AZDye 660 Acid (FP-1820)

AZDye 660 is a bright and photostable near-IR dye that is spectrally almost identical to Alexa Fluor® 660 and CF660® 680RD. AZDye 680 is often used for a bright and photostable far-red dye with excitation ideally suited to the 633 or 647 nm laser line. AZDye 660 ideally suited for the 633 nm laser line. This near-IR fluorescent dye is water soluble and pH-insensitive from pH 4 to pH 10. AZDye 660 molecules can be attached to proteins at high molar ratios without significant self-quenching, leading to brighter conjugates and more sensitive detection. The long wavelength emission allows for detection in complex samples with auto-fluorescent background signals.

The carboxylic acid of AZDye 660 is a reagent of choice for the preparation of custom activated esters that often are not commercially available. Examples of such activated esters include sulfo-NHS, TFP (2,3,5,6-Tetrafluorophenol), STP (4-Sulfo-2,3,5,6-Tetrafluorophenol, Sodium Salt). Another common application for non-activated carboxylic acid is peptide modification during solid phase synthesis, which usually requires in-situ activation with peptide coupling regents, for example HATU.