Azido-PEG9-acid | CAS 1670249-37-2

Azido-PEG9-acid is a PEG-based azide-functional building block designed for copper-free and copper-mediated click chemistry workflows, enabling robust conjugation of azide handles onto biomolecules, surfaces, and polymeric materials. The reagent features a terminal carboxylic acid for convenient coupling into downstream constructs while maintaining the azide group as a versatile click partner for strain-promoted or alkyne-based ligation strategies. Its PEG spacer supports improved solubility and spacing in bioconjugation and molecular imaging reagent development, where controlled attachment and reduced steric interference are often critical.

1. Bioconjugation Linker Chemistry

Azido-PEG9-acid is widely used as a practical PEG-azide linker to introduce an azide functional handle onto proteins, peptides, and other targeting ligands that already contain reactive groups for carboxyl-mediated coupling. In research workflows, the carboxylic acid enables incorporation into activated ester or amide-forming strategies, while the azide moiety is preserved for subsequent click attachment to complementary partners such as strained cyclooctynes or terminal alkynes. This makes the reagent valuable for assembling modular conjugates used in chemical biology, including affinity reagents, multivalent binders, and probe libraries where orthogonal labeling and consistent linker length improve reproducibility.

2. Surface Functionalization And Coatings

Azido-PEG9-acid supports click-compatible surface engineering by providing a stable azide-bearing linker that can be anchored through its carboxylic acid functionality to material platforms with appropriate coupling chemistries. Researchers use this reagent to create azide-functional coatings and interfaces that can later be decorated with fluorescent tags, affinity motifs, or other clickable components under mild conditions. The PEG spacer helps maintain accessibility of the azide group at the surface, which is particularly useful for constructing biointerface materials, assay surfaces, and patterned substrates where spatial control over subsequent labeling is required.

3. Molecular Imaging Probe Assembly

Azido-PEG9-acid is commonly incorporated into molecular imaging probe development pipelines as a linker that enables modular attachment of imaging reporters to biomolecular scaffolds. The azide handle allows efficient downstream conjugation to alkyne-bearing reporters or cyclooctyne-based imaging moieties, facilitating rapid exchange of targeting components and signal units during probe optimization. The PEG9 chain contributes to improved solubility and reduced nonspecific interactions in many labeling contexts, making the reagent a frequent choice for assembling chemically defined imaging reagents and tool compounds used in imaging reagent screening and characterization.

4. Diagnostic Reagent And Assay Labeling

Azido-PEG9-acid is used to generate click-ready labeling intermediates for diagnostic reagent development and assay construction, where consistent conjugation chemistry is essential for reproducible signal generation. By installing an azide group via the carboxylic acid functionality, the reagent enables later coupling to assay-compatible detection handles, such as alkyne-functional fluorophores, affinity tags, or reporter constructs used in multiplexed formats. The PEG spacer supports effective presentation of the clickable group, which can improve labeling efficiency in complex assay matrices and helps maintain performance across different reagent batches and assay workflows.