Azido-PEG5-t-butyl ester | CAS 1415800-41-7

Azido-PEG5-t-butyl ester is a PEG-based azide click handle designed for bioorthogonal conjugation workflows. As an azide-bearing reagent, it is commonly used in strain-promoted or copper-catalyzed azide–alkyne cycloaddition (click chemistry) to attach PEGylated motifs to biomolecules, surfaces, and imaging/diagnostic scaffolds. The t-butyl ester provides a protected carboxylate functionality that can be leveraged for controlled downstream functionalization while the PEG5 spacer supports solubility and reduced nonspecific interactions in complex chemical biology settings.

1. PEGylated Biomolecule Labeling

Azido-PEG5-t-butyl ester is widely used to introduce a flexible PEG5 spacer bearing an azide functionality onto proteins, peptides, and other biomolecular constructs prior to click conjugation. Researchers select this reagent when they want to improve aqueous handling, tune hydrodynamic properties, and create a robust attachment point for subsequent coupling to alkyne-functional partners such as fluorescent dyes, affinity tags, or cell-surface ligands. The protected ester format is particularly useful for workflows where a carboxylate handle is needed for later derivatization or for maintaining compatibility with multi-step labeling strategies.

2. Surface and Material Functionalization

Azido-PEG5-t-butyl ester supports the preparation of azide-functional coatings and materials used in chemical biology and biomaterials research. By incorporating the azide-PEG5 motif onto polymer films, hydrogel surfaces, or inorganic/organic hybrid materials, teams can create modular platforms for subsequent click attachment of probes, capture reagents, or antifouling layers. The PEG5 spacer is commonly valued for reducing nonspecific adsorption and for providing a hydrated interface that improves accessibility of the azide group during downstream conjugation to alkyne-bearing components.

3. Molecular Imaging Probe Conjugation

Azido-PEG5-t-butyl ester is frequently employed as a precursor for building imaging and detection probes that require controlled spacing between a targeting or reporter element and the conjugation junction. In molecular imaging reagent development, the PEG5 linker helps manage steric effects and improves solubility of probe conjugates, while the azide enables efficient click coupling to alkyne-functional fluorophores or imaging reporters. The reagent’s protected ester functionality can be advantageous when probe architectures require a carboxylate-containing intermediate for further scaffold assembly or for compatibility with standardized conjugation chemistries used across probe libraries.

4. Diagnostic Reagent and Assay Building

Azido-PEG5-t-butyl ester is used to generate azide-enabled building blocks for diagnostic reagent development and assay reagent platforms. In laboratory and industrial assay workflows, the reagent provides a convenient PEGylated click handle for attaching detection components such as fluorogenic reporters, affinity ligands, or signal-generating tags to assay surfaces and carriers. The PEG5 spacer supports consistent conjugate behavior in buffered assay conditions and can help mitigate aggregation or surface fouling, which is important for reproducible performance in high-throughput assay development pipelines.