Sulfo-Cyanine3 NHS ester

Sulfo-Cyanine3 NHS ester is a sulfonated cyanine dye activated as an N-hydroxysuccinimide ester for efficient fluorescent labeling of primary amines on proteins, peptides, and antibody conjugates. Its water-soluble, anionic sulfonate design supports aqueous bioconjugation workflows, while the cyanine dye provides bright red/orange fluorescence for microscopy and fluorescence-based assays.

1. Protein And Antibody Labeling

Sulfo-Cyanine3 NHS ester is widely used to generate fluorescently labeled proteins and antibody conjugates for binding studies, immunoassays, and fluorescence imaging workflows. Researchers typically label lysine-containing biomolecules under standard NHS-ester bioconjugation conditions to produce stable amide linkages, enabling direct visualization of target-binding events on membranes, in fixed samples, or in labeled reagent formats. The sulfonated dye structure helps maintain aqueous compatibility during conjugate preparation and downstream handling, which is especially useful when preparing conjugates for fluorescence microscopy or plate-based readouts.

2. Fluorescence Microscopy Staining

Sulfo-Cyanine3 NHS ester supports fluorescent staining of biomolecular targets in microscopy experiments where red/orange emission is advantageous for multicolor panels or for separating signal from common background fluorophores. Common use cases include labeling extracellular proteins, cell-surface or secreted components in fixed-cell workflows, and preparing fluorescent secondary reagents or tracer conjugates for imaging. Because the reagent reacts with accessible primary amines, it is frequently incorporated into staining protocols for immunostaining reagents and fluorescent biomolecule tracers used in confocal and widefield microscopy.

3. Flow Cytometry Conjugates

Sulfo-Cyanine3 NHS ester is used to construct flow cytometry dyes for labeling antibody reagents and other amine-bearing targeting molecules used in cell analysis. In research settings, conjugates prepared from this NHS ester are employed to quantify binding to cell-associated targets by fluorescence readout in the red/orange channel, facilitating experiments such as receptor binding characterization, reagent titration, and assay development for labeled binding reagents. The dye's sulfonated, water-soluble character helps support consistent conjugate handling when preparing staining mixes for instrument-based fluorescence measurements.

4. Fluorescent Bioassay Reagent Development

Sulfo-Cyanine3 NHS ester is frequently incorporated into the development of fluorescence-based bioassay reagents where amine-reactive labeling is needed to create fluorescent reporters. Researchers use the dye to generate labeled assay components such as fluorescent standards, labeled detection reagents, and conjugate controls for plate readers and imaging-compatible assay formats. The NHS-ester functionality enables straightforward preparation of fluorescent conjugates from amine-containing biomolecules, supporting assay workflows that rely on robust, aqueous fluorescence measurements.