N-(Azido-PEG2)-N-Boc-PEG3-NHS ester | CAS 2093153-85-4

N-(Azido-PEG2)-N-Boc-PEG3-NHS ester is a bifunctional, PEG-based click chemistry reagent that combines an azide handle for bioorthogonal conjugation with an NHS ester for efficient coupling to primary amines on proteins, peptides, and other amine-bearing biomolecules. The structure typically features multiple PEG segments that enhance aqueous solubility and reduce nonspecific interactions, making it well suited for constructing stable PEGylated conjugates and modular labeling reagents. Its azide functionality enables downstream strain-promoted or copper-catalyzed azide–alkyne click chemistry workflows, while the NHS ester supports straightforward attachment to targeting ligands, scaffolds, and imaging components.

1. Protein PEGylation Handles

N-(Azido-PEG2)-N-Boc-PEG3-NHS ester is widely used to introduce a defined azide-functional PEG spacer onto proteins and peptides via NHS-amine coupling, generating conjugates that can be further diversified through click chemistry. Researchers commonly select this reagent when they need improved solubility, reduced aggregation, and a clickable attachment point for attaching fluorophores, affinity tags, or other functional moieties. The PEG architecture helps maintain conjugate stability in aqueous buffers and supports subsequent conjugation workflows for analytical and imaging studies.

2. Targeting Ligand Conjugation

N-(Azido-PEG2)-N-Boc-PEG3-NHS ester supports modular preparation of clickable targeting constructs by coupling the NHS ester to amine groups on antibodies, antibody fragments, receptor-binding ligands, or other recognition elements. After coupling, the azide handle enables orthogonal attachment of imaging probes, enrichment handles, or polymeric components using established azide–alkyne click strategies. This approach is particularly valuable in molecular imaging reagent development and chemical biology tool creation, where consistent spacer length and aqueous compatibility can improve labeling reproducibility across batches.

3. Surface and Material Functionalization

N-(Azido-PEG2)-N-Boc-PEG3-NHS ester is used to functionalize biomaterials and surfaces that present accessible primary amines, including amine-derivatized polymers, hydrogels, and coating layers on labware. By installing azide-PEG linkers through NHS coupling, the reagent creates clickable interfaces that can be patterned or sequentially modified with complementary alkyne-bearing molecules. Such workflows are common in materials chemistry and diagnostic reagent development, where controlled surface chemistry is required to attach capture ligands, reporters, or affinity components while maintaining hydration and minimizing nonspecific adsorption.

4. Multi-Step Probe Assembly

N-(Azido-PEG2)-N-Boc-PEG3-NHS ester is frequently employed as an intermediate building block for assembling multi-component chemical probes, where an initial NHS coupling step installs the azide-PEG functionality and later click chemistry attaches the final reporter or targeting module. This design supports flexible probe architectures for fluorescence labeling, enrichment strategies, and affinity-based detection tool development. The reagent’s PEG spacing is often selected to tune accessibility of the azide group, helping ensure efficient downstream conjugation to alkyne-functional partners under typical labeling conditions.