TCO-PEG2-TCO | CAS 2411687-18-6

TCO-PEG2-TCO is a bifunctional trans-cyclooctene (TCO) click chemistry reagent featuring a short polyethylene glycol (PEG) linker that spaces two reactive TCO groups for efficient engagement with tetrazine partners. As a strain-promoted inverse electron-demand Diels–Alder (IEDDA) click component, it is widely used in chemical biology and molecular imaging workflows where rapid, selective labeling is required under mild conditions. The PEG spacer supports solubility and reduces steric constraints, making TCO-PEG2-TCO a practical building block for constructing multivalent probes, conjugates, and imaging/diagnostic reagent platforms.

1. Multivalent Tetrazine Labeling

TCO-PEG2-TCO is used to generate multivalent labeling reagents that can bind and react with tetrazine-functionalized targets more effectively than monovalent TCO scaffolds. Researchers commonly employ it to build higher-avidity probe formats for cell-surface labeling, protein tagging, and assay reagents where improved signal generation depends on effective local concentration and conjugate architecture. The PEG2 linker helps maintain accessibility of both TCO handles, supporting robust conjugation design in complex labeling buffers.

2. Imaging Probe Conjugation

TCO-PEG2-TCO is frequently incorporated into molecular imaging and fluorescence-based probe development as a click handle for subsequent tetrazine-mediated conjugation to imaging reporters. In typical workflows, the reagent serves as a modular intermediate that can be attached to biomolecule carriers or targeting scaffolds, then coupled to tetrazine-functional dyes, nanoparticles, or other imaging moieties to produce well-defined imaging conjugates. The bifunctional nature enables construction of probe formats with controlled stoichiometry and flexible linker spacing between the targeting element and the reporter.

3. Biomaterial Surface Functionalization

TCO-PEG2-TCO is applied in biomaterials science to introduce reactive TCO groups onto polymeric or surface-supported platforms for downstream tetrazine click coupling. Materials teams use it to functionalize hydrogels, coatings, and scaffold surfaces where orthogonal, rapid labeling is advantageous for immobilizing fluorescent tags, affinity reagents, or other functional components. The PEG spacer supports aqueous compatibility and helps present the TCO groups away from the surface, improving accessibility for subsequent conjugation steps.

4. Diagnostic Reagent Building Blocks

TCO-PEG2-TCO is used as a click chemistry building block for assembling diagnostic reagent components that require modular coupling to tetrazine-bearing assay elements. Developers leverage its bifunctionality to create conjugate architectures for multiplexing strategies, standardized reagent preparation, and consistent coupling geometry between capture/recognition components and detection reporters. This design flexibility is particularly valuable when constructing complex assay reagents that benefit from controllable multivalent presentation and efficient conjugation under mild conditions.