Azido-PEG2-propionic acid | CAS 1312309-63-9

Azido-PEG2-propionic acid is a PEG-based azide building block designed for copper-free click chemistry workflows and downstream bioconjugation strategies. As an azide-functionalized, water-compatible linker, it provides a flexible handle for strain-promoted azide–alkyne cycloaddition (SPAAC) labeling and for modular assembly of PEGylated probes, surfaces, and biomaterials. Its short PEG spacer and carboxylic acid functionality make it particularly useful when a reactive azide tag must be introduced alongside a convenient site for coupling, immobilization, or further derivatization in research-grade reagent development.

1. SPAAC Probe Labeling

Azido-PEG2-propionic acid is commonly used to install an azide-bearing PEG spacer onto small-molecule probes, fluorophores, and imaging reagents that are later coupled via SPAAC to complementary cyclooctyne/DBCO partners. The PEG2 segment helps maintain solubility and reduces nonspecific interactions during labeling and purification, which is valuable for creating consistent probe conjugates for biochemical assays and molecular imaging tool development. The terminal carboxylic acid also supports additional coupling steps when probe formats require attachment to carrier scaffolds, affinity handles, or polymeric components.

2. Biomolecule Conjugation Linker

Azido-PEG2-propionic acid serves as a practical azide-containing linker for constructing azide-functional biomolecule conjugates used in chemical biology and biomaterials research. Researchers incorporate it into labeling schemes where a carboxylate-bearing PEG spacer is needed to connect to proteins, peptides, or other biomolecular scaffolds through standard carbodiimide-mediated coupling or through activated carboxyl derivatives. The resulting azide-functional conjugates can then be reacted with cyclooctyne/DBCO-functional reagents to generate modular constructs for tracking, affinity studies, and multicomponent probe assembly without relying on azide reduction or harsh post-modification conditions.

3. Surface Immobilization Chemistry

Azido-PEG2-propionic acid is frequently selected for preparing azide-functional surfaces and coatings that enable subsequent SPAAC patterning with cyclooctyne-functional molecules. The combination of an azide group and a carboxylic acid allows straightforward immobilization strategies on activated substrates, including polymer films, resin-bound materials, and other carboxyl-reactive platforms, producing stable, spacing-controlled functional layers. Such azide-functional interfaces are widely used to build spatially addressable reagent surfaces for assay development, binding studies, and materials-based chemical biology workflows where controlled presentation of reactive handles is critical.

4. PEGylated Material Functionalization

Azido-PEG2-propionic acid is used to introduce azide functionality into PEGylated materials and soft matter systems where flexible spacing improves compatibility and reduces aggregation. Material scientists and biomaterials teams incorporate this reagent into polymer modification workflows to create azide-bearing networks that can be crosslinked or decorated through SPAAC with cyclooctyne-modified components. The short PEG spacer supports aqueous processing and helps tune local mobility of functional groups, making it suitable for generating reproducible functional materials used in probe immobilization, multivalent reagent display, and modular assembly of composite material platforms for laboratory research applications.