MB™ 680R is a bright and photostable far-red dye that emits fluorescence at about 685 nm in the borderline spectral region between far-red and near-IR. Although the absorption maximum is at around 680 nm, this dye can be sufficiently excited by the 633 or 635 nm laser. MB™ 680R dye is water soluble and pH-insensitive from pH 4 to pH 10. MB 680R is a rhodamine-based dye, and like rhodamine dyes in general, it is exceptionally photostable. The superior photostability and excellent brightness of MB 680R make the dye an ideal choice for confocal microscopy and other demanding applications.
TFP (tetrafluorophenyl) ester is an amine-reactive activated ester that reacts with primary amines of biomolecules in the same way as the succinimidyl ester (SE or NHS-ester) to form a stable amide bond. The major advantage of TFP esters over the succinimidyl ester is better resistance to spontaneous hydrolysis during conjugation reactions, which results in more efficient and reproducible labeling of biopolymers. TFP esters are stable for several hours at the basic pH typically used for reactions–far outlasting succinimidyl esters.