N-(Azido-PEG2)-N-Boc-PEG4-NHS ester | CAS 2093153-95-6

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester is a heterobifunctional, PEG-based click chemistry reagent that combines an NHS ester for efficient amide coupling to primary amines with a terminal azide handle for strain-promoted or copper-catalyzed azide–alkyne cycloaddition workflows. The extended PEG spacers and protected amine functionality are designed to improve aqueous compatibility and provide controlled reactivity during bioconjugation and subsequent labeling steps. This reagent is commonly used in chemical biology and biomaterials research to install azide-functional linkers onto proteins, peptides, and polymeric surfaces, enabling modular downstream attachment of dyes, affinity tags, and imaging/assay components via click chemistry.

1. Protein And Peptide Labeling

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester is widely used to functionalize proteins and peptides by coupling the NHS ester to lysine side chains or N-terminal amines, generating azide-bearing conjugates for later click-based modification. Researchers value the PEG4 spacer for reducing steric constraints and improving conjugate solubility, which is particularly helpful when preparing labeled reagents for biochemical assays, receptor-binding studies, or workflow-compatible imaging probes. The azide functionality installed on the biomolecule provides a stable, orthogonal handle that can be carried through purification steps and then selectively reacted with complementary alkyne partners to introduce fluorophores, affinity moieties, or other modular tags.

2. Surface Functionalization For Materials

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester supports azide installation on material surfaces and biomaterial coatings through amine-reactive coupling, making it a practical choice for preparing clickable interfaces on polymer films, hydrogel matrices, and functionalized nanoparticles. By introducing azide groups with a PEG spacer, the reagent helps maintain accessibility of the reactive handle at the surface, which improves compatibility with downstream click conjugation to attach ligands, imaging agents, or crosslinking components. This approach is commonly used in materials chemistry and molecular imaging tool development, where azide-functional surfaces serve as modular platforms for assembling multilayer constructs or immobilizing capture molecules in a controlled manner.

3. Targeting Ligand Conjugates

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester is frequently employed to generate azide-functional targeting ligands by coupling to amine-containing targeting scaffolds such as peptides, antibody fragments, or enzyme-binding domains used in research reagent construction. The resulting azide conjugates can then be reacted with alkyne-bearing reporters or scaffolds to build multivalent constructs, enabling flexible design of labeling strategies for microscopy, flow-based assays, and affinity workflows. The PEG spacing helps preserve the binding-relevant conformation of the ligand while providing a reactive azide site for orthogonal attachment, which is advantageous when assembling complex probe architectures from modular components.

4. Molecular Imaging Probe Assembly

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester is used as an azide-installing reagent in the preparation of molecular imaging and detection tool candidates, where an NHS-activated PEG linker is first attached to an amine-bearing targeting or carrier component and then clicked to an alkyne-functional imaging reporter. This two-step, handle-based strategy supports late-stage assembly of probes, allowing researchers to swap reporter groups while keeping the targeting or scaffold component constant. The PEG-rich linker architecture improves aqueous handling and can reduce nonspecific interactions during probe formulation, which is beneficial for producing consistent imaging reagents for instrument-based readouts and comparative analytical studies.

5. Diagnostic Reagent And Assay Development

N-(Azido-PEG2)-N-Boc-PEG4-NHS ester is commonly integrated into assay reagent development pipelines to create azide-functional conjugates used as clickable building blocks for diagnostic-style assay formats and research detection reagents. Amine coupling via the NHS ester enables incorporation of the azide handle onto assay-relevant proteins, affinity reagents, or carrier molecules, after which alkyne-functional components such as fluorophores, quencher partners, or signal-amplifying tags can be attached through click chemistry. The reagent’s PEG spacers support stable conjugate behavior in aqueous assay conditions and help maintain accessibility of the azide for efficient downstream labeling, supporting reproducible reagent construction for high-throughput and multiplexing workflows.