Azido-PEG3-S-PEG3-azide | CAS 2055023-77-1

Azido-PEG3-S-PEG3-azide is a PEG-based, bifunctional click chemistry crosslinker featuring two terminal azide groups separated by short PEG3 spacers and a central thioether linkage. As a versatile azide building block for strain-promoted or copper-catalyzed azide–alkyne cycloaddition workflows, it is commonly selected to introduce defined, flexible handles for modular conjugation and surface/material functionalization. Its symmetrical, water-compatible architecture makes it well suited for constructing multivalent bioconjugates, tuning linker length, and generating well-defined crosslinked networks in chemical biology and biomaterials research.

1. Multivalent Bioconjugation

Azido-PEG3-S-PEG3-azide is widely used to build multivalent conjugates where two independent azide-reactive sites are required to attach to complementary alkyne-functional partners, such as cyclooctyne/alkyne-bearing targeting ligands, biomolecule scaffolds, or probe carriers. Researchers often employ this reagent to increase effective local concentration and to create controlled spacing between conjugation points, which is particularly valuable when preparing fluorescent labeling reagents, affinity probes, and assay components that benefit from multivalent presentation. The PEG3 spacers help maintain solubility and reduce steric congestion around the reactive termini, supporting consistent coupling across complex biomolecular mixtures.

2. Surface And Hydrogel Functionalization

Azido-PEG3-S-PEG3-azide is commonly incorporated into surface modification and biomaterial workflows to introduce azide functionality for subsequent click attachment of biomolecules, coatings, or capture chemistries. In hydrogel and polymer network engineering, the reagent can serve as a linker element that enables post-fabrication functionalization, allowing researchers to tune the density and distribution of reactive sites without changing the bulk material chemistry. Its bifunctional design supports crosslinking strategies in which alkyne-bearing crosslinkers or functional moieties are coupled to create mechanically or chemically addressable materials used for biosensing, cell-interaction studies, and advanced materials platform development.

3. Molecular Imaging Probe Assembly

Azido-PEG3-S-PEG3-azide is used in molecular imaging and chemical biology tool development to assemble modular probe constructs from alkyne-functional imaging reporters and targeting or localization elements. The reagent’s two azide termini enable controlled, stepwise assembly of multicomponent imaging reagents, including fluorescent and luminescent labeling systems and imaging-compatible conjugates used in imaging assay development. By providing flexible PEG3 spacing between attachment points, Azido-PEG3-S-PEG3-azide helps preserve the accessibility of imaging reporters and targeting motifs, supporting robust probe construction for downstream experimental workflows.

4. Diagnostic Reagent And Assay Platforms

Azido-PEG3-S-PEG3-azide is frequently selected for diagnostic reagent development and assay platform construction where defined linker geometry and modular coupling are required. The reagent enables azide-based incorporation into assay-ready materials such as bead-based reagents, microarray surfaces, and affinity capture formats, followed by click coupling to alkyne-functional detection elements or secondary reagents. Its symmetrical bifunctionality supports reproducible conjugation architectures, which is advantageous when standardizing reagent performance across batches and when designing multiplexed assay components that require consistent spacing between binding and reporting domains.