Cyanine3B NHS ester | CAS 228272-52-4

Cyanine3B NHS ester is a reactive cyanine dye provided as an N-hydroxysuccinimide (NHS) ester for efficient covalent fluorescent labeling of primary amines on proteins, peptides, and other biomolecules. With excitation and emission in the visible red/orange region, it is widely used as a bright, trackable fluorophore for fluorescence microscopy and fluorescence-based assays where robust conjugate formation is required.

1. Protein And Antibody Labeling

Cyanine3B NHS ester is commonly used to generate fluorescently labeled proteins and antibody conjugates for downstream fluorescence imaging and binding studies. Researchers typically label lysine-containing biomolecules to produce dye-tagged reagents for immunostaining workflows, antigen-binding assays, and visualization of biomolecule distribution in complex samples. The NHS ester functionality enables straightforward conjugation to amine-bearing targets, which supports consistent preparation of labeling reagents for microscopy platforms and plate-based fluorescence measurements.

2. Fluorescence Microscopy Staining

Cyanine3B NHS ester is frequently incorporated into microscopy staining workflows to visualize labeled biomolecules in fixed-cell or fixed-tissue imaging experiments. By covalently attaching the dye to amine-rich targets such as extracellular matrix proteins, cell-surface binding reagents, or antibody conjugates, users obtain red/orange fluorescence suitable for widefield and confocal imaging. The dye's spectral position also makes it a practical component in multi-color imaging panels when paired with compatible fluorophores and filter sets.

3. Flow Cytometry Conjugates

Cyanine3B NHS ester is used to prepare fluorescent conjugates for flow cytometry readouts, particularly when researchers need a stable, covalent dye attachment to amine-containing labeling reagents. Dye-labeled antibodies, protein ligands, or other primary-amine-bearing reagents are generated to quantify binding to cell-associated targets and to track labeled populations by fluorescence intensity. This labeling format supports assay development where reproducible conjugate preparation and consistent fluorescence reporting are important for instrument-based analysis.

4. Fluorescent Bioassay Tracers

Cyanine3B NHS ester is also applied in fluorescence bioassay development as a tracer dye for monitoring biomolecular interactions and reagent localization in solution or on assay surfaces. Conjugates prepared from amine-reactive labeling are used in binding assays, wash-based fluorescence workflows, and imaging-compatible assay formats where a visible-range fluorescent reporter is advantageous. The covalent labeling approach helps reduce dye loss during incubation and washing steps, supporting reliable signal generation in assay development and screening studies.