Azido-PEG2-acetic acid | CAS 882518-90-3

Azido-PEG2-acetic acid is a PEG-based azide building block designed for copper-free and copper-mediated click chemistry workflows, most commonly serving as the azide partner in strain-promoted or CuAAC conjugation strategies. Its short, flexible PEG spacer coupled to a terminal azide and carboxylic acid enables incorporation into biomolecule labeling, surface functionalization, and probe construction where improved solubility and reduced nonspecific interactions are valuable. The presence of a defined handle for downstream coupling makes this reagent widely used in chemical biology, materials chemistry, and molecular imaging reagent development.

1. Biomolecule Labeling Probes

Azido-PEG2-acetic acid is frequently used as an azide-functional handle for installing PEG spacers onto proteins, peptides, and nucleic-acid–associated reagents prior to conjugation with complementary alkyne partners. Researchers select this reagent when they need a compact, hydrophilic linker that can help maintain probe solubility and accessibility during labeling workflows, including affinity reagents and assay-compatible molecular tags. The terminal carboxylic acid also supports straightforward downstream coupling to activated esters or carbodiimide-mediated chemistries, enabling modular assembly of multi-component labeling reagents for cell-surface or extracellular targeting studies.

2. Surface and Hydrogel Functionalization

Azido-PEG2-acetic acid is commonly incorporated into material surfaces and soft biomaterials to introduce azide groups for subsequent click-based attachment of fluorescent reporters, affinity ligands, or bioactive coatings. Because the PEG spacer mitigates aggregation and promotes aqueous compatibility, it is well suited for functionalizing polymer films, nanoparticles, and hydrogel matrices where uniform presentation of reactive sites is important. The carboxylic acid functionality supports tethering strategies to pre-functionalized surfaces, allowing azide density tuning for reproducible conjugation of imaging dyes, capture molecules, or analytical tags.

3. Molecular Imaging Reagent Assembly

Azido-PEG2-acetic acid is used as a building block to prepare imaging probes and diagnostic reagent components that require rapid, selective conjugation to alkyne-bearing dyes, reporters, or targeting scaffolds. The azide handle enables orthogonal coupling in complex labeling mixtures, while the short PEG spacer helps maintain dispersion of hydrophobic reporter moieties and supports consistent probe behavior in aqueous assay buffers. This reagent is particularly relevant for constructing modular imaging constructs where the azide-bearing linker is introduced early, then clicked to the desired reporter component under standardized conjugation conditions.

4. Diagnostic and Assay Reagent Conjugates

Azido-PEG2-acetic acid is widely used to generate azide-functional conjugates for research diagnostics and analytical assay development, including enzyme-linked or binding-based reagent systems that rely on click-compatible labeling steps. The carboxylic acid provides a convenient point for attaching the azide-bearing linker to carriers such as polymers, beads, or activated biomolecule scaffolds, while the PEG spacer improves handling and reduces nonspecific adsorption during assay preparation. Teams developing multiplexed assay panels often favor this reagent because it offers a simple, standardized azide unit that can be exchanged across different probe formats while keeping conjugation chemistry consistent.