Unlike other reactive fluoresceins, 6-DTAF not only reacts with amino groups, but also reacts with thiol groups and even directly reacts with hydroxy groups such as polysaccharides and other alcohols in aqueous solution at pH above 9. The 6-isomer is more preferably used for labeling oligonucleotides and nucleic acids.
Prigent-Richard S, et al. (1998). Fluorescent and radiolabeling of polysaccharides: binding and internalization experiments on vascular cells. J Biomed Mater Res 40, 275-81; Blakeslee D (1977). Immunofluorescence using dichlorotriazinylaminofluorescein (DTAF). II. Preparation, purity and stability of the compound. J Immunol Methods 17, 361-4.