N-(Azido-PEG2)-N-Fluorescein-PEG4-acid | CAS 2086689-06-5

N-(Azido-PEG2)-N-Fluorescein-PEG4-acid is a fluorescent, azide-functionalized PEG conjugate designed for bioorthogonal click chemistry workflows. The reagent combines an azide handle for strain-promoted or copper-catalyzed azide–alkyne cycloaddition compatibility with a fluorescein reporting group for optical tracking. Its PEG spacers and terminal acid functionality make it well-suited for aqueous labeling, imaging, and incorporation into larger biomolecular or materials systems where solubility and conjugation flexibility are important.

1. Fluorescent Biomolecule Labeling

N-(Azido-PEG2)-N-Fluorescein-PEG4-acid is used as a direct fluorescence tag for biomolecules and biomolecular assemblies that require azide-based click conjugation. Researchers commonly incorporate the reagent into labeling strategies for proteins, nucleic acids, and peptide constructs where the PEG linkers help reduce nonspecific interactions and improve performance in aqueous buffers. The fluorescein moiety enables sensitive readout in fluorescence microscopy, gel-based visualization, and plate-based detection formats, while the azide group supports downstream attachment to complementary alkyne-bearing partners used in target-specific probes and multicomponent labeling schemes.

2. Cell Imaging Probe Construction

N-(Azido-PEG2)-N-Fluorescein-PEG4-acid is widely adopted in chemical biology for building imaging probes that combine a clickable fluorophore with modular targeting elements. The azide functionality allows probe assembly by click conjugation to alkyne-functional ligands, affinity reagents, or surface-bound targeting scaffolds, enabling rapid generation of probe variants for microscopy studies. The PEG4-acid architecture supports aqueous handling and helps maintain fluorophore accessibility for optical readout, which is valuable when constructing conjugates for tracking biomolecular localization, trafficking pathways, or dynamic labeling experiments in research settings.

3. Surface and Hydrogel Functionalization

N-(Azido-PEG2)-N-Fluorescein-PEG4-acid is used to introduce fluorescent reporting capability onto azide-compatible surfaces and soft materials that are subsequently patterned or functionalized via click chemistry. Materials scientists incorporate the reagent into polymer networks, hydrogels, and coating layers where PEG spacing improves dispersion and reduces steric hindrance during conjugation to alkyne-bearing crosslinkers or capture ligands. The terminal acid group can also support formulation and surface chemistry considerations, while fluorescein provides a convenient handle for monitoring uniformity, diffusion behavior of labeled components, and spatial patterning of functional sites.

4. Diagnostic Reagent and Assay Development

N-(Azido-PEG2)-N-Fluorescein-PEG4-acid supports the development of fluorescence-based diagnostic reagents and assay components that rely on modular click conjugation. Assay developers use the reagent to generate labeled detection constructs by coupling the azide-bearing fluorescein conjugate to alkyne-functional affinity reagents, polymers, or scaffold molecules used to build multiplexed readouts. Its PEG-mediated solubility and the optical properties of fluorescein make it a practical building block for assay workflows requiring consistent labeling, straightforward optical quantification, and flexible assembly of reagent sets for research and industrial assay prototyping.