Azido-PEG5-Br | CAS 1402411-90-8

Azido-PEG5-Br is a bifunctional polyethylene glycol (PEG) linker bearing an azide group and a terminal bromide, enabling orthogonal chemical handles for downstream conjugation workflows. As a click chemistry reagent, the azide moiety is commonly used for copper-catalyzed azide–alkyne cycloaddition (CuAAC) to connect biomolecules, polymers, or surfaces to alkyne-bearing partners. The PEG5 spacer provides hydrophilicity and spacing that can reduce steric constraints during labeling, coating, and probe assembly, while the bromide offers an additional functional outlet for nucleophilic substitution or surface attachment strategies in material and assay development.

1. Bioconjugation Via CuAAC

Azido-PEG5-Br is widely used to install an azide handle on proteins, peptides, antibodies, and other biomolecular scaffolds so they can be coupled to alkyne-functional probes, tags, or imaging reporters through CuAAC. The PEG5 segment helps maintain accessibility of the azide during conjugation, which is particularly valuable when working with bulky targeting ligands or multivalent labeling schemes. Researchers frequently choose this reagent when they need a single PEG-based linker that supports reliable click labeling while also retaining a secondary reactive bromide for further derivatization or controlled attachment to carrier materials.

2. Surface Patterning And Coatings

Azido-PEG5-Br supports the construction of functional surfaces and thin films where azide groups are required for subsequent click immobilization of alkyne-bearing biomolecules, affinity ligands, or fluorescent reporters. The PEG spacer can improve antifouling behavior and reduce nonspecific adsorption compared with shorter linkers, making it a common choice for assay surfaces, biosensor interfaces, and microarray formats. The bromide functionality can further assist in anchoring or post-modification steps, enabling practical workflows for creating patterned chemistries on polymeric or functionalized substrates prior to click-based capture.

3. Molecular Imaging Probe Assembly

Azido-PEG5-Br is used as a linker intermediate for assembling imaging and detection probes that rely on azide–alkyne click chemistry to connect targeting motifs with fluorophores, enrichment handles, or reporter scaffolds. The PEG5 chain provides a flexible spacer that can help preserve optical labeling performance and reduce steric interference between the probe components after conjugation. In probe development pipelines, this reagent is frequently selected to standardize linker length and hydrophilicity across libraries of alkyne-functional imaging reagents, facilitating consistent probe construction for research-grade molecular imaging studies.

4. Polymer And Hydrogel Functionalization

Azido-PEG5-Br is employed to introduce azide functionalities into polymers, crosslinkable networks, and hydrogel systems so that alkyne-bearing components can be incorporated via click coupling. The PEG5 linker is particularly useful for tuning local spacing and water compatibility in material formulations, which can influence how functional groups are presented within a matrix. Product developers and materials researchers often use Azido-PEG5-Br to generate modular, post-functionalizable materials where click chemistry provides a robust route to attach signaling moieties, affinity tags, or analytical reporters without relying on less selective coupling chemistries.