sulfo-Cyanine3.5 carboxylic acid

Sulfo-Cyanine3.5 carboxylic acid is a sulfonated cyanine dye designed for aqueous fluorescent labeling workflows where bright red-to-near-infrared emission and water solubility are important. Its carboxylic acid functionality supports conjugation strategies that attach the fluorophore to biomolecules and materials, enabling fluorescence imaging and labeling-based assay development with reduced aggregation in biological buffers.

1. Protein And Peptide Labeling

Sulfo-Cyanine3.5 carboxylic acid is used by chemical biology and proteomics groups to generate fluorescent protein and peptide conjugates for downstream imaging and binding studies. Researchers typically incorporate the dye into labeling workflows where the sulfonated cyanine scaffold maintains solubility in aqueous media while the carboxyl group enables covalent attachment to amine- or hydrazide-bearing partners via established bioconjugation chemistries. The resulting conjugates are commonly employed as fluorescent tags in microscopy experiments, fluorescence-based binding assays, and reagent development for tracking biomolecular interactions.

2. Fluorescence Microscopy Tracing

Sulfo-Cyanine3.5 carboxylic acid supports fluorescence microscopy applications where a cyanine dye with strong emission in the red spectral region is advantageous for cellular or biomaterial imaging. Lab teams use dye-conjugated biomolecules to trace distributions, monitor uptake or binding to experimental surfaces, and visualize labeled components in multi-color imaging sets where spectral separation from common green fluorophores is beneficial. The sulfonate substitution helps maintain dye performance in buffer-containing imaging conditions, supporting consistent staining and washing behavior during fixed-sample workflows and microscopy reagent optimization.

3. Flow Cytometry Fluorescent Labeling

Sulfo-Cyanine3.5 carboxylic acid is applied in flow cytometry workflows that require a water-soluble cyanine fluorophore for labeling biomolecules used in cell-surface or binding assays. Researchers prepare fluorescent conjugates to stain targets in suspension, then quantify fluorescence intensity by FACS to compare labeled populations across experimental conditions. The dye's sulfonated character helps reduce nonspecific dye aggregation in aqueous staining buffers, while the carboxyl functionality enables conjugate construction that can be matched to standard cytometry labeling pipelines for reagent screening and assay development.

4. Fluorescent Bioassay Reagents

Sulfo-Cyanine3.5 carboxylic acid is frequently incorporated into fluorescence-based bioassay reagent development where a cyanine dye serves as a stable reporting label on assay constructs. Assay developers use the dye to build fluorescent readouts for binding or detection formats that rely on covalent labeling of proteins, affinity reagents, or other assay components. In these workflows, the dye's aqueous compatibility and carboxyl handle facilitate consistent conjugate preparation for kit-style assay optimization, plate-based fluorescence measurements, and comparative studies of labeled reagent performance under buffered conditions.