IR 680LT (IRDye® 680LT equivalent) is a bright, water-soluble dye that is structurally very similar to the commonly used Cy®5.5 Dye. The water solubility, brightness, and self-quenching characteristics of this dye were significantly improved by the introduction of two additional sulfo groups. Far-red fluorescent IR 680 conjugates are spectrally similar to other 680 nm dyes that are used for flow cytometry, microscopy and other applications. Proteins can be labeled with IR 680 at high molar ratios without significant self - quenching, leading to brighter conjugates and more sensitive detection.
The NHS ester (succinimidyl ester) is the most popular tool for conjugating this dye to a protein or antibody. NHS esters can be used to label to the primary amines of proteins (Lys), amine-modified oligonucleotides, and other amine-containing molecules.