Sulfo-Cyanine5 carboxylic acid | CAS 1144107-82-3

Sulfo-Cyanine5 carboxylic acid is a water-soluble cyanine dye designed for fluorescent labeling workflows where strong far-red emission and aqueous compatibility are required. The carboxylic acid functionality enables conjugation strategies to biomolecules and targeting vectors, supporting fluorescence microscopy, imaging reagent development, and fluorescence-based assay readouts. Its sulfonate-containing structure helps maintain solubility in biological buffers, making it a common fluorophore choice for labeling constructs used in cellular and analytical research.

1. Fluorescent Protein Labeling

Sulfo-Cyanine5 carboxylic acid is used to generate far-red fluorescent conjugates for protein labeling in chemical biology and biomolecular interaction studies. Researchers incorporate the dye into antibody or protein labeling workflows to visualize binding events, track reagent localization, or quantify labeled biomolecules in fluorescence-based assays. The sulfonate-driven water solubility supports conjugate handling in aqueous buffers commonly used for immunoassays, pull-down experiments, and imaging sample preparation.

2. Fluorescence Microscopy Tracing

Sulfo-Cyanine5 carboxylic acid supports fluorescence microscopy experiments that require bright far-red signal with reduced interference from shorter-wavelength autofluorescence. In cell biology and microscopy method development, the dye is frequently incorporated into labeled ligands, macromolecular tracers, or imaging standards to monitor uptake, distribution, or co-localization with other fluorescent channels. Its conjugation-ready carboxyl group enables preparation of microscopy reagents used for widefield and confocal imaging workflows where far-red detection is advantageous.

3. Flow Cytometry Staining

Sulfo-Cyanine5 carboxylic acid is applied in flow cytometry dye conjugate development for labeling cell-associated targets and analyzing fluorescence distributions by instrument-based detection. Lab teams use cyanine5-based conjugates to stain antibodies, binding proteins, or other cell-interacting reagents for population-level readouts in fluorescence analysis. The dye's aqueous character and far-red emission profile make it a practical fluorophore for multicolor cytometry panels where spectral separation from common green and orange channels is needed.

4. Fluorescence Bioassay Development

Sulfo-Cyanine5 carboxylic acid is frequently used to prepare fluorescent reagents for bioassay formats that rely on far-red signal readout, including binding assays and fluorescence quantification of labeled components. Assay developers incorporate the dye into detection conjugates to enable endpoint fluorescence measurements and to support assay workflows where buffer compatibility and consistent aqueous handling are important. The carboxyl functionality supports downstream conjugate construction for assay reagents used in research-grade screening and analytical method development.