Propargyl-PEG4-CH2-methyl ester | CAS 1872433-63-0

Propargyl-PEG4-CH2-methyl ester is a PEG-based, alkyne-bearing click chemistry reagent designed for bioorthogonal conjugation workflows. As a propargyl ester, it provides a terminal alkyne handle for copper-catalyzed azide–alkyne cycloaddition (CuAAC) and a methyl ester functionality that can support downstream derivatization of the PEG terminus. Its flexible PEG4 spacer improves aqueous compatibility and helps reduce steric constraints during labeling, making it well suited for research-grade probe, surface, and material conjugation where controlled attachment chemistry is required.

1. Fluorescent Probe Conjugation

Propargyl-PEG4-CH2-methyl ester is commonly used to prepare azide-reactive labeling intermediates for fluorescence-based detection platforms. Researchers incorporate the PEG4–alkyne motif to attach dyes, imaging tags, or quencher–dye pairs to biomolecules such as proteins, peptides, and targeting ligands via CuAAC, enabling modular assembly of multicomponent probes. The PEG spacer is particularly valued when maintaining solubility and minimizing nonspecific interactions during conjugate preparation for microscopy, flow cytometry, or plate-based assay development.

2. Biomolecule PEGylation Linker

Propargyl-PEG4-CH2-methyl ester is frequently selected as a PEGylation linker building block for constructing conjugates that require a defined distance between a reactive biomolecule and an added functional group. By introducing the propargyl alkyne through CuAAC-compatible chemistry, teams can generate site-specific attachment points to azide-bearing partners while leveraging the PEG4 chain to improve aqueous handling and conformational flexibility. The methyl ester terminus also supports iterative functionalization strategies in labeling pipelines, where the PEG terminus must be converted into a desired reactive handle before final coupling.

3. Surface and Material Functionalization

Propargyl-PEG4-CH2-methyl ester is widely applied in materials chemistry to introduce click-ready alkyne functionality onto polymer surfaces, coatings, and scaffold materials. In typical workflows, the PEG4–alkyne reagent is immobilized or incorporated during surface modification, then reacted with azide-functional components to create patterned or functionalized interfaces for biosensing and materials research. The PEG spacer helps maintain accessibility of the alkyne for subsequent CuAAC steps, supporting robust coupling of imaging reagents, affinity ligands, or reporter molecules onto otherwise heterogeneous material substrates.

4. Molecular Imaging Reagent Building

Propargyl-PEG4-CH2-methyl ester is used as a modular reagent for assembling molecular imaging tools that require an alkyne handle for rapid conjugation to azide-bearing imaging moieties. Chemical biology groups often rely on PEG4 linkers to tune solubility and reduce steric hindrance, which is beneficial when constructing complex probe architectures such as multivalent imaging constructs and signal-amplified labeling reagents. The propargyl ester format supports iterative build strategies, allowing researchers to incorporate the alkyne functionality early and complete the final imaging conjugation through CuAAC-compatible coupling with azide-tagged components.