Novel carbon nanohybrids as highly efficient magnetic resonance imaging contrast agents

Abstract

Novel carbon nanohybrids based on unmodified metallofullerenes have been successfully fabricated for use as a new magnetic resonance imaging (MRI) contrast agent. The nanohybrids showed higher R 1 relaxivity and better brightening effect than Gd@C82(OH) X , in T 1-weighted MR images in vivo. This is a result of the proton relaxivity from the original gadofullerenes, which retained a perfect carbon cage structure and so might completely avoid the release of Gd3+ ions. A “secondary spin-electron transfer” relaxation mechanism was proposed to explain how the encaged Gd3+ ions of carbon nanohybrids interact with the surrounding water molecules. This approach opens new opportunities for developing highly efficient and low toxicity MRI contrast agents.