TCO-PEG9-maleimide | CAS 2183440-37-9

TCO-PEG9-maleimide is a PEGylated trans-cyclooctene (TCO) click chemistry reagent designed for strain-promoted inverse electron-demand cycloaddition with tetrazines, enabling rapid bioorthogonal conjugation under mild conditions. The molecule combines a TCO reactive handle with a maleimide group for efficient coupling to thiols, while the PEG9 spacer improves solubility and reduces steric effects during labeling. This reagent is widely used to prepare tetrazine-compatible imaging probes, targeted labeling reagents, and modular biomaterials that benefit from orthogonal, fast click conjugation workflows.

1. Thiol-Targeted Conjugation

TCO-PEG9-maleimide is commonly used to attach TCO functionality to thiol-bearing biomolecules such as cysteine- or thiol-derivatized peptides, proteins, and antibody fragments. The maleimide handle supports straightforward installation onto free sulfhydryls, yielding tetrazine-reactive conjugates that are then carried forward into downstream inverse electron-demand click labeling steps. The PEG9 spacer helps maintain reagent accessibility and improves handling in aqueous bioconjugation workflows, which is particularly valuable when preparing multivalent or sterically demanding constructs for research-scale probe development.

2. Molecular Imaging Probe Assembly

TCO-PEG9-maleimide is frequently selected for building modular imaging and detection reagents that rely on tetrazine-based click chemistry for signal generation or payload transfer. Researchers use the thiol-reactive maleimide to generate TCO-functional targeting or affinity components, which can subsequently be reacted with tetrazine-tagged fluorophores, radioisotope chelates, or other imaging moieties through rapid strain-promoted cycloaddition. This approach supports iterative probe design, where the same TCO-bearing scaffold can be paired with different tetrazine partners to tune imaging format, labeling density, and conjugate architecture for assay development and imaging reagent optimization.

3. Biomaterials Surface Functionalization

TCO-PEG9-maleimide is applied to functionalize biomaterial surfaces and polymeric scaffolds that present thiol groups, enabling the creation of tetrazine-reactive materials for spatially controlled labeling and modular assembly. In materials research, maleimide-mediated coupling is used to introduce TCO handles onto hydrogels, coatings, and functional polymers, after which tetrazine-functional components can be clicked onto the surface to generate defined composite materials, patterned interfaces, or multicomponent assemblies. The PEG spacer is particularly useful for maintaining accessibility of the cyclooctene moiety on crowded surfaces, supporting consistent conjugation in complex material environments.

4. Diagnostic Reagent Development

TCO-PEG9-maleimide is used in the development of diagnostic and analytical reagents that benefit from orthogonal, fast click conjugation between TCO and tetrazine partners. Teams in biochemical assay development often install TCO onto capture reagents, affinity ligands, or reporter scaffolds via the maleimide-thiol coupling step, then use tetrazine-containing detection components to generate final assay-ready conjugates. This two-stage design supports flexible reagent pairing and streamlined optimization of labeling stoichiometry, enabling robust workflows for constructing assay reagents used in research and industrial laboratory settings.