Propargyl-PEG2-COOtBu | CAS 1807503-80-5

Propargyl-PEG2-COOtBu is a PEG-based propargyl ester building block designed for copper-free or copper-catalyzed click chemistry workflows, where the terminal alkyne serves as a versatile handle for bioorthogonal conjugation. The reagent combines a short, hydrophilic PEG spacer with a protected carboxylic acid (tBu ester), enabling downstream deprotection or further functionalization while maintaining solubility and reduced nonspecific interactions. This structure is commonly used to introduce clickable linkers into biomolecule conjugates, polymer materials, and imaging/diagnostic platforms that require controlled spacing and stable tethering.

1. Bioconjugation Linkers

Propargyl-PEG2-COOtBu is widely used as a PEGylated clickable linker for preparing alkyne-bearing intermediates in protein, peptide, and nucleic-acid conjugation pipelines. Researchers incorporate the PEG spacer to improve aqueous solubility and to tune the effective distance between a target biomolecule and a downstream cargo such as a fluorophore, affinity tag, or polymeric scaffold. The protected carboxylate functionality supports controlled coupling strategies after deprotection, allowing the same reagent to contribute both a click handle and a chemically addressable site for subsequent attachment steps.

2. Fluorophore and Imaging Probes

Propargyl-PEG2-COOtBu supports the construction of alkyne-functional imaging reagents by providing a hydrophilic PEG tether that helps maintain probe dispersibility and reduces aggregation in labeling buffers. In molecular imaging and chemical biology research, the reagent is frequently used to generate clickable probe precursors that can be coupled to azide-modified dyes, affinity reporters, or targeting ligands using established click conjugation workflows. The tBu-protected carboxyl group offers a practical handle for later derivatization, which is valuable when probe architectures require specific attachment geometries or multicomponent assembly.

3. Surface and Polymer Functionalization

Propargyl-PEG2-COOtBu is applicable to materials chemistry efforts where clickable PEG linkers are needed to functionalize surfaces and polymer networks. The terminal alkyne enables post-modification attachment to azide-functional coatings, beads, or patterned substrates, while the PEG spacer improves wetting and helps mitigate nonspecific adsorption on hydrophilic materials. The protected carboxylate can be leveraged for further chemistry after deprotection, supporting the creation of multivalent materials such as clickable hydrogels, functional coatings, and linker-rich polymer conjugates used in assays and materials-based screening.

4. Diagnostic Reagent Building Blocks

Propargyl-PEG2-COOtBu is commonly employed in the development of diagnostic research reagents that rely on modular assembly of labeled components. Teams building assay reagents use the alkyne handle to connect azide-functional reporters, capture moieties, or signal-amplifying elements through click-compatible coupling steps, enabling rapid interchange of reagent parts without redesigning the entire conjugate. The PEG2 spacing and carboxylate functionality support robust reagent formatting for labeling workflows, helping maintain consistent conjugation chemistry and enabling multistep construction of complex assay formats.