Gold Nanoparticles as a Surface to Immobilize Gadolinium-Hydroxypyridinone (HOPO) Complexes for Use a Magnetic Resonance Imaging (MRI) Contrast Agents

P.J. Klemm, P.J. Straney, M.N. Keyser, J.E. Millstone, K.N. Raymond
UC Berkeley, US

Keywords: magnetic resonance imaging (MRI), contrast agent, lanthanide, gadolinium, gold nanoparticle, bimodal imaging

Summary:

MRI Contrast Agents have the potential for increased relaxivity and lower dosage when they are immobilized on a macromolecular solid support. Gold nanoparticles are an excellent choice due to their facile synthesis, low toxicity, and tailorable surface chemistry which can be used to simultaneously conjugate MRI contrast agents, targeting groups, solubilizing groups, and other multimodal imaging agents. Hexadentate Gd-HOPO complexes have been conjugated with short, rigid linkers to limit local motion of Gd(III) on gold nanoparticles and increase relaxivity. These complexes have q values of 2-3 water molecules coordinated to the inner sphere of Gd(III) for increased water exchange rates. By increasing the molecular weight, water exchange rate and q value, these compounds increase the relaxivity of commercial agents by an order of magnitude and have large per particle relaxivities.