Atto 633 belongs to a new generation of fluorescent labels for the red spectral region. The dye is designed for application in the area of life science, e.g. labelling of DNA, RNA or proteins. Characteristic features of the label are strong absorption, high fluorescence quantum yield, high photostability, good water solubility, and very little triplet formation. Atto 633 is a cationic dye. After coupling to a substrate the dye carries a net electrical charge of +1. In common with most Atto-labels, absorption and fluorescence are independent of pH, at least in the range of pH 2 to 11, used in typical applications.Atto-Dye Labeled Phospholipids Sigma-Aldrich offers a variety of glycero-phospholipids carrying one or two fatty acid groups (lipophilic groups) and a phosphate ester residue (hydrophilic group). They are labeled at the hydrophilic head group. After incorporation of the phospholipid into a membrane the fluorophore is located at the water/lipid interface of the membrane. We currently provide 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), palmitoyl-sn-glycero-phosphoethanolamine (PPE), and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine (DMPE) labeled with Atto-dyes.find more information here