Sulfo-Cyanine5.5 carboxylic acid

Sulfo-Cyanine5.5 carboxylic acid is a water-soluble cyanine dye designed for fluorescent labeling workflows where bright, far-red emission and carboxylic acid functionalization are required. Its sulfonated character supports aqueous conjugation and imaging compatibility, and the carboxyl group enables straightforward attachment to amine-containing biomolecules or surfaces via standard coupling strategies used in fluorescence microscopy and labeling studies.

1. Antibody And Protein Labeling

Sulfo-Cyanine5.5 carboxylic acid is used to generate far-red fluorescent conjugates for immunolabeling and protein tracking in research laboratories. Researchers commonly couple the dye to antibodies, antibody fragments, enzymes, or other purified proteins to produce imaging reagents for fluorescence microscopy, fluorescence-based binding experiments, and flow cytometry panels where spectral separation from common green/orange dyes is advantageous. The water-soluble sulfonate functionality helps maintain performance in aqueous buffers during staining and washing steps, supporting robust visualization of labeled targets in fixed-cell imaging and analytical workflows.

2. Fluorescence Microscopy Staining

Sulfo-Cyanine5.5 carboxylic acid supports cellular and biomolecular staining applications that benefit from far-red fluorescence, including multicolor microscopy experiments and localization studies. Typical users include cell biology groups and core microscopy facilities that prepare fluorescent conjugates or labeled probes for imaging of proteins, extracellular binding events, or biomolecule distributions on cells and biomaterial surfaces. The dye's carboxylic acid handle allows it to be incorporated into labeling reagents that are compatible with common staining pipelines, enabling researchers to follow labeled structures with reduced background from autofluorescent cellular components that often dominate shorter wavelengths.

3. Flow Cytometry Fluorescent Labeling

Sulfo-Cyanine5.5 carboxylic acid is applied in flow cytometry workflows that require a far-red channel for gating and multiplexed analysis. Investigators label antibodies, affinity reagents, or other biomolecular binders with the dye to quantify binding to cell-surface targets or to track labeled biomolecules in suspension assays. The dye's aqueous character supports preparation in standard cytometry buffers, while the far-red spectral region helps reduce overlap with frequently used fluorophores in green/orange channels, supporting cleaner multicolor panel design for immunophenotyping and biomolecule binding studies.

4. Fluorescent Tracing In Bioconjugates

Sulfo-Cyanine5.5 carboxylic acid is frequently incorporated into fluorescent bioconjugates used for tracing and localization of biomolecules in material science and chemical biology experiments. Teams developing labeled polymers, surface coatings, or reagent conjugates use the dye to visualize transport, adsorption, or binding of functionalized constructs on substrates and biomaterials. The carboxylic acid functionality enables integration into conjugation schemes that produce stable fluorescent tags for downstream imaging readouts, supporting studies where far-red fluorescence provides improved contrast against background signals in complex sample matrices.