Azido-PEG3-aminoacetic acid-NHS ester | CAS 2170240-91-0

Azido-PEG3-aminoacetic acid-NHS ester is a heterobifunctional PEG-based linker that combines an NHS ester for efficient amide coupling with primary amines and a terminal azide handle for subsequent copper-free or copper-mediated click chemistry. The short, flexible PEG3 spacer and the aminoacetic acid motif help balance reactivity and solubility, making the reagent well suited for building modular bioconjugates. This design is commonly used to introduce a clickable azide to proteins, peptides, and biomaterial surfaces prior to downstream labeling, immobilization, or probe assembly.

1. Protein Labeling Workflows

Azido-PEG3-aminoacetic acid-NHS ester is widely used to functionalize proteins and peptides by installing an azide-bearing PEG spacer onto lysine residues or N-terminal amines via NHS ester chemistry. Researchers rely on this approach to generate azide-modified biomolecules that can be carried into subsequent click steps for attaching fluorophores, affinity tags, or imaging moieties while maintaining a controlled linker length and improved aqueous compatibility. The azide functionality enables orthogonal conjugation strategies that integrate cleanly with established click chemistry pipelines used in chemical biology and translational research tool development.

2. Surface Immobilization And Coatings

Azido-PEG3-aminoacetic acid-NHS ester supports azide introduction onto amine-functionalized surfaces, including polymer films, hydrogel matrices, and microarray substrates, where NHS ester reactivity can be used to tether the linker to available surface amines. This creates a clickable interface for later coupling of biomolecules, capture ligands, or reporter constructs through azide-reactive click partners. In biomaterials science workflows, the PEG3 spacer helps reduce steric crowding at the surface and can improve accessibility of the reactive handle for subsequent immobilization and assay assembly.

3. Molecular Imaging Probe Assembly

Azido-PEG3-aminoacetic acid-NHS ester is frequently incorporated into probe-building workflows where a clickable azide is required for assembling imaging reagents with defined attachment points. By first conjugating the NHS ester to a targeting scaffold such as a protein, peptide, or polymer carrier, the resulting azide-modified intermediate can be reacted with complementary cyclooctyne or alkyne-containing imaging components using click chemistry-compatible conditions. This modular strategy is attractive for generating libraries of labeled probes with consistent linker architecture, supporting efficient optimization of labeling density and conjugate design in molecular imaging research.

4. Diagnostic Reagent And Assay Development

Azido-PEG3-aminoacetic acid-NHS ester is used to prepare azide-functional conjugates that serve as building blocks for diagnostic reagent formats, including affinity-based detection systems and assay reagents that require modular coupling. The NHS ester enables rapid installation of the azide handle onto amine-bearing components, which can then be clicked to reporter groups, signal amplifiers, or capture elements depending on the assay architecture. Such workflows benefit from the PEG3 spacing and the aminoacetic acid segment, which help maintain solubility and reduce nonspecific interactions during reagent preparation and assay handling.