Azido-PEG3-methyl ester | CAS 2086689-07-6

Azido-PEG3-methyl ester is a PEG-based azide building block designed for copper-free and copper-mediated click chemistry workflows, enabling efficient conjugation to complementary alkynes or strained cyclooctynes. The reagent combines a terminal azide handle with a short, flexible PEG3 spacer and a methyl ester functional group that can be carried into downstream labeling, immobilization, or linker elaboration. Its compact PEG architecture and orthogonal functional group set make it widely used in bioconjugation and molecular imaging reagent development where controlled spacing and reliable azide reactivity are required.

1. Biomolecule Conjugation

Azido-PEG3-methyl ester is commonly used to introduce an azide functionality onto proteins, peptides, and nucleic-acid derived materials prior to click-based attachment of dyes, affinity tags, or reporter groups. The PEG3 spacer helps reduce steric congestion around the reactive azide, which is particularly valuable when labeling densely functionalized biomolecules or when preserving binding or recognition properties of the target scaffold for assay development. Researchers also leverage the methyl ester as a convenient handle for subsequent chemical transformation or for tuning the overall linker chemistry during probe construction.

2. Surface Immobilization Chemistry

Azido-PEG3-methyl ester is frequently incorporated into workflows that require azide-bearing linkers for attaching biomolecules to solid supports such as polymer surfaces, hydrogel matrices, or microarray formats. The reagent’s PEG3 segment provides a hydrophilic, flexible tether that can improve accessibility of the conjugated ligands after immobilization, while the azide enables post-assembly coupling to alkyne-functional surfaces or patterned substrates. This approach is widely adopted in materials science and chemical biology labs building reusable capture platforms, affinity surfaces, and spatially resolved labeling tools.

3. Fluorophore and Probe Labeling

Azido-PEG3-methyl ester is used as a labeling intermediate for generating azide-functional probes that can be clicked to fluorescent dyes, quencher pairs, or luminescent reporters bearing complementary alkyne groups. The short PEG spacer supports consistent probe behavior by moderating local hydrophobic interactions and providing a defined distance between the reporter and the biomolecular or polymer scaffold. In molecular imaging and diagnostic reagent development, this reagent is often selected to create modular probe architectures where the azide handle is introduced early and the final reporter attachment is performed late in the workflow.

4. Linker Building for Diagnostics

Azido-PEG3-methyl ester supports diagnostic reagent development by serving as a modular linker precursor that can be converted into azide-bearing conjugates for assay components such as affinity reagents, signal transducers, or capture chemistries. The combination of an azide click handle and a methyl ester functionality enables flexible downstream linker chemistry, allowing teams to tailor solubility, conjugation density, and attachment strategies to the specific assay format. Many research groups use this reagent to standardize linker introduction across multiple probe variants, streamlining the generation of reagent libraries for platform optimization.