Azido-PEG4-t-butyl ester | CAS 581066-04-8

Azido-PEG4-t-butyl ester is a PEG-based azide click chemistry reagent designed for bioorthogonal conjugation workflows, typically used in strain-promoted or copper-catalyzed azide–alkyne cycloaddition (CuAAC) formats. The reagent combines an azide functional handle with a short polyethylene glycol spacer and a t-butyl ester motif that supports controlled reactivity and convenient incorporation into linker architectures. Its PEG character is commonly leveraged to improve solubility and reduce nonspecific interactions when building labeled probes, conjugated biomolecules, and functionalized surfaces for chemical biology and materials research.

1. Probe And Label Conjugation

Azido-PEG4-t-butyl ester is widely used as a modular azide building block for generating fluorescent, affinity, or enrichment probes via click conjugation to complementary alkyne partners. Researchers incorporate this reagent into labeling schemes for proteins, peptides, and small-molecule scaffolds where a PEG spacer helps maintain probe accessibility and improves aqueous handling. The t-butyl ester functionality is particularly useful during intermediate assembly steps, enabling practical preparation of conjugation-ready constructs before installing the final clickable handle into the desired targeting or reporting format.

2. Surface Functionalization For Materials

Azido-PEG4-t-butyl ester supports the creation of azide-functional coatings and material surfaces that can be further patterned or functionalized by click chemistry. Biomaterials and materials science groups use azide-bearing PEG linkers to tune surface wettability, spacing, and steric presentation of reactive groups, which is important when immobilizing biomolecules, affinity ligands, or imaging reagents onto polymers, hydrogels, or solid supports. The reagent’s PEG spacer is commonly selected to reduce crowding at the interface and to promote efficient downstream coupling to alkyne-functional reagents.

3. Bioconjugation Linker Synthesis

Azido-PEG4-t-butyl ester is frequently employed in bioconjugation chemistry as a linker precursor for constructing defined conjugates with controlled spacing between biomolecular components and the click handle. Chemical biology laboratories use it to prepare intermediate conjugates that later undergo click coupling to install tags such as dyes, affinity groups, or molecular imaging moieties. The short PEG4 segment helps balance flexibility and distance control, which is valuable when designing conjugation strategies that require the clickable azide to remain accessible after attachment to a larger macromolecular framework.

4. Molecular Imaging Reagent Building

Azido-PEG4-t-butyl ester is used to assemble imaging and detection reagents that rely on azide–alkyne click coupling for rapid, modular synthesis. Imaging reagent developers often choose PEG-based azide linkers to manage solubility and to help maintain the spatial presentation of the imaging label relative to the targeting scaffold. By providing a convenient azide handle with a tunable PEG spacer, Azido-PEG4-t-butyl ester fits workflows where researchers generate a library of alkyne-bearing imaging constructs and then couple them to azide-containing intermediates to streamline probe development.