N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) | CAS 2353409-58-0

N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) is a PEG-based azide functionalization reagent designed for copper-free and copper-mediated azide–alkyne click chemistry workflows. The structure combines a terminal azide handle for bioorthogonal conjugation with multiple PEG segments that provide aqueous solubility and spacing control, while t-butyl ester groups enable ester-reactive or deprotection-responsive behavior in downstream material and bioconjugation formats. This reagent is commonly used as a versatile linker/building block in research-grade probe labeling, surface modification, and polymer or biomolecule functionalization where controlled hydrophilicity and click-ready coupling are required.

1. Biomolecule Conjugation

N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) is frequently used to introduce a click-reactive azide handle onto biomolecule conjugates and biomolecular surfaces while maintaining strong aqueous compatibility through its PEG architecture. Researchers apply this reagent to prepare azide-functional intermediates for subsequent coupling to alkyne-bearing partners, including labeled ligands, affinity reagents, and imaging tags, enabling modular assembly of complex conjugates. The PEG spacing helps reduce steric congestion during labeling and supports consistent presentation of the reactive handle for downstream click coupling steps.

2. Molecular Imaging Probes

N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) supports the construction of imaging and detection probes by providing an azide functional group for reliable attachment to alkyne-containing reporters. Probe developers use the PEG-rich scaffold to improve solubility and to tune the hydrodynamic environment of the final conjugate, which is particularly valuable when integrating fluorophores, enrichment handles, or other bulky reporter moieties. The t-butyl ester functionality is often leveraged during probe assembly to enable controlled intermediate processing and to facilitate incorporation into probe formats that require ester-responsive handling prior to final conjugate generation.

3. Surface And Material Functionalization

N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) is used in biomaterials and materials research to functionalize surfaces and polymeric substrates with click-ready azide groups. Material scientists incorporate this reagent to create hydrophilic, PEG-mediated interphases that improve wetting and reduce nonspecific interactions, while still presenting an azide handle for subsequent attachment of alkyne-functional coatings, capture ligands, or crosslinking components. This approach is commonly adopted in the development of functional coatings, hydrogel modification strategies, and surface-tethered reagent platforms where controlled attachment chemistry is essential.

4. Polymer and Hydrogel Crosslinking

N-(Azido-PEG3)-N-bis(PEG4-t-butyl ester) is well suited for building polymer and hydrogel architectures that require click-compatible functional handles for network formation or post-assembly modification. In polymer chemistry and chemical biology workflows, the reagent is incorporated to introduce azide functionality that can be coupled to alkyne-bearing crosslinkers, degradable motifs, or affinity elements, allowing stepwise construction of complex materials. PEG spacing and water compatibility are particularly valuable for forming reproducible conjugation environments in soft materials, where uniform functional group distribution strongly influences downstream labeling and material performance.