Azido-PEG3-phosphonic acid ethyl ester | CAS 1337527-24-8

Azido-PEG3-phosphonic acid ethyl ester is a PEG3-linked azide building block bearing a phosphonate protected as an ethyl ester, designed for bioorthogonal click chemistry workflows. As an azide functional group, it readily participates in copper-free or copper-mediated azide–alkyne cycloaddition strategies to install PEG spacers onto biomolecules, surfaces, and materials. The combination of the flexible PEG tether and the phosphonate handle makes it particularly relevant for constructing functional conjugates used in chemical biology, molecular imaging tool development, and diagnostic reagent platforms where controlled polarity and stable linker presentation are valuable.

1. Biomolecule PEGylation

Azido-PEG3-phosphonic acid ethyl ester is used to introduce a defined PEG spacer onto peptides, proteins, and nucleic-acid-associated constructs via azide–alkyne click conjugation. Researchers commonly incorporate this reagent when they need to modulate solubility, reduce nonspecific interactions, and tune hydrodynamic properties of fluorescent or affinity-tagged biomolecules for downstream assay development. The phosphonate-bearing functionality supports the creation of conjugates that can be further processed into more polar or charge-balanced forms, enabling robust linker presentation in complex experimental matrices.

2. Surface And Material Functionalization

Azido-PEG3-phosphonic acid ethyl ester serves as a practical crosslinkable handle for functionalizing polymer films, nanoparticles, and biosensor surfaces that have been equipped with complementary alkyne groups. In materials chemistry and biomaterials research, the PEG3 segment helps improve surface wettability and reduces steric crowding, while the phosphonate motif offers an additional chemical handle for subsequent surface chemistry steps or coordination-driven material assembly. This reagent is therefore frequently selected for building modular, click-compatible coatings used in research-grade diagnostic and analytical platforms.

3. Molecular Imaging Probe Building

Azido-PEG3-phosphonic acid ethyl ester is widely applied as a linker component in the construction of molecular imaging probes where stable, well-spaced functional groups are required. Teams developing imaging reagents often use the azide handle to click-connect targeting scaffolds or reporter units to a PEG-bearing backbone, aiming to improve probe dispersion and control the spatial arrangement of imaging moieties. The phosphonate-protected group provides a chemically versatile motif during probe assembly, supporting workflows that require careful tuning of overall polarity and conjugate architecture.

4. Diagnostic Reagent Conjugates

Azido-PEG3-phosphonic acid ethyl ester is used to create click-assembled conjugates for diagnostic reagent development, including affinity reagents and assay-compatible labeling constructs. In laboratory and industrial R&D settings, the PEG3 tether helps standardize conjugate behavior across different assay formats by improving accessibility of reactive sites and limiting aggregation. The phosphonate ethyl ester functionality also supports iterative chemical modification strategies during reagent optimization, enabling researchers to generate consistent, reproducible labeling architectures for analytical workflows.