Assay developers use this NHS ester to create TCO-functional binding reagents, such as secondary binders or affinity components, that can be coupled to tetrazine-labeled detection components with controlled stoichiometry and streamlined workflows. The PEG3 spacer contributes to consistent accessibility of the reactive cyclooctene group, supporting reliable labeling performance when assembling multi-component assay systems and calibration reagents.