Azido-PEG4-(CH2)3-methyl ester | CAS 1835759-71-1

Azido-PEG4-(CH2)3-methyl ester is a PEG-based azide building block designed for bioorthogonal click chemistry, most commonly used as an azide partner in strain-promoted or copper-catalyzed azide–alkyne cycloaddition workflows. The reagent combines a flexible PEG4 spacer with a terminal azide handle and a methyl ester functional group, enabling downstream coupling to carboxylate-bearing targets and versatile surface or biomolecule labeling strategies. Its amphiphilic, water-compatible architecture is frequently leveraged in chemical biology, materials functionalization, and probe development where controlled linker length and orthogonal reactivity are important.

1. Biomolecule Conjugation Linker

Azido-PEG4-(CH2)3-methyl ester is used as a click-reactive linker for introducing an azide handle onto proteins, peptides, and other macromolecular platforms prior to subsequent conjugation via azide–alkyne cycloaddition. The PEG4 spacer helps maintain accessibility of the reactive group and reduces steric congestion, which is valuable when labeling densely functionalized biomolecules or preparing multi-component conjugates for imaging and assay development. The methyl ester functionality provides a practical intermediate for generating carboxylate-containing derivatives that can be incorporated into labeling schemes for research-grade bioconjugates.

2. Surface And Material Functionalization

Azido-PEG4-(CH2)3-methyl ester is well suited for functionalizing polymeric and biomaterials surfaces that require azide incorporation followed by click attachment of dyes, affinity ligands, or reporter moieties. The PEG spacer supports more uniform presentation of the azide group at interfaces, which can improve consistency in downstream attachment density when preparing patterned surfaces, coatings, or hydrogel modifications. In materials science workflows, the methyl ester handle also supports intermediate derivatization steps that help integrate the linker into material chemistries before final click coupling.

3. Molecular Imaging Probe Assembly

Azido-PEG4-(CH2)3-methyl ester is commonly incorporated into molecular imaging probe construction pipelines where azide-bearing intermediates are needed to attach fluorophores, quencher units, or other imaging reporters through click chemistry. The PEG4-(CH2)3 linker architecture supports solubility and flexible spacing between the imaging label and the targeting scaffold, which is often important for maintaining probe behavior in complex labeling environments. Researchers use this reagent to standardize probe synthesis by providing a reliable azide handle that can be modularly coupled to alkyne-functional reporters.

4. Diagnostic Reagent And Assay Development

Azido-PEG4-(CH2)3-methyl ester is used to prepare azide-functional reagents for assay development, including labeling components that later undergo click conjugation to generate detection-ready conjugates. The reagent’s linker design supports controlled spacing between functional groups, which is useful when assembling multivalent constructs such as labeled binding reagents or reporter-tagged assay components. By enabling modular azide introduction, it helps streamline workflows for producing consistent reagent batches used in research diagnostics and analytical assay optimization.