AF 647 NHS ester | CAS 1620475-28-6

AF 647 NHS ester is a reactive Alexa Fluor 647 dye derivative designed for efficient covalent labeling of primary amine-containing biomolecules. As an NHS ester, it is commonly used to prepare fluorescent conjugates for imaging and quantitative fluorescence workflows, leveraging the far-red emission of Alexa Fluor 647 to reduce interference from autofluorescence. Researchers use it to generate stable dye-tagged proteins, peptides, and other amine-rich targets for microscopy, flow cytometry, and fluorescence-based assay development.

1. Protein Antibody Labeling

AF 647 NHS ester is widely used to fluorescently label antibodies, antibody fragments, and other amine-rich proteins for immunofluorescence and binding studies. In typical workflows, the NHS ester reacts with lysine residues and N-termini to produce dye-protein conjugates that can be used to visualize target binding on cells, tissue sections, or immobilized biomolecular surfaces. Far-red Alexa Fluor 647 emission is particularly valued when background from cellular autofluorescence is a concern, supporting robust imaging contrast in multicolor staining panels.

2. Flow Cytometry Staining

AF 647 NHS ester enables preparation of far-red flow cytometry dyes by conjugating the dye to antibodies or other amine-containing labeling reagents used for cell-surface or intracellular marker detection. Flow cytometry users rely on the covalent attachment to maintain consistent staining intensity across samples and to support quantitative comparison between experimental conditions. The far-red spectral region also helps reduce spectral overlap with common fluorophores, supporting cleaner compensation in multiplex cytometry panels.

3. Microscopy Fluorescent Conjugates

AF 647 NHS ester is frequently employed to generate fluorescent labeling reagents for fluorescence microscopy, including labeled proteins used as probes for cellular structures, extracellular targets, or biomolecular interactions. By producing stable amine-reactive dye conjugates, it supports consistent staining and wash-resistant signal for fixed-cell imaging workflows and for labeling of biomolecules on substrates. Researchers also use AF 647-conjugated reagents to build multicolor imaging experiments where far-red emission provides separation from green and orange channels.

4. Biomaterial Surface Functionalization

AF 647 NHS ester is used in biomaterials research to fluorescently tag amine-functionalized polymers, hydrogels, and surface coatings for visualization of material distribution, coating uniformity, and biomolecule adsorption. In these applications, covalent dye attachment allows tracking of functionalized materials during incubation and washing steps, supporting microscopy-based readouts of surface coverage and surface-associated binding events. Far-red fluorescence from Alexa Fluor 647 is often selected to improve contrast against polymer autofluorescence and to facilitate imaging alongside other labels.