Preliminary Evaluation of Iron Oxide Nanoparticles Radiolabeled with 68 Ga and 177 Lu as Potential Theranostic Agents.

Theranostic radioisotope pairs such as Gallium-68 ( 68 Ga) for Positron Emission Tomography (PET) and Lutetium-177 ( 177 Lu) for radioisotopic therapy, in conjunction with nanoparticles (NPs), are an emerging field in the treatment of cancer. The present work aims to demonstrate the ability of condensed colloidal nanocrystal clusters (co-CNCs) comprised of iron oxide nanoparticles, coated with alginic acid (MA) and stabilized by a layer of polyethylene glycol (MAPEG) to be directly radiolabeled with 68 Ga and its therapeutic analog 177 Lu. 68 Ga/ 177 Lu- MA and MAPEG were investigated for their in vitro stability. The biocompatibility of the non-radiolabeled nanoparticles, as well as the cytotoxicity of MA, MAPEG, and [ 177 Lu]Lu-MAPEG were assessed on 4T1 cells. Finally, the ex vivo biodistribution of the 68 Ga-labeled NPs as well as [ 177 Lu]Lu-MAPEG was investigated in normal mice. Radiolabeling with both radioisotopes took place via a simple and direct labelling method without further purification. Hemocompatibility was verified for both NPs, while MTT studies demonstrated the non-cytotoxic profile of the nanocarriers and the dose-dependent toxicity for [ 177 Lu]Lu-MAPEG. The radiolabeled nanoparticles mainly accumulated in RES organs. Based on our preliminary results, we conclude that MAPEG could be further investigated as a theranostic agent for PET diagnosis and therapy of cancer.