TCO-PEG18 NHS Ester

TCO-PEG18 NHS Ester is a trans-cyclooctene (TCO)-functionalized, polyethylene glycol (PEG) linker reagent designed for efficient bioconjugation via NHS ester chemistry. As a click chemistry handle, TCO enables rapid, selective tetrazine-based ligation (commonly used in pretargeting workflows and signal amplification strategies), while the PEG spacer improves conjugation accessibility and reduces steric effects on biomolecules. This reagent is widely used to install TCO moieties onto amine-containing targets such as proteins, antibodies, peptides, and polymeric scaffolds for downstream click labeling, imaging, and materials functionalization.

1. Antibody And Protein Labeling

TCO-PEG18 NHS Ester is routinely used to functionalize antibodies and other amine-bearing proteins with TCO groups, generating click-ready bioconjugates for tetrazine-mediated tagging. The NHS ester reacts under standard bioconjugation conditions with lysine residues or N-termini, while the PEG18 spacer helps maintain binding-site accessibility and promotes uniform presentation of the TCO handle. Researchers use the resulting TCO-modified proteins as versatile intermediates for follow-on conjugation to imaging agents, affinity tags, or reporter constructs through tetrazine click chemistry.

2. Molecular Imaging Probes

TCO-PEG18 NHS Ester supports the preparation of imaging and detection probes that rely on tetrazine ligation for fast, selective assembly. By introducing TCO onto targeting biomolecules or probe scaffolds, the reagent enables modular workflows in which the TCO-bearing component can be combined with tetrazine-functional reporters to generate final imaging constructs under mild conditions. The PEG spacer is particularly valuable when attaching TCO to large biomolecular carriers, helping to reduce steric hindrance that can otherwise limit labeling efficiency and reproducibility across probe batches.

3. Diagnostic Reagent Development

TCO-PEG18 NHS Ester is used in the development of diagnostic and analytical reagents that benefit from orthogonal, high-selectivity click conjugation. TCO-functionalized capture reagents, affinity binders, or assay components can be prepared by NHS ester coupling to amine groups, then assembled with tetrazine-labeled detection elements to produce click-assembled assay formats. This approach is commonly favored in research reagent pipelines because it enables flexible pairing of TCO-bearing and tetrazine-bearing components, supporting streamlined optimization of assay architectures and signal readouts.

4. Biomaterials Surface Functionalization

TCO-PEG18 NHS Ester is applied to functionalize biomaterial surfaces and polymeric materials with TCO handles for subsequent tetrazine-based coupling. The NHS ester group allows attachment to amine-containing coatings, hydrogel components, or surface-modified polymers, while the PEG18 spacer improves handle accessibility on complex, heterogeneous substrates. Such TCO-functionalized materials are used as platforms for modular attachment of fluorescent reporters, affinity ligands, or other functional molecules via click chemistry, enabling robust surface engineering for research-grade material studies.