N,N'-bis-(propargyl-PEG4)-Cy5 | CAS 2107273-08-3

N,N'-bis-(propargyl-PEG4)-Cy5 is a Cy5-based fluorescent labeling building block bearing two propargyl (alkyne) groups separated by PEG4 spacers, enabling efficient click chemistry conjugation to azide-functional biomolecules, polymers, and surfaces. Its Cy5 chromophore provides far-red fluorescence for imaging workflows where reduced background from shorter-wavelength channels is beneficial, and the PEG spacers help mitigate steric constraints during bioconjugation. Researchers use this reagent to construct fluorescent conjugates for microscopy, flow cytometry, and fluorescence-based assay development, as well as to engineer labeled materials and nanoparticles with defined dye loading.

1. Biomolecule Labeling

N,N'-bis-(propargyl-PEG4)-Cy5 is used to generate far-red fluorescent conjugates for proteins, peptides, and other azide-bearing biomolecules via copper-catalyzed azide-alkyne cycloaddition. Common workflows include labeling targeting ligands, forming fluorescent affinity reagents, and preparing dye-tagged secondary reagents for downstream imaging or quantification. The bis-propargyl design supports multivalent attachment strategies that can improve conjugate robustness in labeling schemes where single-point attachment may be limiting, while the PEG4 spacers help maintain dye accessibility for consistent fluorescence readout.

2. Fluorescence Microscopy

N,N'-bis-(propargyl-PEG4)-Cy5 is frequently incorporated into fluorescent labeling reagents for cellular and molecular imaging experiments using Cy5-compatible excitation/emission filter sets. Researchers employ azide-functional capture systems, such as azide-modified antibodies or azide-tagged biomolecule assemblies, to visualize binding and localization in fluorescence microscopy. The PEG-linked dye format is also used to create conjugates for multicolor staining panels, where far-red emission helps reduce spectral overlap with common green/orange channels and supports clearer separation of targets in overlay images.

3. Flow Cytometry Staining

N,N'-bis-(propargyl-PEG4)-Cy5 supports fluorescence labeling for flow cytometry experiments that require Cy5-range detection, including staining of azide-functional antibodies, affinity probes, and labeled biomolecule complexes. In typical assay development workflows, the reagent is clicked onto azide-tagged reagents to produce stable fluorescent conjugates for cell-surface or extracellular binding studies, followed by instrument readout in far-red channels. The PEG4 spacing and dual alkyne functionality help accommodate conjugation to larger biomolecular formats while maintaining dye presentation for reliable signal collection.

4. Click-Functional Materials

N,N'-bis-(propargyl-PEG4)-Cy5 is used to fluorescently functionalize polymers, hydrogels, and other biomaterials that incorporate azide groups, enabling spatially defined or batch labeling of material surfaces. Researchers apply this approach to prepare fluorescently tagged scaffolds for biomaterials characterization, to track material interactions in fluorescence imaging experiments, and to create labeled polymer conjugates for assay platforms. The bis-alkyne/PEG architecture supports higher labeling density control compared with mono-functional dye formats, which can be advantageous when engineering fluorescent materials for microscopy readouts or fluorescence-based material assays.