Azido-PEG4-amine | CAS 951671-92-4

Azido-PEG4-amine is a PEG-based azide building block designed for copper-free and copper-mediated click chemistry workflows, enabling efficient conjugation of biomolecules, surfaces, and polymeric materials through azide functionalization. The short, flexible PEG spacer (PEG4) improves solubility and reduces steric constraints, while the terminal amine supports downstream coupling to activated carboxylic acids, NHS-esters, isothiocyanates, or other amine-reactive handles. As a common click-compatible linker, Azido-PEG4-amine is widely used in chemical biology and materials research to install azide groups for subsequent strain-promoted alkyne-azide cycloaddition (SPAAC) or to enable modular assembly of fluorescent probes, affinity reagents, and biofunctionalized surfaces.

1. Protein Labeling Workflows

Azido-PEG4-amine is routinely used to introduce an azide handle into protein labeling pipelines, including labeling strategies that rely on orthogonal conjugation steps after initial biomolecule preparation. The PEG spacer helps maintain reagent accessibility on protein surfaces, which is particularly useful when attaching bulky imaging tags or affinity ligands that require reliable presentation of the reactive group. Researchers commonly pair Azido-PEG4-amine with activated carboxylates or amide-coupling chemistries to generate azide-bearing protein conjugates that can be rapidly transformed into fluorescent or affinity-functional products via subsequent click reactions.

2. Fluorescent Probe Conjugation

Azido-PEG4-amine supports the construction of modular fluorescent probes by providing a convenient azide-functional linker for attaching dyes, quenchers, or reporting moieties through click-compatible chemistries. The PEG4 segment improves aqueous compatibility and can reduce nonspecific interactions that sometimes arise from more hydrophobic linkers, which benefits probe performance in labeling and imaging reagent development workflows. In practice, Azido-PEG4-amine is used as a linker intermediate to generate azide-tagged probe precursors that are then clicked to complementary alkyne-bearing fluorophores or imaging reagents.

3. Surface and Material Functionalization

Azido-PEG4-amine is well suited for biointerface engineering and materials functionalization where azide groups must be presented on surfaces for later click-based attachment of biomolecular coatings. The terminal amine enables coupling to a range of activated substrates, including carboxyl-functional surfaces and amine-reactive materials, allowing researchers to create azide-functional coatings that can be further addressed with alkyne-containing ligands. This approach is widely adopted in developing functionalized biosensor surfaces, cell-interaction materials, and polymer materials that require spatially controlled immobilization of clickable biomolecules.

4. Affinity Reagent and Linker Design

Azido-PEG4-amine is frequently used to design affinity reagents and modular linkers for assembling multi-component biochemical tools, where an azide handle is needed for later conjugation to targeting or capture elements. The amine functionality provides a practical outlet for installing the PEG-azide unit onto carriers such as beads, resins, or scaffold molecules, while the azide enables downstream click coupling to complementary partners. This makes Azido-PEG4-amine a common choice for generating intermediate linker constructs used in affinity pull-down workflows, diagnostic reagent development, and research-grade assay reagent assembly requiring robust modularity.