Alkyne-PEG4-maleimide | CAS 1609651-90-2

Alkyne-PEG4-maleimide is a heterobifunctional click chemistry reagent that combines a terminal alkyne handle for copper-catalyzed azide–alkyne cycloaddition (CuAAC) with a maleimide group for rapid thiol conjugation. The PEG4 spacer provides aqueous compatibility and helps reduce steric effects during biomolecule labeling, while the maleimide enables efficient coupling to cysteine-containing targets such as proteins, peptides, and thiolated biomaterials. This reagent is commonly used to build modular, site-selective conjugates that can be further functionalized with azide-bearing probes, surfaces, or imaging/assay components.

1. Thiol-Selective Protein Labeling

Alkyne-PEG4-maleimide is widely used to introduce a clickable alkyne functionality onto cysteine-bearing proteins and peptides via maleimide–thiol coupling. Researchers employ it to create protein conjugates that retain native-like solubility due to the PEG spacer, enabling subsequent CuAAC attachment of fluorophores, affinity tags, or other azide-functional components. In workflow terms, it supports modular labeling strategies where the initial thiol conjugation installs the handle, and downstream click chemistry determines the final probe identity.

2. Surface And Material Functionalization

Alkyne-PEG4-maleimide is used to functionalize thiol-reactive surfaces and biomaterials that present accessible sulfhydryl groups, including thiolated polymers, hydrogel matrices, and engineered material coatings. The reagent enables installation of a terminal alkyne moiety at controlled locations, which can then be used for azide-driven patterning, immobilization, or multicomponent assembly through CuAAC. This approach is particularly valuable for creating stable, covalently linked interfaces for biosensing formats, research-grade material platforms, and modular scaffold architectures.

3. Multicolor Probe And Assay Building

Alkyne-PEG4-maleimide supports the creation of multicomponent chemical probes by first attaching the reagent to a targeting scaffold through maleimide chemistry, followed by CuAAC coupling to azide-tagged reporters. Common downstream uses include generating fluorescent conjugates for microscopy and flow-based assays, constructing ratiometric or multiplexed labeling sets, and preparing standardized probe libraries for method development. The PEG4 linker helps maintain probe accessibility, which is often important when the clickable handle must remain available for efficient coupling to azide partners.

4. Bioconjugation For Nanoconstruct Assembly

Alkyne-PEG4-maleimide is frequently used in nanoconstruct and macromolecular assembly pipelines where thiol-containing biomolecules or nanoparticle surfaces must be endowed with a clickable alkyne for orthogonal growth. After maleimide-mediated attachment to thiolated ligands or surface coatings, the resulting alkyne-bearing constructs can be joined to azide-functional components such as targeting motifs, imaging tags, or secondary structural elements. This design supports stepwise assembly strategies that separate the initial conjugation event from the final “click” incorporation, improving flexibility in constructing complex research tools.