TCO-PEG8-TCO | CAS 2353409-67-1

TCO-PEG8-TCO is a bifunctional, polyethylene glycol–spaced trans-cyclooctene (TCO) click chemistry reagent designed for strain-promoted inverse electron-demand Diels–Alder (SPIED-ALD) reactions with tetrazines. The molecule features two TCO handles separated by a flexible PEG8 linker, enabling efficient multivalent conjugation and crosslinking in biomolecular labeling workflows. Its PEG-based architecture and dual-reactivity make it particularly relevant for building stable conjugates for imaging, diagnostics research, and modular probe development where controlled spacing and high labeling efficiency are important.

1. Tetrazine Probe Conjugation

TCO-PEG8-TCO is widely used to connect tetrazine-bearing targeting ligands, reporter moieties, or affinity reagents to create modular click conjugates with defined linker length. The dual TCO functionality supports multivalent labeling strategies that can improve probe brightness in assay formats by increasing the number of reactive attachment points per construct. Researchers commonly employ this reagent to generate conjugates for fluorescence, luminescence, and other label-based readouts, where PEG spacing helps maintain accessibility of binding domains and reduces steric constraints during probe assembly.

2. Multivalent Crosslinking Platforms

TCO-PEG8-TCO is well suited for constructing multivalent materials and reagent scaffolds through tetrazine-mediated crosslinking, including polymer networks, bead-based capture systems, and surface-tethered architectures. The presence of two TCO groups enables formation of higher-order linkages rather than simple one-to-one conjugation, supporting avidity-driven assembly of complex structures used in chemical biology and materials research. The PEG8 linker further contributes to flexibility, which is often leveraged to promote productive interactions between conjugated components while maintaining manageable mechanical and diffusion properties in assembled platforms.

3. Molecular Imaging Reagent Building

TCO-PEG8-TCO is used in molecular imaging reagent development to rapidly assemble tetrazine-functional imaging agents with controlled spatial separation between reactive sites and imaging labels. Dual TCO groups allow incorporation of multiple imaging or chelating elements into a single construct, supporting the preparation of well-defined probe families for method development in imaging chemistry. In practice, the reagent is commonly selected when researchers need a flexible linker that can reduce nonspecific steric effects and improve labeling consistency across batches of tetrazine-tagged components.

4. Biomaterials Surface Functionalization

TCO-PEG8-TCO supports click-based functionalization of biomaterials and research surfaces where tetrazine-containing coatings, linkers, or capture ligands are used to create robust, covalently assembled interfaces. The bifunctional design enables surface crosslinking or tethering strategies that can generate stable, spatially organized ligand presentations on hydrogels, polymer films, and bead surfaces. PEG8 spacing is particularly valuable in these workflows because it can help preserve ligand accessibility after immobilization, which is important for downstream assay development, binding studies, and analytical reagent optimization.