99mTc, 90Y and 177Lu Labelled Iron Oxide Nanoflowers Designed for Potential Use in Dual Magnetic Hyperthermia/Radionuclide Cancer Therapy and Diagnosis.

Development of a complex based on iron-oxide nanoparticles (IONP) for diagnosis and dual magnetic hyperthermia/radionuclide cancer therapy accomplishing high yields of radiolabelling and great magnetic heat induction is still a challenge. We report here the synthesis of citric acid (CA), poly(acrylic acid) (PAA) and polyethylene glycol (PEG) coated IONP and their labelling with three radionuclides, technetium (99mTc), yttrium (90Y) and lutetium (177Lu), aiming potential use in cancer diagnosis and therapy. Polyol synthesized IONP are flower-like structure with 13.5 nm spherically shaped cores and 24.8 nm diameter. PAA-coated nanoparticles (PAA@IONP) showed the best characteristics such as very high radiolabelling yields (>97.5%) with all three radionuclides, and excellent in vitro stabilities with less than 10% of radionuclides detaching after 24 h. Heating ability of PAA@IONP in an alternating external magnetic field showed ILP value of 7.3 nHm2/kg, that is one of higher reported. Additionally, PAA@IONP itself presented no significant cytotoxicity to the CT-26 cancer cells, reaching IC50 at 60 µg/mL. However, under the external magnetic field, they show hyperthermia-mediated cells killing, which correlated with the magnetic field strength and time of exposure. Since PAA@IONP are easy to prepare, biocompatible and with excellent magnetic heat induction, these nanoparticles radiolabelled with high energy beta emitters 90Y and 177Lu have valuable potential as agent for dual magnetic hyperthermia/radionuclide therapy, while radiolabelled with 99mTc could be used in diagnostic imaging.