Synthesis and characterization of fluorescent cobalamin (CobalaFluor) derivatives for imaging

[GRAPHICS] Fluorescent derivatives of cobalamin have been prepared by linking fluoroph ores to cobalamin through a propylamide spacer. Fluorescein, naphthofluores cein, and Oregon Green derivatives have been prepared in good yield by reac tion of the fluorophore NHS-ester with beta-(3-aminopropyl)cobalamin to for m fluorescent cobalamin conjugates (CobalaFluors) that are potentially suit able for the in vitro and in vivo imaging of transcobalamin receptors on ca ncer cells.