AF 568 Carboxylic Acid is a bright green-fluorescent dye that is structurally identical to Alexa Fluor 568. With its high photostability and pH resistance, it has become one of the most widely used fluorophores in life sciences.

Its hydrophilic nature makes it an ideal choice for labeling sensitive proteins. AF 568 is perfect for a variety of imaging applications, including confocal microscopy, flow cytometry (FACS), and labeling cell cultures and tissues.

The carboxylic acid group can also be utilized for the synthesis of activated esters—such as sulfo-NHS, TFP (2,3,5,6-tetrafluorophenol), and STP (4-sulfo-2,3,5,6-tetrafluorophenol)—or modified with hydrazines, hydroxylamines, or amines in aqueous media using water-soluble carbodiimides. This allows conjugation to molecules containing amino groups, including proteins, antibodies, and peptides. Consequently, AF 488 carboxylic acid is commonly used during solid-phase peptide synthesis to modify peptides in situ in the presence of activating agents like HATU.