sulfo-Cyanine3.5 NHS ester

sulfo-Cyanine3.5 NHS ester is a water-soluble, NHS-ester activated cyanine dye designed for efficient amide coupling to primary amines under standard bioconjugation conditions. As a fluorescent labeling reagent, it belongs to the NHS ester class commonly used for conjugating dyes to proteins, peptides, antibodies, and other amine-containing biomolecules. Its sulfonated, hydrophilic cyanine framework supports strong optical imaging workflows and compatibility with aqueous labeling buffers, making it a frequent choice for building fluorescent probes and imaging reagents in chemical biology and molecular imaging research.

1. Protein Fluorescent Labeling

sulfo-Cyanine3.5 NHS ester is widely used to generate fluorescently labeled proteins for microscopy, flow cytometry, and fluorescence-based binding assays. The NHS-ester activation targets accessible lysine residues and N-termini on proteins, enabling robust preparation of conjugates for tracking biomolecular localization, studying macromolecular interactions, and producing labeled standards for assay development. Because the dye is sulfonated and water-soluble, labeling can be performed in aqueous buffers that are compatible with many protein formats, including enzymes, scaffolds, and affinity reagents.

2. Antibody And Ligand Conjugates

sulfo-Cyanine3.5 NHS ester supports the preparation of fluorescent antibodies and targeting ligands used in immunostaining workflows and receptor-binding studies. Researchers commonly apply the dye to antibody fragments and full-length IgG to create imaging reagents for cell-surface visualization, multiplexed labeling strategies, and fluorescence readouts in binding characterization. The NHS-ester chemistry is particularly useful when downstream workflows require a stable covalent dye attachment to maintain signal during washing steps and assay handling.

3. Peptide And Biomolecule Tagging

sulfo-Cyanine3.5 NHS ester is used to fluorescently tag peptides, protein domains, and other amine-bearing biomolecules to support tracking in biochemical assays and imaging experiments. The reagent’s NHS activation enables straightforward covalent attachment to peptide N-termini and lysine side chains, facilitating the generation of fluorescent probes for monitoring uptake, trafficking, or assembly processes in model systems. In molecular imaging tool development, this dye format is also leveraged to create labeled building blocks for constructing multi-component fluorescent constructs.

4. Surface and Material Functionalization

sulfo-Cyanine3.5 NHS ester is commonly applied to label amine-functionalized surfaces and biomaterial platforms, including polymer coatings, hydrogel matrices, and derivatized nanoparticles bearing primary amines. By covalently attaching the cyanine dye to surface amine groups, it becomes possible to create stable fluorescent materials for microscopy-based characterization, spatial mapping of functional layers, and visualization of surface interactions. This application is frequently used in biomaterials science and diagnostics reagent development where durable fluorescence under aqueous handling is required for robust readouts.