Bromo-PEG4-azide | CAS 1951439-37-4

Bromo-PEG4-azide is a PEG-based bifunctional click chemistry reagent that combines a terminal azide for copper-free or copper-catalyzed azide–alkyne cycloaddition with a bromo handle for orthogonal chemical attachment. The short PEG4 spacer improves aqueous compatibility and helps reduce steric constraints during bioconjugation workflows. This reagent is frequently used in molecular labeling, surface functionalization, and probe/material assembly where an azide-bearing PEG linker and a secondary reactive group enable modular construction of conjugates.

1. Surface Functionalization

Bromo-PEG4-azide is used to introduce azide functionality onto polymeric and biomaterial surfaces while retaining a bromo group for orthogonal coupling to complementary nucleophiles or surface chemistries. Researchers commonly incorporate it into coating and immobilization strategies for creating stable, click-reactive interfaces for subsequent alkyne-tagged ligands, affinity reagents, or imaging handles. The PEG4 segment supports uniform presentation of the azide group in aqueous environments, which is especially valuable for building reproducible probe densities on microarrays, membranes, and functionalized scaffolds.

2. Biomolecular Conjugation

Bromo-PEG4-azide supports modular bioconjugation workflows where an azide-bearing PEG linker is required to attach biomolecules to imaging tags, detection reagents, or affinity moieties. The bromo functionality provides an additional reactive handle that can be used to pre-functionalize carriers or to tailor conjugate architecture before performing azide–alkyne click labeling with alkyne partners. This design is widely adopted in chemical biology for generating well-defined PEG-linked constructs that improve solubility and spacing between the biomolecule and the appended probe.

3. Molecular Imaging Probes

Bromo-PEG4-azide is applied in the development of azide-functional imaging probes and diagnostic-reagent building blocks that are assembled from alkyne-bearing reporters. The PEG4 linker helps maintain favorable probe behavior in aqueous buffers and supports efficient click-based installation of fluorophores, enrichment tags, or other signal-generating components. Teams developing molecular imaging tools often use this reagent as a versatile intermediate to standardize probe construction across multiple labeling campaigns, enabling rapid exchange of alkyne reporters while keeping the azide-bearing PEG scaffold constant.

4. Diagnostic Reagent Labeling

Bromo-PEG4-azide is used to prepare click-compatible labeling reagents for assay development and analytical workflows that rely on modular attachment of detection components. By providing an azide handle for controlled coupling to alkyne-functional reporters, it enables streamlined generation of reagent conjugates used in research-grade diagnostic and screening formats. The PEG4 spacer is particularly helpful when constructing conjugates that must remain dispersible and accessible for downstream binding or signal generation steps within complex assay mixtures.