Propargyl-PEG1-SS-PEG1-acid | CAS 1807503-85-0

Propargyl-PEG1-SS-PEG1-acid is a PEG-based, cleavable click chemistry linker that incorporates a terminal propargyl group for copper-catalyzed azide–alkyne cycloaddition (CuAAC) and a central disulfide (SS) for redox-responsive linkage. The molecule is designed as a bifunctional PEG spacer bearing a terminal carboxylic acid, enabling straightforward conjugation to amine-bearing biomolecules or surfaces while providing a reactive handle for subsequent click coupling. Such structural features make it well suited for building modular, exchangeable bioconjugates, including redox-responsive probe and material platforms where controlled assembly and disassembly are valuable.

1. Redox-Responsive Bioconjugates

Propargyl-PEG1-SS-PEG1-acid is commonly used to generate redox-responsive bioconjugates by combining a click-reactive propargyl handle with a disulfide-containing tether that can be incorporated into larger molecular constructs. Researchers use the terminal carboxylic acid for coupling workflows to attach the linker to amine-functional biomolecules, peptides, or carrier scaffolds, and then rely on CuAAC to install azide-bearing partners such as targeting ligands, fluorophores, affinity tags, or affinity reagents. The PEG spacers help maintain solubility and reduce steric constraints during multistep assembly, which is particularly useful when building complex conjugates for analytical chemistry and chemical biology tool development.

2. Förster-Free Imaging Probes

Propargyl-PEG1-SS-PEG1-acid supports the preparation of imaging and detection probes where modular labeling is required without committing to a single dye or targeting chemistry at the outset. In molecular imaging and diagnostic reagent development workflows, the linker’s propargyl group enables rapid CuAAC attachment of azide-functional reporters, including fluorescent dyes, quencher pairs, or other signal-generating tags used in assay development and instrument-based readouts. The disulfide linkage provides an additional design element for constructing probes that can undergo structural changes under reducing conditions present in many experimental environments, which can be advantageous for tuning probe behavior during sample processing and signal generation. The carboxylic acid functionality further facilitates attachment to probe backbones or surface coatings used in assay formats.

3. Surface Functionalization For Assays

Propargyl-PEG1-SS-PEG1-acid is widely applied in surface chemistry to create clickable, redox-responsive functional layers for assay development and analytical platforms. The terminal carboxylic acid enables coupling to amine-present surfaces and coatings, while the propargyl group allows subsequent CuAAC immobilization of azide-tagged capture reagents, such as oligonucleotide probes, affinity ligands, or labeled reporter molecules. PEG spacing improves accessibility of immobilized components and helps reduce nonspecific interactions, which is beneficial for consistent assay performance across varied sample matrices. The central disulfide motif provides a useful handle for designing linkers that can be cleaved or reorganized under controlled reducing conditions during regeneration, workflow optimization, or post-assay processing.

4. Modular PEG-Based Materials

Propargyl-PEG1-SS-PEG1-acid is used as a building block for constructing PEG-containing, redox-responsive materials where click-based modularity is required. Biomaterials and chemical biology groups incorporate this linker to introduce clickable sites into polymer networks, hydrogel components, or scaffold surfaces, then use CuAAC to attach functional moieties such as bioactive peptides, affinity handles, or imaging tags. The PEG1 spacers support water compatibility and help tune the local microenvironment around the attached functionalities, while the disulfide linkage offers a design route to materials that can undergo controlled cleavage or rearrangement in reducing conditions encountered during in vitro workflows. The carboxylic acid functionality supports integration into larger material architectures via standard coupling strategies to amine-bearing components.