N-(Azido-PEG4)-N-bis(PEG4-NHS ester) | CAS 2353409-90-0

N-(Azido-PEG4)-N-bis(PEG4-NHS ester) is a multifunctional PEG-based click chemistry reagent that combines an azide handle for copper-free or copper-catalyzed azide–alkyne cycloaddition with two NHS ester groups for reactive coupling to primary amines. The reagent’s branched PEG architecture supports aqueous solubility and spatially controlled bioconjugation, making it well-suited for building modular conjugates where a single biomolecule or material is simultaneously functionalized for downstream click attachment. In research workflows, it is commonly used to introduce an azide “landing pad” while preserving NHS reactivity for efficient amine labeling of proteins, peptides, and PEGylated surfaces.

1. Protein Azide Labeling

N-(Azido-PEG4)-N-bis(PEG4-NHS ester) is frequently used to generate azide-functional protein conjugates for subsequent bioconjugation by click chemistry. The two NHS ester groups enable rapid coupling to lysine residues or N-terminal amines, while the azide moiety provides a convenient handle for attaching the labeled protein to alkynyl probes, affinity tags, or polymeric carriers. This design is especially valuable when a single conjugation step must both preserve biomolecular aqueous compatibility and create a defined attachment point for orthogonal downstream assembly.

2. Antibody and Peptide Conjugates

N-(Azido-PEG4)-N-bis(PEG4-NHS ester) supports workflows that require site-agnostic yet efficient functionalization of antibodies and peptides with an azide group for modular imaging reagent construction. By targeting accessible primary amines through NHS ester chemistry, researchers can install the azide handle without needing prefunctionalized building blocks, then use click coupling to connect the biomolecule to fluorescent dyes, imaging scaffolds, or other molecular ligands bearing terminal alkynes. The PEG spacer helps maintain conjugate solubility and reduces steric constraints that can otherwise limit labeling density and probe accessibility.

3. Surface and Material Functionalization

N-(Azido-PEG4)-N-bis(PEG4-NHS ester) is used to functionalize amine-containing surfaces and biomaterial platforms with azide groups for subsequent attachment of alkynyl components. NHS ester reactivity enables coupling to amine groups on coatings, hydrogels, polymer films, or pre-activated biomaterial layers, while the azide functionality allows later click immobilization of targeting ligands, reporter molecules, or crosslinking elements. This approach is commonly adopted in materials chemistry and chemical biology to create stable, modular interfaces for probe arrays and surface-based assays.

4. PEG Linker Assembly for Probes

N-(Azido-PEG4)-N-bis(PEG4-NHS ester) is well suited for constructing PEG-based linkers and intermediate conjugates that carry both amine-reactive and click-reactive functionality. The dual NHS ester groups allow incorporation into amine-bearing scaffolds or to pre-label a carrier molecule, and the azide handle then enables controlled attachment to alkynyl imaging reporters, enrichment tags, or analytical reagents. Such intermediates are widely used in molecular imaging and diagnostic reagent development pipelines where modular swapping of the final reporter component is needed without redoing the initial amine-coupling step.