Joern Engelmann1, Joerg Henig2, Sven Gottschalk1, Hermann A. Mayer2
1High Field MR Center, Max Planck
Institute for Biological Cybernetics,
Silsesquioxane-based macromolecular MRI-contrast agents have recently been reported to have a compact globular structure resulting in significantly higher relaxivities when compared to smaller MRI-probes. The stability of the core under physiological conditions is unknown so far. We therefore studied the stability of Gadoxane, a new silsesquioxane-based contrast agent connected to eight DOTAGA-gadolinium chelates. The silsesquioxane core was almost completely hydrolyzed under physiological conditions while the integrity of the gadolinium chelate was maintained. In conclusion, these probes cannot be considered as stable anymore. However, their degradability might improve their in vivo-applicability due to a faster renal excretion of the smaller fragments.