Azido-PEG3-Sulfone-PEG4-acid | CAS 2055024-42-3

Azido-PEG3-Sulfone-PEG4-acid is a PEG-based azide-containing click chemistry reagent designed for bioorthogonal conjugation workflows. Its structure combines an azide handle for strain-promoted or copper-catalyzed azide–alkyne cycloaddition compatibility with a sulfone-linked PEG spacer and a terminal carboxylic acid for downstream coupling to activated esters, carbodiimide chemistry, or surface immobilization. This reagent is commonly used in molecular imaging probe construction, polymer and biomaterial functionalization, and multicomponent labeling strategies where controlled hydrophilicity and spacer length are important for maintaining solubility and accessibility of reactive groups.

1. Bioorthogonal Probe Labeling

Azido-PEG3-Sulfone-PEG4-acid is widely used to introduce an azide-bearing PEG spacer into molecular imaging and labeling probes, enabling modular assembly with complementary alkyne-functional partners. The PEG-rich architecture helps reduce nonspecific interactions and improves aqueous compatibility, which is particularly valuable when preparing fluorescent, affinity, or luminescent reporter conjugates for assay development and analytical studies. The terminal carboxylic acid further supports straightforward incorporation into probe scaffolds that require a defined handle for subsequent activation or coupling to carrier molecules such as peptides, proteins, or polymer backbones.

2. Surface And Material Functionalization

Azido-PEG3-Sulfone-PEG4-acid is suitable for functionalizing surfaces and bulk materials where a stable, hydrophilic spacer is needed to present reactive azide groups at a controlled distance from the material interface. Researchers use it to prepare azide-terminated coatings, linker layers, and scaffold materials that can be clicked with alkyne-bearing biomolecules, dyes, or capture ligands during materials development. The sulfone-PEG segment supports robust linker behavior in aqueous processing steps, while the acid group enables coupling to surface chemistries that rely on carboxylate activation or layer-by-layer attachment strategies.

3. Protein And Peptide Conjugation Handles

Azido-PEG3-Sulfone-PEG4-acid is commonly incorporated as a linker precursor in protein and peptide conjugation workflows that require an azide functionality for orthogonal attachment to alkyne-modified reagents. The PEG spacing can help maintain conjugate solubility and reduce steric hindrance, supporting more consistent labeling of biomolecular targets in research-grade reagent preparation. The carboxylic acid enables efficient derivatization into activated intermediates that can be used to attach the azide-bearing linker to amine-containing biomolecules or other carboxyl-reactive platforms prior to click coupling.

4. Multicomponent Polymer And Nanoconjugates

Azido-PEG3-Sulfone-PEG4-acid is used in the construction of multicomponent polymer conjugates and nanoconjugate building blocks where sequential functionalization is required. The azide group allows post-synthetic modular assembly with alkyne-functional imaging agents, affinity tags, or crosslinking components, while the PEG spacer provides a tunable, water-friendly environment that can improve colloidal stability and accessibility of appended groups. The terminal acid supports integration into polymer architectures through standard coupling chemistry, enabling reproducible preparation of clickable macromolecular platforms for research tool development and analytical reagent manufacturing.