Cyanine5 NHS ester | CAS 350686-88-3

Name: Cyanine5 NHS ester
Brand: BOC Sciences
Rating: 5 (1 reviews)

Catalog Number	R01-0019
Category	NHS Esters
Molecular Formula	C36H42N3O4
Molecular Weight	580.75

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Product Introduction

During the last years, Cyanine5 (an analog of Cy5®) has become an incredibly popular label in life science research and diagnostics. The fluorophore has its emission maximum in the red region, where many CCD detectors exhibit maximum sensitivity, and biological objects show low background. The dye color is very intense, therefore quantities as small as 1 nmol can be detected in gel electrophoresis by naked eye. This Cyanine5 NHS ester (analog to Cy5® NHS ester) is a reactive dye for the labeling of amino-groups in peptides, proteins, and oligonucleotides. This dye requires a small amount of organic co-solvent (such as DMF or DMSO) to be used in labeling reactions (please see our recommended protocol for more details). This reagent is ideal for very cost-efficient labeling of soluble proteins as well as all kinds of peptides and oligonucleotides. This reagent also works well in organic solvents for small molecule labeling. For more sophisticated targets such as easily degradable proteins, when the use of DMF or DMSO is undesirable, consider using water-soluble sulfo-Cyanine 5 NHS ester which does not require any co-solvent, and features very similar fluorescent properties.

Chemical Information
Product Specification
Application

Chemical Information

Related CAS	1263093-76-0 (tetrafluoroborate)
Purity	NMR 1H, HPLC-MS (95%)
Solubility	very poorly soluble in water (0.19 mM = 127 mg/L), good in polar (DMSO, DMF) and chlorinated (DCM, chloroform) organic solvents
Appearance	dark blue solid

Product Specification

ε, L⋅mol-1⋅cm-1	250000
Fluorescence Quantum Yield	0.2
Excitation	646
Emission	662
Storage	12 months after receival at -20°C in the dark. Transportation: at room temperature for up to 3 weeks. Avoid prolonged exposure to light. Desiccate.

Application

Cyanine5 NHS ester is a reactive cyanine dye designed for stable amine labeling via N-hydroxysuccinimide (NHS) ester chemistry. The bright far-red fluorescence of the Cy5 scaffold makes it a widely used reagent for fluorescence imaging and labeling workflows where low background and convenient conjugation to primary amines are required. Because the NHS ester reacts efficiently with lysine residues and other accessible amino groups, it is commonly incorporated into antibody, protein, peptide, and polymer conjugate preparation for microscopy and fluorescence-based assays.

1. Protein And Antibody Labeling

Cyanine5 NHS ester is frequently used by protein and antibody engineering groups to generate fluorescently labeled binders for fluorescence microscopy, flow cytometry, and binding assays. Researchers typically conjugate the NHS ester to lysine-containing proteins to produce Cy5-tagged antibodies, secondary antibodies, or affinity reagents for visualization of target binding on cells, beads, or immobilized surfaces. The far-red emission is particularly useful when multiplexing with green fluorophores or when reducing interference from autofluorescence in biological samples.

2. Fluorescence Microscopy Tracing

Cyanine5 NHS ester supports fluorescent labeling of biomolecules used as tracers in cellular imaging and materials microscopy. Lab teams often prepare Cy5-conjugated proteins, peptides, or polymer components to visualize uptake, localization, or distribution in fixed-cell studies and biomaterial contexts where far-red detection improves background rejection. The NHS ester format enables straightforward post-labeling of amine-bearing components, allowing researchers to tailor labeling density for imaging reagents used in confocal and fluorescence microscopy workflows.

3. Flow Cytometry Staining Reagents

Cyanine5 NHS ester is commonly used to prepare Cy5-labeled staining reagents for flow cytometry and bead-based fluorescence readouts. Immunology and cell biology laboratories frequently conjugate the dye to antibodies or other amine-containing binders to generate far-red flow-compatible probes for target expression analysis, phenotyping panels, and control reagents. The reactive NHS ester chemistry helps streamline preparation of fluorescent conjugates from standard protein inputs, supporting consistent labeling for instrument-based quantification.

4. Fluorescence Bioassay Conjugates

Cyanine5 NHS ester is also applied in fluorescence assay development where far-red reporters are required for monitoring binding, immobilization, or assay signal generation. Researchers use Cy5-labeled proteins, peptides, or polymers as fluorescent tags in plate-based assays, microarray formats, and imaging-compatible biosensor prototypes. The dye's NHS reactivity is particularly valuable when building custom fluorescent conjugates from amine-functional biomolecules to integrate into assay platforms that rely on Cy5 readout.