Azido-PEG5-NHS ester | CAS 1433996-86-1

Azido-PEG5-NHS ester is a PEG-based heterobifunctional linker that combines an azide handle with an N-hydroxysuccinimide (NHS) ester for efficient coupling to primary amines. As a click chemistry reagent, it is commonly used as the azide partner for strain-promoted or copper-catalyzed azide–alkyne cycloaddition to enable modular assembly of labeled biomolecules, surfaces, and materials. The flexible PEG5 spacer improves solubility and reduces steric constraints, making this reagent widely relevant for bioconjugation workflows where controlled attachment and subsequent click-based functionalization are required.

1. Protein Amine Labeling

Azido-PEG5-NHS ester is used to introduce an azide functional group onto proteins, peptides, and antibody fragments by reacting the NHS ester with accessible primary amines such as lysine residues and N-termini. The resulting azide-bearing conjugates are then carried forward into downstream click chemistry steps to attach fluorophores, affinity tags, or imaging reagents while maintaining the original biomolecule’s recognition properties. In practice, this reagent is favored in research workflows that require a reliable, amine-reactive “handle installation” step followed by orthogonal labeling using azide–alkyne coupling chemistry.

2. Surface And Material Functionalization

Azido-PEG5-NHS ester is applied to functionalize biomaterial surfaces and polymeric substrates that present reactive amines, including amine-derivatized nanoparticles, membranes, and coatings. By installing azide groups through NHS ester chemistry, researchers can create stable, reactive interfaces that later undergo click conjugation with alkyne-bearing ligands or probes under conditions compatible with sensitive materials. The PEG5 spacer helps maintain accessibility of the azide moiety at the surface, supporting efficient subsequent coupling and improved uniformity in multistep material labeling strategies.

3. Multicolor Imaging Probe Building

Azido-PEG5-NHS ester supports modular construction of imaging probes by enabling sequential conjugation: first, azide installation onto a targeting scaffold or carrier, and then click-based attachment of imaging dyes or reporter groups bearing complementary alkyne functionality. This approach is widely used in fluorescence microscopy, flow cytometry labeling panels, and imaging reagent development where orthogonal reactivity and late-stage diversification are valuable. The PEG5 linker often improves reagent solubility and reduces nonspecific interactions, which can be particularly helpful when generating probe libraries that require consistent labeling chemistry across different targets.

4. Targeting Ligand And Probe Conjugates

Azido-PEG5-NHS ester is commonly used to prepare azide-functional targeting ligands and probe conjugates, including azide-modified peptides, enzyme substrates, and affinity binders that are subsequently decorated via click chemistry. The NHS ester enables straightforward coupling to amine-containing ligands, while the azide provides a convenient reactive handle for attaching complementary moieties such as cell-binding ligands, detection chemistries, or enrichment tags. This reagent is therefore well suited to workflows that require controlled, stepwise assembly of multifunctional research reagents with flexible downstream customization.