Propargyl-PEG4-CH2-acid | CAS 1872433-74-3

Propargyl-PEG4-CH2-acid is a PEG-based alkyne-bearing carboxylic acid designed for copper-free and copper-mediated click chemistry workflows, where the terminal propargyl group serves as the reactive handle for conjugation. Its flexible PEG spacer and acid functionality make it well suited for solubilization, surface coupling, and incorporation into polymeric or biomolecular constructs. As a research-grade click reagent, it is commonly used to introduce alkyne functionality into imaging probes, material scaffolds, and bioorthogonal labeling strategies.

1. Bioorthogonal Surface Functionalization

Propargyl-PEG4-CH2-acid is widely used to functionalize surfaces and interfaces with alkyne groups for subsequent click-based attachment of fluorescent tags, affinity ligands, or macromolecular coatings. The PEG spacer helps reduce nonspecific interactions and improves accessibility of the clickable alkyne on dense material surfaces, which is valuable in workflows such as coating microplates, modifying hydrogel components, and preparing functionalized sensor surfaces. The carboxylic acid handle also supports robust coupling to activated surfaces or polymer backbones, enabling stable incorporation of the alkyne motif into materials used for assay development and materials characterization.

2. PEG-Linker Conjugation Platforms

Propargyl-PEG4-CH2-acid serves as a practical PEG linker building block for assembling conjugation platforms where controlled spacing between functional domains is important. Researchers use it to incorporate an alkyne “landing pad” into larger constructs including polymer conjugates, nanoparticle surface chemistries, and multicomponent reagent libraries that later undergo click reactions with complementary azide-bearing partners. The PEG4 length is particularly useful for minimizing steric hindrance and maintaining solubility in aqueous labeling buffers, supporting downstream conjugation workflows in chemical biology and molecular imaging reagent development.

3. Molecular Imaging Probe Assembly

Propargyl-PEG4-CH2-acid is commonly employed in the construction of molecular imaging and detection probes that require modular attachment of fluorophores, affinity reporters, or imaging moieties via click chemistry. By providing a defined alkyne functionality separated by a flexible PEG spacer, the reagent enables efficient post-labeling strategies that are compatible with probe assembly pipelines used in research laboratories. The carboxylic acid functionality further supports incorporation into probe scaffolds or linker systems, allowing investigators to tailor probe architecture for improved handling in labeling and purification workflows.

4. Polymer and Hydrogel Crosslinking

Propargyl-PEG4-CH2-acid is used to introduce clickable alkyne groups into polymer and hydrogel formulations for crosslinking or stepwise functionalization with azide-containing crosslinkers and functional components. In biomaterials research, the PEG spacer supports homogeneous distribution of reactive sites and can help tune the effective spacing between crosslink points, which is relevant when preparing materials for microscopy-based studies, surface patterning, and materials characterization. The reagent’s carboxylic acid group enables convenient incorporation into polymer backbones or pendant side chains, supporting reproducible construction of click-enabled material systems.