Azido-PEG2-amine | CAS 166388-57-4

Azido-PEG2-amine is a polyethylene glycol (PEG)-spaced primary amine bearing a terminal azide, designed for copper-free or copper-mediated azide–alkyne click chemistry workflows. As a small, water-compatible bifunctional linker, it combines the orthogonal reactivity of an azide handle with an amine for downstream coupling to activated carboxylates, NHS-esters, or other electrophiles. This reagent is commonly used to introduce a short, hydrophilic PEG spacer that improves solubility and reduces nonspecific interactions in probe, surface, and biomolecule conjugation pipelines.

1. PEGylated Bioconjugation Linker

Azido-PEG2-amine is frequently used as a modular PEGylation handle to build conjugates for chemical biology and biomaterials research, where a defined azide functionality is required for subsequent click attachment. The short PEG spacer supports improved aqueous handling and can help moderate steric effects when attaching dyes, affinity tags, or imaging moieties to proteins, peptides, and nucleic-acid-binding reagents. The terminal amine also enables direct incorporation into larger constructs through standard amide-forming chemistries, allowing researchers to position the azide for later, orthogonal labeling steps.

2. Fluorophore and Probe Labeling

Azido-PEG2-amine serves as a practical intermediate for preparing azide-bearing fluorescent probes and detection reagents that are compatible with click-based modular assembly. Researchers use it to append a small PEG spacer between a reactive biomolecule scaffold and a clickable handle, supporting consistent probe behavior in labeling assays and imaging workflows. The azide group enables efficient attachment of alkyne-functional reporters, while the amine functionality supports coupling to probe carriers such as activated dyes, haptens, or scaffold molecules used in analytical chemistry and molecular imaging development.

3. Surface and Material Functionalization

Azido-PEG2-amine is widely applied in the functionalization of polymeric and biomaterial surfaces where azide presentation is needed for subsequent click immobilization. The PEG spacer helps improve wetting and reduces surface aggregation compared with shorter linkers, which is valuable when anchoring ligands onto hydrogels, coatings, nanoparticles, or microfabricated substrates. The amine can be used to couple the reagent to carboxyl-activated surfaces or other electrophilic materials, generating stable azide-bearing interfaces for later attachment of alkyne-tagged biomolecules, affinity ligands, or reporter groups.

4. Targeting Ligand Conjugates

Azido-PEG2-amine is useful for constructing targeting-ligand conjugates and affinity reagents that rely on click chemistry for late-stage assembly. By incorporating an azide-bearing PEG spacer, teams can connect targeting moieties to secondary components such as multivalent binders, imaging reporters, or enrichment handles with controlled linker length and improved solubility. The amine provides a convenient handle for coupling the reagent to ligand scaffolds or carrier backbones, while the azide is reserved for orthogonal attachment during the final conjugation step, supporting streamlined reagent development workflows.