endo-BCN-PEG3-NH-Boc | CAS 1807501-84-3

endo-BCN-PEG3-NH-Boc is a BCN-based strained-alkyne reagent designed for copper-free click chemistry with tetrazines, enabling fast bioorthogonal conjugation in complex chemical and biological environments. The molecule incorporates an endo-oriented bicyclononyne (BCN) handle for reactivity in inverse-electron-demand tetrazine ligation, while the PEG3 spacer improves aqueous compatibility and reduces steric constraints during labeling. The terminal NH-Boc functionality provides a protected amine motif that can be carried through labeling workflows and subsequently deprotected or transformed for downstream coupling, making the reagent useful for constructing modular conjugates, imaging probes, and functional biomaterials.

1. Tetrazine Probe Labeling

endo-BCN-PEG3-NH-Boc is commonly used to install BCN tags onto biomolecules, polymers, or surfaces that will later be coupled to tetrazine-bearing reporters. Researchers value the reagent for creating stable, well-defined conjugation handles in labeling workflows where copper-free conditions are preferred, such as when working with sensitive proteins, enzyme systems, or multi-component assay mixtures. The PEG3 spacer supports efficient conjugation by improving solubility and accessibility of the BCN moiety, which is particularly helpful when labeling bulky targets like antibodies, affinity ligands, or carbohydrate-decorated constructs. The Boc-protected amine can also serve as a latent functional group for subsequent derivatization, enabling probe families that differ in charge, linker length, or secondary coupling chemistry.

2. Surface And Material Functionalization

endo-BCN-PEG3-NH-Boc supports BCN-mediated functionalization of material platforms that are subsequently addressed with tetrazine-functional components. In biomaterials research, the reagent is used to introduce click-ready reactive sites onto PEGylated coatings, hydrogel networks, and polymer brushes, allowing later attachment of fluorescent dyes, affinity tags, or imaging moieties without exposing the material to harsh conditions. The PEG3 chain helps the BCN group remain accessible at interfaces, improving labeling uniformity on heterogeneous substrates such as nanoparticle coatings or porous scaffolds. The protected amine handle provides a protected branching point for further surface chemistry steps, including controlled linker elaboration or coupling to additional functional groups after the initial tetrazine ligation.

3. Bioconjugation Linker Engineering

endo-BCN-PEG3-NH-Boc is widely applied as a modular bioconjugation reagent to engineer linker architectures between targeting units and downstream functional reporters. The BCN functionality enables orthogonal conjugation to tetrazine partners, which is advantageous when building multi-step constructs where pre-functionalization and later “on-demand” assembly are required. The PEG3 spacer is particularly relevant for reducing steric shielding around the reactive site, improving conjugation outcomes for large biomolecular conjugates and reducing nonspecific interactions in aqueous labeling buffers. After conjugation, the Boc-protected amine can be used as a controllable handle for subsequent derivatization, supporting workflows that generate libraries of conjugates with different secondary chemistry while maintaining a consistent clickable core.

4. Molecular Imaging And Diagnostics Reagents

endo-BCN-PEG3-NH-Boc is used in the development of molecular imaging and diagnostic reagent platforms that rely on tetrazine ligation for rapid assembly of labeled probes. Probe developers incorporate this BCN reagent to generate conjugates that can be matched with tetrazine-functional fluorophores, affinity reporters, or signal-generating tags, streamlining the preparation of imaging-ready constructs. The PEG3 spacer enhances water compatibility and helps preserve probe performance in labeling buffers, while the protected amine provides a convenient latent functionality for tailoring probe properties such as solubility, conjugation density, or attachment to secondary scaffolds. This makes endo-BCN-PEG3-NH-Boc a practical building block for constructing robust, modular probe designs used in analytical research workflows.