Study of magnetic ferrite nanoparticles labeled with 99mTc-pertechnetate

This study examined the applications of novel non-polymer magnetic ferrite nanoparticles (Fe3O4 NPs) labeled with Tc-99m-pertechnetate ((TcO4)-Tc-99m (-)). The radiochemistry, chemistry, and biodistribution of Fe3O4 NPs labeled with (TcO4)-Tc-9m (-) were analyzed. This paper employed instant thin layer chromatography and magnetic adsorption to evaluate the labeling efficiency and stability of Tc-99m-Fe3O4 at various reaction conditions. A scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectrometer, laser particle size analyzer, and superconducting quantum interference device magnetometer were used to analyze the physical and chemical properties of the Fe3O4 and Tc-99-Fe3O4 nanoparticles. The biodistribution and excretion of Tc-99m-Fe3O4 were also investigated. Radiochemical analyses showed that the labeling efficiency was over 92% after 1 min in the presence of a reducing agent. Hydroxyl and amine groups covered the surface of the Fe3O4 particles. Therefore, Tc-99 (VII) reduced to lower oxidation states and might bind to Fe3O4 NPs. The sizes of the Tc-99-Fe3O4 NPs were about 600 nm without ultrasound vibrations, and the particle sizes were reduced to 250 nm under ultrasound vibration conditions. Nonetheless, Fe3O4 NPs and Tc-99-Fe3O4 NPs exhibited superparamagnetic properties, and the saturation magnetization values were about 55 and 47 emu/g, respectively. The biodistribution showed that a portion of the Tc-99m-Fe3O4 nanoparticles might embolize in a pulmonary capillary initially; the embolism radioactivity was cleared from the lungs and was then taken up by the liver. Tc-99m-Fe3O4 metabolized very slowly only 1-2% of the injected dose (ID) was excreted in urine and about 2.37% ID/g was retained in the liver 4 h after injection. Radiopharmaceutically, Tc-99m-Fe3O4 NPs displayed long-term retention, and only Tc-99m-Fe3O4 NPs that dissociated to free pertechnetate could be excreted in urine. This research evaluated the feasibility of non-polymer magnetic ferrite NPs labeled with technetium as potential radiopharmaceuticals in nuclear medicine.