Propargyl-PEG4-thiol | CAS 1347750-80-4

Propargyl-PEG4-thiol is a bifunctional PEG-based linker that combines a terminal alkyne for copper-free or copper-mediated click chemistry with a thiol handle for conjugation and surface immobilization. As a PEGylated propargyl thioether/thiol-bearing reagent, it is commonly used to introduce flexible, water-soluble spacers between biomolecules, polymers, and solid supports while enabling subsequent attachment through click-compatible functional groups. Its modular design makes it a practical building block for preparing clickable conjugates, functional coatings, and imaging or assay materials where controlled tether length and conjugation density are important.

1. Bioconjugation Linkers

Propargyl-PEG4-thiol is widely used as a spacer linker in bioconjugation workflows to connect thiol-reactive surfaces or thiol-bearing biomolecules to alkyne-tagged partners for downstream click coupling. Researchers in chemical biology and biomaterials routinely employ the PEG4 chain to reduce steric hindrance and improve aqueous handling during conjugate assembly, particularly when attaching probes, affinity reagents, or labeling handles to proteins, peptides, and other macromolecular targets. The thiol functionality supports straightforward attachment to maleimide- or thiol-reactive chemistries and enables stable tethering strategies that preserve accessibility of the terminal alkyne for subsequent click steps.

2. Surface Functionalization Coatings

Propargyl-PEG4-thiol is used to functionalize sensor chips, microarrays, and material surfaces that rely on thiol-based immobilization followed by click-based presentation of reactive handles. In materials science and diagnostics reagent development, the PEG4 spacer helps create a hydrated interface that can improve accessibility of immobilized ligands and reduce nonspecific interactions compared with shorter linkers. After surface anchoring through the thiol group, the terminal alkyne provides a convenient click-compatible site for attaching fluorescent tags, affinity molecules, or other reporter components to generate patterned, multicomponent surfaces.

3. Molecular Imaging Probe Assembly

Propargyl-PEG4-thiol serves as a practical intermediate for building molecular imaging probes and fluorescent labeling reagents that require both a conjugation handle and a click-ready moiety. Chemical biology groups use the PEG4-thiol/alkyne combination to construct probe architectures where the flexible spacer supports efficient labeling and maintains probe solubility in complex assay buffers. The reagent’s click-compatible alkyne enables modular incorporation of dyes, imaging reporters, or targeting motifs, while the thiol functionality supports attachment to carrier scaffolds, linkers, or pre-functionalized probe platforms used in fluorescence-based and imaging-oriented research.

4. Polymer and Hydrogel Crosslinking

Propargyl-PEG4-thiol is commonly incorporated into polymer and hydrogel material design to create clickable networks and to introduce defined reactive sites for post-fabrication functionalization. Biomaterials researchers use the PEG4 spacer to tune mechanical and swelling properties while maintaining chemical accessibility of the terminal alkyne for subsequent coupling with complementary click partners. Thiol-based incorporation strategies allow the reagent to be integrated into polymer backbones, crosslinker systems, or surface-grafted layers, enabling later attachment of bioactive ligands, imaging tags, or analytical reporters through click chemistry without requiring extensive reprocessing of the bulk material.