TCO-PEG8-amine | CAS 2353409-92-2

TCO-PEG8-amine is a trans-cyclooctene (TCO) click chemistry reagent bearing an 8-carbon polyethylene glycol (PEG8) linker and a terminal primary amine. As a strained-alkene handle for fast tetrazine-mediated click reactions, it is widely used to install TCO moieties on biomolecules and materials while the PEG spacer improves solubility and reduces steric congestion during subsequent conjugation or labeling workflows. The presence of the amine enables straightforward coupling to activated carboxyl groups or other amine-reactive chemistries, making TCO-PEG8-amine a practical building block for preparing tetrazine-reactive probes, surfaces, and imaging reagents.

1. Tetrazine Probe Conjugation

TCO-PEG8-amine is commonly used to generate tetrazine-reactive labeling reagents for molecular imaging and chemical biology workflows, where TCO is reacted with tetrazines to form stable adducts under mild conditions. The PEG8 spacer helps maintain probe accessibility in aqueous buffers and on complex targets such as proteins, peptides, and polymeric carriers. Researchers frequently incorporate TCO-PEG8-amine as the TCO source during probe assembly, enabling subsequent one-step attachment of fluorophores, affinity tags, or reporter payloads through tetrazine click chemistry. The terminal amine also supports modular reagent design, allowing users to couple the TCO handle into carrier scaffolds prior to final labeling.

2. Protein and Peptide Labeling

TCO-PEG8-amine is a useful reagent for site-agnostic or scaffold-mediated conjugation strategies that introduce a TCO functionality onto proteins and peptides for downstream tetrazine click labeling. The amine group provides a convenient handle for linking the TCO-PEG8 motif to activated protein conjugation chemistries, including carboxyl-activated intermediates used in reagent kits and custom bioconjugation protocols. By using PEG8 as a spacer, conjugates often show improved handling in physiological-like buffers and better presentation of the strained alkene for efficient reaction with tetrazines. This makes TCO-PEG8-amine relevant for preparing research-grade protein probes, multivalent labeling constructs, and modular reagents used in target engagement studies and biochemical assays.

3. Surface Coating and Materials Functionalization

TCO-PEG8-amine is frequently applied to functionalize biomaterials and engineered surfaces with tetrazine-reactive groups for materials-based assays and platform development. The terminal amine enables attachment to a variety of substrate chemistries, including amine-reactive coatings and carboxyl-functional surfaces, allowing the TCO handle to be displayed at a controlled distance via the PEG8 linker. Once immobilized, the TCO-modified surfaces can be used to capture or pattern tetrazine-bearing reporters, enabling spatially resolved labeling and multistep assembly of diagnostic reagent components. This application is especially common in research settings where modular surface chemistry and rapid click-based coupling are required.

4. Multivalent Polymer and Nanocarrier Assembly

TCO-PEG8-amine supports the construction of multivalent polymer conjugates and nanocarrier systems that require a high density of tetrazine-reactive sites for robust downstream assembly. The PEG8 linker contributes to improved colloidal behavior and reduces non-specific interactions during formulation and handling, while the amine functionality allows incorporation into polymer backbones or carrier scaffolds through standard bioconjugation coupling routes. In practice, users employ TCO-PEG8-amine as a building block to create TCO-functional macromolecules that can later be decorated with tetrazine-linked imaging reporters, affinity ligands, or other functional modules. This approach is widely used in chemical biology and molecular imaging reagent development to create modular, tunable constructs for assay development and labeling workflows.