N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester | CAS 2100306-76-9

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester is a biotin-functionalized azide-containing PEG reagent designed for copper-free or copper-assisted azide–alkyne click chemistry workflows. The molecule combines an azide handle for selective conjugation with a biotin moiety for high-affinity streptavidin/avidin capture, while the PEG spacers improve aqueous solubility and reduce steric effects during labeling and immobilization. This reagent is commonly used to generate biotinylated probes, affinity reagents, and clickable surfaces for molecular imaging, diagnostics development, and biomaterials research.

1. Streptavidin-Based Probe Labeling

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester is widely used to prepare clickable biotinylated probes for downstream binding to streptavidin or avidin reagents in assay development and analytical workflows. Researchers incorporate the reagent into azide–alkyne labeling schemes to introduce a biotin capture tag onto antibodies, peptides, nucleic-acid probes, or other targeting ligands, enabling modular assembly of complex detection constructs. The PEG architecture helps maintain probe performance in aqueous buffers and supports consistent immobilization on streptavidin-coated plates, beads, and biosensor surfaces.

2. Clickable Surface Functionalization

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester is a practical building block for creating biotin-enabled, click-reactive materials used in biosensing, affinity capture platforms, and extracellular-matrix mimetic systems. By installing the azide functionality and a biotin handle on the same construct, the reagent supports two-stage workflows: first, immobilize or organize the material via biotin–avidin interactions, and then attach additional molecular components through click chemistry. This dual functionality is particularly valuable when researchers need stable surface presentation combined with orthogonal coupling to fluorescent dyes, affinity ligands, or other reporter modules.

3. Molecular Imaging and Tracking Reagents

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester is used to generate biotin-tagged imaging and tracking reagents that can be assembled with alkyne-bearing reporters such as fluorophores, quencher pairs, or imaging moieties. In molecular imaging and chemical biology tool development, the reagent offers a convenient way to introduce a clickable azide for conjugation while preserving strong biotin-mediated capture for enrichment, wash-based cleanup, or standardized immobilization on imaging-compatible platforms. PEG spacing supports homogeneous labeling and helps minimize nonspecific interactions that can arise from densely functionalized biomolecules.

4. Diagnostic Reagent and Assay Platforms

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester supports the construction of diagnostic reagent components where biotin capture and click-based modularity are advantageous for consistent assay assembly. Assay developers use the reagent to prepare azide-functional biotin conjugates that can be coupled to detection elements, secondary binding partners, or signal reporters bearing complementary alkyne functionalities. The methyl ester and PEG linkers are leveraged to facilitate incorporation into labeling workflows that require robust aqueous handling and controlled presentation of the biotin tag for reliable streptavidin/avidin-based format compatibility.

5. Biomaterials Crosslinking and Immobilization

N-(Azido-PEG3)-N-Biotin-PEG4-methyl ester is applied in biomaterials science to create immobilized, biotin-functional constructs that can be further decorated through azide–alkyne click chemistry. Researchers use it to anchor biomolecules or functional polymers onto streptavidin-coated scaffolds, enabling stepwise fabrication of composite materials, affinity capture matrices, and biointerface coatings. The PEG spacers help maintain accessibility of both the azide and biotin groups, which is important for reproducible coupling density and for maintaining binding-site availability in complex experimental environments.