ATTO 647 NHS ester is manufactured by AAT Bioquest for research and development use. ATTO 647 is a rhodamine-derived fluorescent dye optimized for applications within the red spectral region, offering spectral characteristics similar to Cy5. Its characterized by a high molar absorptivity, robust fluorescence quantum yield, high photostability, and good aqueous solubility, making it well-suited for demanding experimental conditions. The dye is highly hydrophilic, with an excitation maximum between the 615-660 nm range, making it compatible with the 633 nm He:Ne laser, 647 nm Krypton-Ion laser, and 650 nm diode laser. As a zwitterionic molecule, ATTO 647 carries a net neutral charge. The dye is stable under physiological pH conditions and in buffers with a pH of up to 8, though it gradually degrades at higher pH levels. ATTO 647 is ideal for advanced applications in single-molecule detection and high-resolution microscopy techniques, including PALM, dSTORM, and STED microscopy. It is also compatible with flow cytometry (FACS), fluorescence in situ hybridization (FISH), FRET, and various other biological assays.

NHS esters react selectively and efficiently with primary amines (such as the side chains of lysine residues or aminosilane-coated surfaces) at pH 7-9, forming stable covalent amide bonds. This property makes ATTO 647 NHS ester an excellent choice for labeling peptides and amine-modified oligonucleotides. For labeling antibodies and other proteins, we highly recommend our iFluor® dyes that are highly water soluble and are optimized for labeling proteins.