Azido-PEG24-NHS ester | CAS 1108750-59-9

Azido-PEG24-NHS ester is a polyethylene glycol (PEG)-based azide functional reagent that combines an NHS ester for efficient amide coupling with primary amines and a terminal azide handle for subsequent strain-promoted or copper-catalyzed azide–alkyne click chemistry. The long, flexible PEG spacer (24 ethylene glycol units) is commonly used to improve solubility, reduce nonspecific interactions, and provide distance between biomolecular surfaces and reactive partners. This bifunctional design makes Azido-PEG24-NHS ester widely relevant for preparing clickable bioconjugates used in chemical biology, molecular imaging workflows, and advanced materials functionalization.

1. Antibody And Protein Labeling

Azido-PEG24-NHS ester is frequently used to install a click-ready azide handle onto antibodies, enzymes, and other amine-bearing proteins via NHS-ester coupling to lysine residues or N-termini. The PEG spacer helps maintain colloidal stability and can reduce steric crowding that would otherwise limit downstream conjugation efficiency. Researchers commonly use the resulting azide-functionalized bioconjugates as versatile intermediates for attaching fluorophores, affinity tags, or polymeric components through click chemistry, enabling modular probe construction for assay development and imaging reagent preparation.

2. Surface Coating And Biomaterials

Azido-PEG24-NHS ester is applied to functionalize biomaterial surfaces and scaffold materials that present accessible amine groups, including modified polymers, hydrogel components, and coating layers used in biosensor and materials research. By introducing azide functionality with a hydrophilic PEG spacer, the reagent supports subsequent attachment of alkyne-bearing ligands, crosslinkers, or reporter molecules while helping to limit nonspecific adsorption. This approach is commonly adopted when researchers need stable, chemically defined clickable interfaces for building multilayer coatings, patterned materials, or reusable platforms for diagnostic reagent development.

3. Imaging Probe And Reporter Assembly

Azido-PEG24-NHS ester serves as a key building block for constructing imaging and detection reporters that rely on azide–alkyne click conjugation. After coupling to an amine-containing targeting scaffold or carrier (such as a protein, peptide, or polymeric backbone), the installed azide enables rapid, high-selectivity labeling with alkyne-functional dyes, imaging moieties, or enrichment handles under click-compatible conditions. The extended PEG chain can improve probe behavior in complex assay matrices by enhancing water compatibility and moderating local microenvironment effects around the conjugation site.

4. Enzyme Activity And Assay Reagents

Azido-PEG24-NHS ester is commonly used in chemical biology to generate azide-tagged enzyme conjugates and enzyme-associated reagents for downstream click-based modular assembly. Amine-reactive NHS chemistry allows incorporation of the azide handle onto enzymes and other catalytic proteins, while the PEG spacer provides flexibility that can help preserve functional accessibility of the active or binding regions. These azide-functional enzyme constructs are then used as intermediates to attach substrates, detection reporters, or immobilization chemistries, supporting the creation of customizable assay components and research tools for mechanistic studies and platform optimization.