Azido-PEG9-t-butyl ester | CAS 1818294-43-7

Azido-PEG9-t-butyl ester is a PEG-based azide building block designed for copper-free or copper-mediated click chemistry workflows, enabling efficient conjugation to complementary alkyne partners in chemical biology and materials research. The reagent couples a terminal azide handle with a PEG9 spacer and a t-butyl ester functionality, which supports downstream derivatization strategies where hydrophilicity, spacing, and reactive group presentation are critical. Because the azide moiety is widely used as a modular labeling handle, Azido-PEG9-t-butyl ester is commonly selected for preparing functional probes, surface-reactive linkers, and PEGylated intermediates for controlled bioconjugation and imaging reagent development.

1. PEGylated Bioconjugation Linkers

Azido-PEG9-t-butyl ester is frequently used to introduce a PEG spacer between a targeting or recognition element and an azide-bearing conjugation site, improving solubility and reducing nonspecific interactions in labeling workflows. Researchers incorporate this reagent into bioconjugation strategies where an azide-functional handle must be presented at a defined distance from a biomolecule, such as in probe libraries and reagent panels for affinity-based assays. The t-butyl ester group also supports preparation of PEGylated intermediates that can be further transformed into carboxylate-containing linkers for attachment to amines or other nucleophiles, enabling flexible assembly of multicomponent conjugates.

2. Surface and Material Functionalization

Azido-PEG9-t-butyl ester is well suited for functionalizing polymeric and biomaterial surfaces with click-reactive azide groups, supporting the fabrication of patterned or uniformly modified materials. In materials science workflows, the PEG spacer helps manage surface hydration and accessibility of the reactive handle, which is important when immobilizing capture ligands, incorporating bioactive coatings, or building multilayer constructs using orthogonal chemistries. The reagent’s azide functionality enables post-modification with alkyne-bearing moieties, allowing researchers to tune surface chemistry without requiring direct modification of the base material during initial fabrication.

3. Molecular Imaging Probe Preparation

Azido-PEG9-t-butyl ester is commonly employed as a labeling intermediate for constructing imaging probes and molecular reporters that require a stable azide handle for modular attachment to reporter scaffolds. Probe developers use the PEG9 spacer to optimize probe behavior in labeling and purification steps, particularly when attaching bulky fluorophores, affinity tags, or other diagnostic-relevant components via click coupling to alkyne-functional partners. The t-butyl ester provides a convenient functional handle for generating downstream linker forms that can be integrated into probe architectures where controlled connectivity and aqueous compatibility are important for consistent reagent handling.

4. Diagnostic Reagent and Assay Platforms

Azido-PEG9-t-butyl ester is used to build azide-functional components for assay reagent platforms, including conjugate standards, labeling reagents, and immobilization-ready linkers. In diagnostic reagent development workflows, the PEG spacer supports improved dispersion and reduced aggregation tendencies during reagent preparation, which can be advantageous for reproducible conjugate performance in complex assay buffers. Developers often rely on the modular azide-to-alkyne click step to assemble multivalent constructs, such as polymeric labeling systems or bead-based reagent formats, where the azide handle must be introduced early and coupled later to maintain flexibility across assay formats.