Propargyl-PEG4-sulfonic acid | CAS 1817735-29-7

Propargyl-PEG4-sulfonic acid is a PEG-based alkyne building block that incorporates a terminal propargyl (alkyne) handle for click chemistry and a sulfonic acid functional group for aqueous compatibility and ionic stabilization. As a reagent for copper-catalyzed azide–alkyne cycloaddition (CuAAC), it is commonly used to introduce a flexible, hydrophilic linker to biomolecule conjugates, polymer materials, and imaging/diagnostic scaffolds. The PEG4 spacer and sulfonate group help maintain solubility and reduce non-specific interactions during downstream labeling workflows, making it a practical component for constructing alkyne-functional probes and linkers.

1. Biomolecule Conjugation Linkers

Propargyl-PEG4-sulfonic acid is widely used to install an alkyne handle onto proteins, peptides, and other biomolecular platforms that are subsequently functionalized via CuAAC. Its PEG4 spacer provides conformational flexibility that can improve accessibility of the reactive group in crowded biological conjugation settings, while the sulfonic acid enhances water solubility for labeling workflows carried out in aqueous buffers. Researchers use this reagent to generate alkyne-bearing intermediates for downstream attachment of azide-functional tags, affinity handles, or reporter moieties, supporting modular assembly of bioconjugates for biochemical assays, proteomics sample preparation, and surface-based binding studies.

2. Surface Immobilization Chemistry

Propargyl-PEG4-sulfonic acid serves as a useful alkyne-containing linker for preparing functional surfaces and material interfaces that require subsequent azide–alkyne coupling. The sulfonic acid functionality supports dispersion and wetting in aqueous processing steps, which is valuable when immobilizing reactive linkers onto hydrophilic coatings, polymer films, or hydrogel-like substrates. By incorporating this reagent into surface modification strategies, laboratories can create stable, spatially accessible alkyne sites that can be patterned or uniformly labeled using azide-bearing biomolecules, dyes, or capture ligands, enabling reproducible construction of functional diagnostic and research surfaces.

3. Molecular Imaging Probe Building

Propargyl-PEG4-sulfonic acid is commonly employed as a linker component in the synthesis of imaging-related probes where an alkyne handle is required for late-stage CuAAC conjugation. The PEG4 chain helps tune hydrophilicity and steric presentation of the conjugation site, which can be advantageous when attaching fluorophores, affinity reporters, or other imaging tags that must remain accessible after conjugation. In molecular imaging reagent development, this reagent is frequently used to generate alkyne-functional probe intermediates that can be rapidly diversified by coupling to azide-modified reporter constructs, streamlining probe library generation for research instrumentation and optical/chemosensing applications.

4. Diagnostic Reagent and Assay Platforms

Propargyl-PEG4-sulfonic acid is used to prepare alkyne-functional components for diagnostic reagent development and assay platform construction, particularly where modular coupling to azide-labeled reagents is desired. The PEG4 spacer and sulfonate group support aqueous handling and can help maintain consistent conjugation performance during reagent formulation and assay assembly. Many workflows rely on this reagent to introduce a controlled, hydrophilic linker between a reactive biomolecular recognition element and a downstream azide-bearing detection or capture moiety, supporting scalable preparation of assay reagents used in research-grade testing formats and analytical method development.