Assessment of Bis-macrocyclic Compounds as Calcium-sensitive MR Contrast Agents
Abstract
The ability of non-invasively observing changes in the Ca2+ concentrations is important in the understanding of a great variety of neuronal processes. Several compounds were designed (Fig.1) to take advantage of the different binding abilities of carboxylates and phosphonates to gadolinium. Furthermore the different affinities of the two functional groups to Ca2+ permit to obtain free coordination sites at gadolinium. The generation of these coordination sites, which are mandatory for water relaxivity, depends on the structure of the complexes and the Ca2+ concentration. Gadolinium complexes 1 and 2 were synthesized and relaxivity studies were performed.