TCO-PEG4-biotin | CAS 2183440-30-2

TCO-PEG4-biotin is a biotin-functionalized trans-cyclooctene (TCO) click chemistry reagent designed for strain-promoted inverse electron-demand cycloaddition (SPAAC) with tetrazines. The reagent couples a TCO handle to a flexible PEG4 spacer and a biotin affinity motif, enabling robust conjugation workflows that combine click labeling with downstream capture or enrichment. Its amphiphilic, linker-mediated design supports conjugation of biomolecules, probes, and materials while maintaining accessibility of both the tetrazine-reactive group and biotin for affinity-based handling.

1. Tetrazine-Tethered Imaging Probes

TCO-PEG4-biotin is widely used to prepare tetrazine-reactive imaging and tracking probes where a biotin handle is required for subsequent affinity capture, purification, or platform immobilization. Researchers in chemical biology and molecular imaging incorporate the reagent into probe architectures that are built around SPAAC labeling, then use biotin to route the resulting conjugates to streptavidin-coated surfaces, beads, or sensor formats. The PEG4 spacing helps maintain probe accessibility, which is particularly valuable when conjugates are assembled for microscopy, flow-based readouts, or surface-tethered imaging experiments.

2. Streptavidin-Based Pull-Down Workflows

TCO-PEG4-biotin supports affinity enrichment strategies that combine click chemistry with biotin-streptavidin binding. In proteomics, glycomics, and biomolecular interaction studies, the reagent is commonly used to introduce a TCO handle into labeling reagents or affinity probes, followed by SPAAC reaction with tetrazine-functional partners to generate biotin-bearing conjugates. The resulting products can then be efficiently captured using streptavidin resins or plates, enabling streamlined pull-down, washing, and downstream analytical workflows such as immunoblotting, mass spectrometry sample preparation, or targeted fractionation.

3. Surface Functionalization For Biosensing

TCO-PEG4-biotin is used to functionalize biosensor and diagnostic reagent surfaces where controlled immobilization of reactive biomolecular components is required. Many platform developers prepare tetrazine-modified surfaces or coatings and then use TCO-PEG4-biotin to attach biotin-tagged ligands, reporters, or binding elements through SPAAC, yielding stable surface conjugates that can be further organized via biotin-streptavidin coupling. The PEG4 linker improves surface accessibility and reduces steric hindrance, which is important for maintaining binding site availability in microarray formats, flow-cell assays, and other affinity-based detection platforms.

4. Multivalent Biomaterial Conjugates

TCO-PEG4-biotin is a practical building block for creating multivalent biomaterial conjugates and reagent scaffolds that require both click-reactivity and affinity functionality. Biomaterials and materials chemistry groups use the reagent to incorporate TCO moieties into PEGylated or biotinylated polymer constructs, hydrogel components, or nanoparticle surfaces, enabling SPAAC assembly with tetrazine-bearing crosslinkers, reporters, or targeting ligands. The combination of a flexible PEG4 spacer and biotin allows modular downstream processing, such as sequential conjugation steps, affinity-driven assembly, and standardized immobilization onto streptavidin-coated supports for research tool development and platform prototyping.