endo-BCN-PEG4-NHS ester | CAS 2252422-32-3

endo-BCN-PEG4-NHS ester is a BCN-based click chemistry reagent designed for strain-promoted azide–alkyne cycloaddition (SPAAC) with azide partners under copper-free conditions. The molecule couples a bicyclononyne (BCN) cyclooctyne handle to a PEG4 spacer and an NHS ester for efficient reaction with primary amines on biomolecules and surfaces. This combination makes it a widely used intermediate for preparing azide-free BCN conjugates that can later be clicked onto azide-functional targets in labeling, materials, and imaging workflows.

1. Amine-Target Bioconjugation

endo-BCN-PEG4-NHS ester is commonly used to functionalize proteins, peptides, and antibody fragments by reacting its NHS ester with accessible primary amines, generating stable BCN-bearing conjugates for subsequent copper-free click labeling. The PEG4 spacer helps maintain conjugate solubility and reduces steric constraints, which is particularly valuable when preparing probe libraries, affinity reagents, or multivalent labeling constructs. Researchers frequently choose this format when they need a robust way to install a SPAAC-compatible BCN handle onto an amine-rich biomolecule without introducing azide groups during the initial conjugation step.

2. Surface And Material Functionalization

endo-BCN-PEG4-NHS ester is also applied to modify amine-containing surfaces and biomaterials, including polymeric scaffolds, hydrogel networks, and functionalized beads, where NHS chemistry enables attachment to surface-exposed lysines or amine-terminated groups. After immobilization, the BCN moieties provide a convenient handle for later SPAAC coupling to azide-functional dyes, ligands, or imaging tags. This approach is widely used in materials science and chemical biology for building clickable coatings, creating modular diagnostic reagent platforms, and preparing spatially addressable or batch-processed surfaces for downstream conjugation.

3. Molecular Imaging Probe Building

endo-BCN-PEG4-NHS ester is frequently used as a precursor for assembling imaging and detection probes that rely on SPAAC to connect a BCN-bearing targeting component to an azide-functional reporter. By first installing BCN onto an amine-containing targeting scaffold (such as a protein, peptide, or nanoparticle surface) through the NHS ester, probe developers can then perform a controlled secondary click step with azide-tagged fluorophores or other reporter moieties. The PEG4 linker supports probe stability and helps limit non-specific interactions, making this reagent a practical choice for constructing modular imaging reagents used in research microscopy, assay development, and optical labeling workflows.

4. Diagnostic Reagent And Assay Platforms

endo-BCN-PEG4-NHS ester is well suited for preparing clickable components for diagnostic reagent development, including conjugates used in assay formats where modular assembly is advantageous. The NHS ester enables straightforward installation of BCN onto amine-functional assay reagents such as capture proteins, affinity binders, or scaffolded nanoparticles, while the BCN handle supports later SPAAC coupling to azide-bearing detection elements. This two-step conjugation strategy supports flexible reagent design, allowing teams to swap azide-functional reporters or secondary components while keeping the BCN-functionalized primary reagent consistent across assay batches.