Sulfo-Cy5.5 Picolyl Azide

Sulfo-Cy5.5 Picolyl Azide is a sulfonated, Cy5.5-derived fluorescent azide designed for strain-promoted azide-alkyne click labeling workflows in aqueous environments. Its azide functionality enables robust covalent attachment to alkyne-bearing biomolecules, linkers, and surfaces, while the Cy5.5 fluorophore supports far-red fluorescence readouts commonly used in fluorescence microscopy, imaging, and flow-based assays.

1. Biomolecule Labeling

Sulfo-Cy5.5 Picolyl Azide is used to fluorescently tag proteins, peptides, and affinity reagents that have been functionalized with an alkyne handle for copper-free click conjugation. Researchers employ it to generate fluorescent bioconjugates for tracking binding events, monitoring reagent localization, and building labeled standards for fluorescence-based assays. The sulfonated character helps maintain aqueous compatibility during labeling and downstream purification steps, which is particularly useful when preparing conjugates for imaging experiments.

2. Fluorescence Imaging Probes

Sulfo-Cy5.5 Picolyl Azide serves as a fluorophore-bearing click partner for constructing imaging probes and multicomponent labeling reagents. In microscopy workflows, it is commonly incorporated into probe assemblies where an alkyne-functional targeting moiety is coupled to the Cy5.5 azide to visualize labeled structures with far-red emission. This approach is also used to prepare fluorescent conjugates for whole-mount or thicker-sample imaging setups where reduced background from shorter-wavelength channels is advantageous.

3. Surface And Material Functionalization

Sulfo-Cy5.5 Picolyl Azide is applied for labeling of biomaterial surfaces and engineered materials that present alkyne groups, including polymer coatings, hydrogels, and nanoparticle or scaffold functional layers. Chemical biology and biomaterials groups use the resulting Cy5.5-tagged surfaces to quantify surface coverage, visualize material distribution, and support fluorescence-based characterization of functionalized interfaces. The azide click handle enables modular construction of fluorescent materials without requiring dye incorporation into the bulk synthesis step.

4. Flow Cytometry Labeling

Sulfo-Cy5.5 Picolyl Azide is used to generate far-red fluorescent conjugates for flow cytometry panels, particularly when an alkyne-functional antibody, ligand, or binding reagent is available. Researchers use click labeling to attach the Cy5.5 fluorophore to targeting constructs for cell-surface or binding assays read out by fluorescence detection. This format is valuable for building consistent labeling reagents and for expanding multiplexed staining schemes using a far-red channel compatible with common cytometers.