Biotin-PEG4-azide (98%)

Name: Biotin-PEG4-azide 

Molecular Formula: C20H36N6O6S 

CAS#: 1309649-57-7 

SMILES: O=C1N[C@]([C@]([H])(CS2)N1)([H])[C@@H]2CCCCC(NCCOCCOCCOCCOCCN=[N+]=[N-])=O 

MDL#: MFCD27977501 

Catalog#: AMTGC893-BT21 

Molecular weight: 488.6 g/mol 

Other names: 

• Azido-PEG4-biotin  

• N-[2-[2-[2-[2-(2-Azidoethoxy)ethoxy]ethoxy]ethoxy]ethyl]biotinamide  

• PEG4 biotin azide  

• Biotinylated PEG4 azide 

Fields of Interest: protein labeling, chemical proteomics, surface functionalization, targeted drug delivery, and molecular imaging 

Background & Applications:  

Background 

Biotin-PEG4-azide (CAS 1309649-57-7) is a heterobifunctional biotinylation and click chemistry reagent that combines a biotin affinity tag, a hydrophilic PEG4 spacer, and a terminal azide group. The biotin moiety enables exceptionally strong and selective binding to streptavidin, avidin, and NeutrAvidin® proteins, while the PEG4 linker improves aqueous solubility, enhances molecular flexibility, and reduces steric hindrance during binding and conjugation events. The terminal azide supports highly efficient bioorthogonal click chemistry, including copper-catalyzed azide–alkyne cycloaddition (CuAAC) and strain-promoted azide–alkyne cycloaddition (SPAAC). This combination of affinity capture and click reactivity makes Biotin-PEG4-azide a versatile tool for bioconjugation, proteomics, diagnostics, chemical biology, and drug discovery applications.  

Applications 

Biotin-PEG4-azide is commonly used in protein labeling, chemical proteomics, surface functionalization, targeted drug delivery, and molecular imaging applications. Typical uses include biotinylation of alkyne-modified proteins, peptides, oligonucleotides, polymers, and nanoparticles through click chemistry, enabling subsequent purification, enrichment, detection, or immobilization using streptavidin-based systems. The PEG4 spacer improves accessibility of the biotin group and minimizes steric interference during binding events. Biotin-PEG4-azide has also been utilized in the preparation of PROTAC-related constructs, affinity probes, diagnostics, and advanced biomaterials where both bioorthogonal conjugation and high-affinity biotin capture are desired. 

Appearance: White, waxy solid 

Purity: 98% 

Storage: Room Temperature 

Solubility: Solubility is poor in most organic solvents. Sparingly soluble in water. 

Literature:  

• Tetrahedron Letters, 2016, vol. 57, # 22, p. 2406 – 2409 

• Chemical Record, 2019, vol. 19, # 12, p. 2362 – 2369 

• Advanced Synthesis and Catalysis, 2023, vol. 365, # 13, p. 2171 – 2176