Propargyl-PEG4-acid | CAS 1415800-32-6

Propargyl-PEG4-acid is a PEG-based alkyne-bearing linker designed for bioorthogonal click chemistry workflows, most commonly as a terminal alkyne partner in copper-catalyzed azide–alkyne cycloaddition (CuAAC) and related conjugation strategies. Its flexible PEG4 spacer and carboxylic acid functionality support aqueous compatibility and straightforward coupling into larger biomolecule or material platforms. As a research-grade click handle, Propargyl-PEG4-acid is widely used to introduce an alkyne “tag” for subsequent attachment to azide-functional probes, surfaces, or polymeric constructs in chemical biology and molecular imaging reagent development.

1. Bioconjugation Linker Use

Propargyl-PEG4-acid is frequently employed as a modular PEG linker to functionalize biomolecules, enabling downstream attachment to azide-bearing partners such as fluorescent dyes, affinity ligands, or affinity handles used in target labeling workflows. The carboxylic acid group allows incorporation into activated ester or amide-forming chemistries, while the terminal alkyne provides a robust click handle for rapid conjugation to azide-functional reagents. This combination is particularly valuable when researchers need improved solubility, reduced nonspecific interactions, and a controllable spacing between the biomolecule and the appended reporter or capture moiety.

2. Fluorescent Probe Assembly

Propargyl-PEG4-acid is well suited for building fluorescent and imaging probes where an alkyne-bearing intermediate is required to connect to azide-functional fluorophores or quencher systems. In probe generation pipelines, the PEG4 spacer helps maintain aqueous dispersibility and can mitigate steric constraints that otherwise limit labeling efficiency. By using Propargyl-PEG4-acid as the click-compatible scaffold, teams can standardize probe construction across multiple targets, swapping azide partners while keeping the same alkyne-bearing backbone for consistent reagent handling.

3. Surface and Material Functionalization

Propargyl-PEG4-acid is commonly used to introduce clickable alkyne functionality onto polymeric materials, hydrogels, and prepared surfaces prior to immobilization of azide-tagged biomolecules or detection reagents. The PEG spacer supports better wetting and minimizes harsh local environments at the interface, which is advantageous for creating reproducible functional coatings and patterned binding layers. Researchers in biomaterials science and diagnostic reagent development often rely on Propargyl-PEG4-acid to create stable, modular surfaces that can be rapidly “decorated” with azide-functional components through click conjugation.

4. Molecular Imaging Reagent Building

Propargyl-PEG4-acid is used as a linker for constructing molecular imaging reagent components that require orthogonal modular assembly, typically by pairing the terminal alkyne with azide-functional imaging tags or targeting motifs. The PEG4 chain provides a hydrophilic, flexible separation between the imaging moiety and the conjugation site, which can be important for maintaining solubility and minimizing unfavorable interactions during reagent preparation. In molecular imaging and chemical biology laboratories, Propargyl-PEG4-acid enables streamlined synthesis of probe libraries by allowing azide-tag exchange while keeping a consistent alkyne-bearing precursor.