TCO-PEG2-Sulfo-NHS ester | CAS 2353409-48-8

TCO-PEG2-Sulfo-NHS ester is a strained-alkene trans-cyclooctene (TCO) click chemistry reagent presented as an NHS ester for efficient coupling to primary amines on biomolecules and surfaces. The PEG2 spacer improves aqueous handling and spacing between the reactive handle and the target, while the sulfonate provides strong water solubility and reduces nonspecific hydrophobic interactions. This reagent is widely used to install TCO moieties that serve as high-reactivity partners for subsequent bioorthogonal tetrazine ligation, enabling modular labeling, imaging probe assembly, and surface functionalization in chemical biology workflows.

1. Antibody And Protein Labeling

TCO-PEG2-Sulfo-NHS ester is commonly used to introduce TCO handles onto antibodies, enzymes, and other amine-containing proteins for downstream tetrazine-based conjugation. The NHS ester chemistry supports straightforward attachment to lysine residues under standard bioconjugation conditions, and the PEG2 spacer helps maintain favorable accessibility of the TCO group for efficient secondary coupling. The sulfonate functionality supports aqueous compatibility for probe generation and conjugate library workflows where consistent solubility and reduced aggregation are important.

2. Cell Surface And Biomaterial Functionalization

TCO-PEG2-Sulfo-NHS ester is used to functionalize cell-compatible materials and engineered surfaces that present accessible primary amines, including amine-derivatized hydrogels, polymer coatings, and porous scaffolds. By installing TCO groups at the material interface, researchers can subsequently attach tetrazine-bearing ligands, imaging agents, or capture moieties to create spatially defined functional surfaces. The PEG2 linker helps mitigate steric shielding at the surface, while the sulfonate improves handling in buffered aqueous environments typical for biomaterials characterization and surface chemistry studies.

3. Modular Imaging Probe Assembly

TCO-PEG2-Sulfo-NHS ester serves as a versatile intermediate for constructing tetrazine-reactive imaging probes and multicomponent molecular imaging reagents. After TCO installation on a targeting scaffold such as a protein, peptide, or polymer, tetrazine-functional imaging reporters can be coupled to generate conjugates with controlled stoichiometry and streamlined workflows. The water-soluble, PEG-spaced design supports reproducible conjugation in labeling pipelines where probe stability and reliable reactivity are critical for assay development and imaging reagent screening.

4. Diagnostic Reagent And Capture Conjugates

TCO-PEG2-Sulfo-NHS ester is frequently applied in the preparation of diagnostic reagent components that rely on modular assembly via tetrazine ligation. Amine-bearing recognition elements, such as affinity proteins and binding domains, can be TCO-functionalized to enable subsequent coupling with tetrazine-tagged reporters, beads, or assay-format capture reagents. The PEG2 spacer and sulfonate group support aqueous reagent formulation and help maintain accessibility of the click handle, supporting robust conjugate generation for analytical assay development and reagent optimization.