TCO-PEG6-NHS ester | CAS 2353409-96-6

TCO-PEG6-NHS ester is a trans-cyclooctene (TCO)–functionalized polyethylene glycol (PEG) linker bearing an N-hydroxysuccinimide (NHS) ester for efficient amide coupling to primary amines. As a click chemistry reagent, it is widely used in bioorthogonal trans-cyclooctene/tetrazine ligation to enable rapid labeling, conjugation, and modular assembly of functional biomolecules and materials. The PEG spacer and NHS handle support robust conjugation workflows to antibodies, proteins, peptides, and other amine-containing scaffolds, making it a common intermediate for downstream imaging and diagnostic-reagent development.

1. Antibody and Protein Labeling

TCO-PEG6-NHS ester is commonly used to introduce TCO moieties onto antibodies and other amine-rich proteins prior to tetrazine-mediated conjugation. The NHS ester reacts with lysine side-chain amines under standard bioconjugation conditions, generating stable amide linkages while the PEG6 spacer helps maintain accessibility of the TCO group for subsequent click ligation. This approach is frequently selected in research and industrial settings where modular preparation of TCO-tagged biorecognition reagents is needed for later pairing with tetrazine-functional imaging agents, affinity tags, or reporter constructs. The resulting conjugates are typically used to create well-defined labeling tools for molecular imaging experiments, assay development, and mechanistic studies that require high-efficiency, rapid secondary coupling.

2. Peptide Conjugation for Probes

TCO-PEG6-NHS ester supports site-agnostic but practical conjugation of TCO handles onto peptides and peptide-derived building blocks that contain accessible primary amines, enabling downstream assembly of click-ready probe candidates. PEGylation via the PEG6 linker can improve solubility and reduce steric constraints, which is advantageous when generating tetrazine-reactive probe formats for fluorescence, affinity, or mass-tagging workflows. Bioconjugation teams often rely on this reagent to convert peptide scaffolds into TCO-bearing intermediates that can be coupled to complementary tetrazine reagents in a controlled, modular manner. Such probe construction is widely used in chemical biology and molecular imaging research where researchers need a flexible pipeline to compare labeling density, linker length, and probe architecture without redesigning the core click chemistry functionality.

3. Surface and Material Functionalization

TCO-PEG6-NHS ester is frequently applied to functionalize amine-bearing surfaces and biomaterials, including polymeric matrices, hydrogel components, and protein-coated substrates, to create tetrazine-reactive interfaces. The NHS ester enables straightforward coupling to surface-exposed primary amines, while the PEG spacer provides a hydrated, flexible distance that can improve accessibility of the TCO group at the material interface. This makes the reagent useful for fabricating click-assembled coatings, immobilized capture platforms, and modular material conjugates where tetrazine-containing reporters or ligands are later attached through trans-cyclooctene/tetrazine ligation. In industrial chemical and biomaterials workflows, this strategy is often used to produce reproducible, scalable functional surfaces for research-grade diagnostic reagent development and analytical assay tooling.

4. Diagnostic Reagent and Assay Assembly

TCO-PEG6-NHS ester is used as a key intermediate for preparing TCO-functional components that can be rapidly assembled into diagnostic reagent formats using tetrazine click chemistry. Amine coupling via the NHS ester allows incorporation of TCO into assay-relevant proteins, linkers, or carrier constructs, which can then be conjugated to tetrazine-bearing reporters, labels, or capture elements under mild conditions. This modular assembly concept is particularly valued in assay development pipelines where multiple reagent variants must be generated efficiently from shared building blocks. Teams in chemical biology, molecular diagnostics research, and analytical reagent development commonly use TCO-PEG6-NHS ester to create standardized conjugation inputs that support consistent downstream labeling, multicomponent reagent construction, and workflow integration for platform-based assay prototyping.