Azido-PEG4-hydrazide | CAS 2170240-96-5

Azido-PEG4-hydrazide is a bifunctional PEG-based click chemistry reagent that combines an azide handle for copper-free or copper-mediated azide–alkyne cycloaddition with a hydrazide functionality for hydrazone formation and related conjugation workflows. The short, flexible PEG4 spacer improves aqueous solubility and reduces steric effects when attaching biomolecules, surfaces, or imaging labels. This dual-reactive design is widely used in chemical biology and biomaterials research to build modular conjugates for probe development, surface functionalization, and multistep labeling strategies.

1. Hydrazone Linker Conjugation

Azido-PEG4-hydrazide is commonly used as a coupling reagent for creating hydrazone-linked conjugates in labeling and materials assembly workflows. Researchers employ the hydrazide group to form reversible hydrazone bonds with carbonyl-containing partners, enabling controlled attachment of PEGylated linkers to aldehyde- or ketone-functional biomolecules and scaffold surfaces. The azide functionality allows subsequent click attachment to fluorophores, affinity tags, or polymer components, supporting modular probe generation and multistep construct building in chemical biology labs.

2. Bioorthogonal Imaging Probes

Azido-PEG4-hydrazide is well suited for preparing imaging and detection probes that require both a stable click handle and a PEG spacer to tune solubility and presentation of the reactive group. The azide moiety supports downstream conjugation to alkyne-bearing reporters, including fluorescent dyes and other molecular imaging tags, while the hydrazide enables incorporation into carbonyl-containing targeting motifs or intermediate conjugates. This combination is frequently adopted in molecular imaging reagent development to streamline the synthesis of clickable probe libraries and to improve reproducibility of labeling across different biomolecular formats.

3. Surface And Material Functionalization

Azido-PEG4-hydrazide is used to introduce azide-bearing PEG linkers onto surfaces and biomaterials, enabling subsequent click-based immobilization of biomolecules, nanoparticles, or functional polymers. The hydrazide group provides an additional handle for anchoring to carbonyl-functional substrates or for forming intermediate linkages during surface modification protocols. In biomaterials science, this reagent supports the fabrication of azide-functional coatings and interfaces that can be patterned or selectively decorated using alkyne partners, facilitating the creation of customizable materials for research assays and diagnostic reagent platforms.

4. Multicomponent Assay Reagents

Azido-PEG4-hydrazide is frequently incorporated into multicomponent assay development pipelines where orthogonal or sequential conjugation steps are required to assemble complex reagent systems. The azide group enables efficient click attachment of detection elements such as dye-labeled or affinity-tagged components, while the hydrazide functionality provides a convenient route to connect the PEG linker to carbonyl-bearing intermediates used in reagent assembly. This design supports the construction of modular assay reagents and labeling standards used in research workflows that benefit from flexible interchangeability of clickable components.