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 9689c5aa-6556-4b3c-b5d1-1e693715ba07's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Far-red/near-IR fluorescent CF®680 dye has excitation/emission at 681/698 nm.