N-(Azido-PEG3)-N-Fluorescein-PEG3-acid | CAS 2100306-50-9

N-(Azido-PEG3)-N-Fluorescein-PEG3-acid is a fluorescein-labeled, azide-functionalized PEG conjugate designed for bioorthogonal click chemistry workflows. The reagent combines a reactive azide handle with a flexible PEG spacer and a carboxylic acid functionality, enabling stable attachment to biomolecules and materials via copper-free or copper-mediated azide–alkyne cycloaddition strategies. Its water-soluble, probe-like architecture makes it well suited for labeling applications where traceable fluorescence and modular conjugation are required.

1. Fluorescent Biomolecule Labeling

N-(Azido-PEG3)-N-Fluorescein-PEG3-acid is widely used to generate fluorescently tagged proteins, peptides, and oligonucleotide conjugates for analytical and imaging workflows. The azide functionality provides a convenient reactive handle for downstream conjugation to alkyne-bearing partners, while the fluorescein reporter enables sensitive tracking of labeling patterns in gel-based assays, microscopy, and flow-compatible readouts. The PEG linkers help maintain accessibility of both the fluorophore and the reactive site, supporting consistent staining and reduced steric interference during conjugation.

2. Surface And Material Functionalization

N-(Azido-PEG3)-N-Fluorescein-PEG3-acid supports fluorescent surface modification of polymers, hydrogels, and other biomaterials through azide–alkyne click attachment to alkyne-functionalized substrates. Researchers use this reagent to incorporate a stable, tethered fluorescein signal into material coatings and interfaces, enabling visualization of surface coverage, diffusion, and material-to-material coupling events. The presence of a carboxylic acid group also facilitates formulation and handling in aqueous systems, which is valuable for creating reproducible labeling densities on material platforms.

3. Imaging-Compatible Conjugation Probes

N-(Azido-PEG3)-N-Fluorescein-PEG3-acid is commonly selected for constructing imaging-compatible probes where a fluorophore must remain accessible after conjugation. By providing a modular azide handle, the reagent can be incorporated into multi-component labeling schemes that include targeting ligands, affinity handles, or scaffold molecules bearing complementary alkyne groups. The PEG spacers promote favorable probe mobility and reduce quenching or restricted rotation effects that can accompany more rigid conjugates, supporting robust fluorescence signal for microscopy and instrument-based characterization.

4. Assay Reagents For Click Workflows

N-(Azido-PEG3)-N-Fluorescein-PEG3-acid is frequently used as a fluorescent reporter reagent in click chemistry assay development and reagent screening. Laboratories employ it to monitor successful conjugation, compare labeling efficiencies across different alkyne partners, and validate the completeness of labeling in workflow optimization studies. Its combination of azide reactivity and fluorescein readout makes it practical for quick, high-signal verification steps during assay prototyping, method transfer, and routine quality checks in research settings.