CF® dye labeled dextrans could be used as a fluorescent fluid-phase markers to study cell permeability, endocytosis, or mechanisms of biomolecular delivery. The dextran conjugates are available in a variety of molecular weights, and contain a formaldehyde-fixable free-amine group. CF® dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. UV-excitable blue fluorescent CF®350 dye has excitation/emission at 347/448 nm.