N-(Azido-PEG2)-N-Fluorescein-PEG3-acid | CAS 2086689-04-3

N-(Azido-PEG2)-N-Fluorescein-PEG3-acid is a fluorescein-based, azide-functionalized PEG conjugate designed for copper-free or copper-mediated click chemistry workflows, enabling efficient attachment to complementary alkyne-bearing partners. The reagent couples a bright, widely used fluorophore with a flexible PEG spacer architecture and a terminal acid handle, which helps tune solubility and downstream conjugation behavior in aqueous labeling and imaging formats. Its azide group makes it a versatile labeling intermediate for biomolecular tagging, probe construction, and material surface functionalization where fluorescent readout is required.

1. Fluorescent Biomolecule Labeling

N-(Azido-PEG2)-N-Fluorescein-PEG3-acid is commonly used to generate fluorescently tagged biomolecules through azide–alkyne click conjugation to alkyne-functional proteins, peptides, carbohydrates, or nucleic-acid scaffolds. Researchers rely on the PEG spacers to reduce steric hindrance and improve labeling uniformity in complex biological buffers, while the fluorescein core provides sensitive optical tracking in microscopy and plate-based assays. The terminal acid functionality also supports practical handling during probe preparation and conjugate purification for downstream studies that require stable, water-compatible fluorescent constructs.

2. Live-Cell Imaging Probes

N-(Azido-PEG2)-N-Fluorescein-PEG3-acid serves as a fluorescent click handle for assembling imaging reagents that target specific cellular components after conjugation to suitable alkyne-bearing targeting ligands or uptake vectors. The azide functionality enables modular probe design, allowing imaging scientists to swap targeting moieties without re-derivatizing the fluorophore each time. The PEGylated fluorescein format is frequently selected for imaging workflows that benefit from improved solubility and reduced nonspecific interactions compared with more rigid or less hydrated dye conjugates.

3. Diagnostic and Assay Reagents

N-(Azido-PEG2)-N-Fluorescein-PEG3-acid is applied in the development of fluorescent assay reagents where click chemistry is used to couple detection components to capture surfaces or reporter scaffolds. In diagnostic reagent development, the azide group supports controlled attachment to alkyne-functional linkers used in microplate formats, bead-based assays, or lateral-flow-style labeling schemes, while fluorescein provides a convenient readout compatible with standard fluorescence instrumentation. The acid-bearing, PEG-separated architecture helps maintain reagent stability and handling characteristics during assay reagent preparation and storage.

4. Surface Functionalization for Materials

N-(Azido-PEG2)-N-Fluorescein-PEG3-acid is used to fluorescently functionalize biomaterials and engineered surfaces via azide–alkyne click coupling to alkyne-presenting coatings, polymer films, or hydrogel components. Materials scientists leverage the PEG spacers to improve dye presentation at the interface and to support homogeneous surface labeling that is suitable for optical monitoring of material architecture and binding events. The conjugate’s acid functionality is also advantageous for formulating surface-modified materials with reproducible dispersion and for integrating fluorescent tags into multi-component material systems used in research and industrial laboratory settings.