sulfo-Cyanine3-PEG3-biotin

Sulfo-Cyanine3-PEG3-biotin is a water-soluble cyanine dye conjugate bearing a biotin handle, designed for fluorescence labeling workflows where streptavidin or avidin binding is used to position the fluorophore on biomolecules, nanoparticles, and assay surfaces. The Cy3 optical profile supports standard fluorescence microscopy and plate-based detection, while the PEG spacer helps reduce steric effects during biotin-mediated conjugation. This reagent is frequently selected for constructing fluorescent biotinylated probes and for visualizing biotin-dependent binding events in chemical biology and materials research.

1. Streptavidin-Based Biomolecule Labeling

Sulfo-Cyanine3-PEG3-biotin is commonly used to fluorescently tag proteins, peptides, and other biotinylated biomolecules through streptavidin/avidin binding, enabling robust signal generation in binding assays and labeling experiments. Researchers often use it to prepare Cy3-labeled streptavidin conjugates for downstream workflows such as pull-down experiments, binding partner visualization, and fluorescent tracking of biotinylated reagents. The PEG3 linker supports more consistent labeling by spacing the dye from the biotin-binding interface, which can be important when monitoring conjugates by fluorescence microscopy or plate reader.

2. Fluorescence Microscopy And Imaging

Sulfo-Cyanine3-PEG3-biotin is applied in fluorescence microscopy to visualize biotin-dependent localization on surfaces and biomolecular assemblies, including labeled complexes formed with streptavidin-coated substrates. Cell biology and biomaterials groups use the dye to map where biotinylated ligands accumulate, to confirm surface functionalization, and to monitor assembly of biotin-streptavidin networks in imaging experiments. Its sulfonated, water-soluble character supports aqueous staining and washing steps typical of microscopy sample preparation, while the Cy3 emission is compatible with widely used visible-light fluorescence imaging setups.

3. Flow Cytometry Labeling Reagents

Sulfo-Cyanine3-PEG3-biotin is frequently incorporated into flow cytometry labeling strategies for detecting biotin-streptavidin interactions on cells or bead-based systems. Investigators use it to generate Cy3 fluorescence readouts for binding confirmation, reagent coupling verification, and comparative analysis of biotinylated targets across experimental conditions. The PEG spacer and water solubility help support reproducible staining in suspension workflows, where consistent labeling and efficient removal of unbound dye are important for interpretable cytometry signals.

4. Fluorescent Assay Development With Biotin

Sulfo-Cyanine3-PEG3-biotin supports fluorescence-based assay development where biotinylated components are used to organize capture and detection elements, including microplate binding assays and fluorescence readouts for reagent assembly. Assay developers use the reagent as a Cy3 reporter to quantify binding of streptavidin/avidin partners, to validate functionalization of biotin-containing materials, and to support multiplexable fluorescence formats when paired with appropriate optical channels. In these workflows, the biotin handle provides a straightforward route to position the dye at defined binding sites, enabling consistent fluorescence reporting tied to biotin-dependent assembly.