Propargyl-PEG4-O-C1-NHS ester | CAS 1161883-51-7

Propargyl-PEG4-O-C1-NHS ester is a PEG-based, NHS-activated click chemistry reagent that couples a terminal alkyne handle with an N-hydroxysuccinimide ester for efficient conjugation to primary amines. As a bifunctional linker, it is commonly used to introduce a propargyl group for subsequent copper-catalyzed azide–alkyne cycloaddition (CuAAC) labeling, enabling modular assembly of bioconjugates, surface coatings, and imaging reagents. The flexible PEG4 spacer and the NHS ester make it particularly relevant for preparing amine-functional biomolecules and materials that can later be “clicked” to azide-bearing partners under standard bioconjugation workflows.

1. Amine-Functional Biomolecule Labeling

Propargyl-PEG4-O-C1-NHS ester is widely used to functionalize proteins, peptides, and antibody fragments that present accessible primary amines, such as lysine residues or engineered amino tags. The NHS ester enables straightforward pre-installation of a terminal alkyne handle, which can then be used to attach azide-functional probes, affinity handles, or reporters via CuAAC. This approach is commonly adopted in chemical biology workflows where researchers need orthogonal, modular conjugation steps to build multicomponent labeling strategies for mechanistic studies, target engagement assays, and assay development.

2. Surface And Material Functionalization

Propargyl-PEG4-O-C1-NHS ester supports the preparation of alkyne-functional surfaces and biomaterials by reacting with amine-bearing coatings and substrates. After immobilization, the introduced propargyl groups serve as defined attachment points for subsequent azide-bearing ligands, fluorescent dyes, or capture reagents, allowing controlled construction of patterned interfaces and reagent platforms. The PEG4 spacer helps maintain accessibility of the reactive handle on the material surface, which is valuable when downstream click labeling requires efficient coupling to bulky or sterically demanding azide partners.

3. Multivalent Probe And Library Construction

Propargyl-PEG4-O-C1-NHS ester is frequently selected for building multivalent probe designs and reagent libraries that require consistent alkyne installation across multiple scaffolds. By using the NHS ester to conjugate the reagent to a set of amine-containing components, researchers can generate a panel of alkyne-tagged building blocks that later undergo uniform CuAAC coupling to a shared azide library. This workflow is particularly useful in molecular imaging reagent development and diagnostic reagent research, where modular swapping of azide-bearing reporters, polymers, or targeting moieties accelerates iterative optimization of probe architecture.

4. PEG-Linked Linker For Imaging Reagents

Propargyl-PEG4-O-C1-NHS ester is commonly used as a PEG-linked spacer to prepare imaging and detection reagents that benefit from improved solubility and reduced nonspecific interactions. The PEG4 segment provides a hydrophilic distance element between the conjugated biomolecule (installed through the NHS ester) and the eventual clicked-on reporter, which can help preserve accessibility of the detection moiety after assembly. In molecular imaging and analytical chemistry settings, this reagent supports the construction of fluorescent, affinity, or signal-bearing conjugates by installing a click-ready alkyne on the amine-containing precursor prior to coupling with azide-tagged reporters.