1-Isothiocyanato-PEG3-azide | CAS 1310686-23-7

1-Isothiocyanato-PEG3-azide is a heterobifunctional PEG-based click chemistry reagent that combines an isothiocyanate electrophile with a terminal azide for copper-free or copper-mediated azide–alkyne cycloaddition workflows. The short PEG3 spacer provides aqueous compatibility and spacing control between the bioconjugation handle and the azide “click” functionality. This reagent is commonly used in chemical biology and biomaterials research to introduce azide groups onto proteins, peptides, and polymer surfaces, enabling subsequent labeling, immobilization, and modular assembly of imaging or functional components.

1. Protein Azide Labeling

1-Isothiocyanato-PEG3-azide is widely used to install azide handles onto amine-containing biomolecules such as antibodies, enzymes, and affinity reagents for downstream click-based conjugation. The isothiocyanate group reacts under standard bioconjugation conditions with primary amines to form stable thiourea linkages, while the PEG3 spacer helps reduce steric congestion around the azide. Researchers then use the resulting azide-functional proteins to attach fluorophores, affinity tags, or other molecular probes through azide–alkyne coupling, supporting workflows in proteomics sample preparation, imaging reagent construction, and assay development where modular reactivity is required.

2. Surface Functionalization

1-Isothiocyanato-PEG3-azide supports azide introduction onto biomaterial surfaces and coatings that contain accessible amine groups, including functionalized polymer films, hydrogel matrices, and derivatized nanoparticles. By leveraging the isothiocyanate reactivity toward surface amines, the reagent enables controlled incorporation of azide moieties that can later be addressed with complementary alkyne-bearing ligands, crosslinkers, or imaging handles. This approach is frequently adopted in materials chemistry and molecular imaging tool development to create platforms with defined clickable sites for immobilizing capture molecules, tuning surface chemistry, or building multicomponent assemblies without requiring direct modification of the final functional ligands.

3. PEG Linker Building Blocks

1-Isothiocyanato-PEG3-azide is used as a practical PEG3 linker building block to create conjugates with improved solubility and spacing between a biorecognition element and a clickable attachment point. The PEG3 segment helps maintain aqueous processability and can reduce non-specific interactions that sometimes arise when azide groups are installed directly onto densely functionalized scaffolds. In chemical biology and diagnostics reagent development, this linker strategy is commonly applied to prepare azide-tagged reagents for subsequent coupling to alkynes used in labeling panels, multivalent binding constructs, and modular assay components, where consistent linker length and water compatibility are important for reproducible reagent behavior.

4. Molecular Imaging Probe Assembly

1-Isothiocyanato-PEG3-azide is employed to generate azide-functional intermediates for assembling molecular imaging probes that require a modular “click” step. After azide installation onto a targeting scaffold or carrier (for example, an azide-tagged protein, peptide conjugate, or polymeric construct), the probe is completed by coupling to alkyne-bearing imaging reporters such as fluorescent dyes, bioluminescent tags, or other optical/molecular imaging moieties. The PEG3 spacer and the orthogonal azide handle facilitate reliable downstream conjugation, enabling probe libraries where the targeting component and the reporter component can be exchanged to optimize labeling density and construct architecture for research imaging applications.