Azido-PEG1-acid | CAS 1393330-34-1

Azido-PEG1-acid is a short-chain, azide-functionalized polyethylene glycol (PEG) carboxylic acid designed for click chemistry workflows, most commonly as an azide partner in copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC). Its compact PEG spacer and terminal carboxyl group support solubility and subsequent coupling strategies, making it a practical building block for preparing azide-containing linkers, conjugation handles, and imaging or materials platforms. Because the azide moiety is orthogonal to many biomolecular functional groups, Azido-PEG1-acid is widely used to introduce a defined click handle into complex research samples and downstream conjugates.

1. Protein And Peptide Labeling

Azido-PEG1-acid is used as a convenient azide handle for installing clickable functionality onto proteins and peptides through carboxyl-activated coupling workflows, enabling subsequent attachment to alkyne-bearing probes, tags, or affinity reagents via CuAAC. The short PEG spacer helps maintain water compatibility and reduces nonspecific aggregation during labeling, which is particularly valuable when preparing multicomponent conjugates for biochemical assays, proteomics sample preparation, and surface-tethered biomolecule studies. Researchers commonly rely on Azido-PEG1-acid to generate azide-functionalized bioconjugates that can be modularly diversified with fluorescent reporters, affinity ligands, or enrichment tags while keeping the click step clean and selective.

2. Targeting Ligand Conjugation

Azido-PEG1-acid supports the construction of clickable targeting ligands by providing a stable azide-bearing linker that can be incorporated into small molecules, peptides, or ligand scaffolds containing a carboxyl-reactive site. After the azide-functional intermediate is prepared, CuAAC with alkyne-functional partners enables rapid assembly of multivalent constructs such as ligand–reporter hybrids or ligand–material conjugates, where the PEG carboxyl functionality assists in maintaining solubility and controlling the effective spacing between components. This application is common in chemical biology and molecular imaging reagent development, where modular conjugation strategies are used to rapidly generate libraries of labeled or surface-anchored targeting constructs.

3. Surface And Hydrogel Functionalization

Azido-PEG1-acid is widely applied in biomaterials workflows to introduce azide groups onto surfaces, polymer films, and hydrogel matrices, enabling post-fabrication click attachment of alkyne-functional biomolecules or imaging reagents. The PEG carboxylic acid motif is compatible with common immobilization approaches that tether the azide to material backbones, after which CuAAC provides a robust route to decorate materials with fluorescent probes, enzyme substrates, or cell-interaction components. In these settings, Azido-PEG1-acid helps create stable, defined reactive sites that support reproducible functionalization densities and straightforward downstream conjugation without requiring extensive chemical modification of sensitive biomolecules.

4. Molecular Imaging Probe Building

Azido-PEG1-acid is used as an azide building block for assembling molecular imaging and detection probes that require modular attachment to fluorophores, quencher units, or other alkyne-bearing reporter components. By incorporating the azide handle into a probe precursor or linker, teams can generate probe variants by selecting different alkyne partners and performing CuAAC under standardized conditions, improving workflow efficiency in probe development. The short PEG spacer and carboxyl functionality of Azido-PEG1-acid are especially helpful for balancing solubility and linker flexibility in probe constructs intended for in vitro imaging and analytical readouts, where consistent conjugation chemistry is critical for producing interpretable reagent batches.