Sulfo-Cyanine5.5 amine | CAS 2183440-45-9

Sulfo-Cyanine5.5 amine is a sulfonated cyanine dye featuring an amine-reactive handle for fluorescent labeling workflows, enabling water-compatible conjugation with biomolecules and polymers. Its far-red emission supports low-background imaging and fluorescence readouts in microscopy and fluorescence-based assays, where stable labeling of proteins, peptides, and nucleic-acid-containing constructs is required. In practice, the sulfonate functionality helps maintain aqueous solubility and reduces nonspecific hydrophobic interactions during labeling and subsequent handling.

1. Protein Conjugation Labeling

Sulfo-Cyanine5.5 amine is commonly used by protein chemistry and chemical biology groups to generate far-red fluorescent protein conjugates for imaging and quantitative fluorescence assays. Researchers typically incorporate the dye into antibodies, antibody fragments, enzymes, and affinity reagents to visualize binding events, track biomolecule localization, or monitor reaction progress in fluorescence readouts. The sulfonated dye scaffold supports aqueous labeling conditions and helps maintain labeling performance during buffer exchanges and downstream assay steps, making it practical for workflows that require reproducible dye loading and consistent fluorescence intensity.

2. Fluorescence Microscopy Tracing

Sulfo-Cyanine5.5 amine supports cellular and subcellular fluorescence microscopy applications where far-red excitation/emission improves contrast against cellular autofluorescence. Imaging teams use dye-labeled proteins, peptides, and polymer carriers to trace biomolecule uptake, trafficking, and surface association in fixed-cell and imaging-compatible preparations. The amine-reactive dye format is also used to prepare fluorescent standards and labeled controls that align with common far-red filter sets, enabling consistent visualization across experiments such as co-localization studies and multi-channel imaging panels.

3. Flow Cytometry Staining

Sulfo-Cyanine5.5 amine is frequently selected for flow cytometry staining strategies that rely on far-red fluorescence to reduce spectral overlap with common fluorophores. Flow cytometry users generate dye-labeled antibodies or labeling reagents to quantify binding to cell-surface targets or to track labeled biomolecules in cell-associated assays. The sulfonated cyanine structure helps support aqueous labeling and washing steps typical of cytometry workflows, supporting robust signal retention during sample processing and instrument acquisition.

4. Nucleic Acid Conjugate Preparation

Sulfo-Cyanine5.5 amine is used in nucleic-acid analysis workflows to produce fluorescently labeled oligonucleotide conjugates for imaging and fluorescence-based nucleic-acid assays. Researchers incorporate the dye into nucleic-acid-containing constructs through amine-directed labeling of modified biomolecules or nucleic-acid-associated carriers, enabling visualization of hybridization-related workflows and fluorescent tracking of nucleic-acid assemblies. Far-red emission from the cyanine scaffold is particularly useful when nucleic-acid assays are performed alongside other fluorescent channels or when background from biological matrices needs to be minimized.