Synthesis and characterization of holmium acetylacetonate nanoparticles for nuclear medicine applications

Holmium-loaded AcAc nanoparticles are potential agents for radionuclides endoradiotherapy because of their low density, biodegradability and favorable radiation characteristics. In this study, production, quality control and biodistribution studies of 166</sup>Ho-AcAc nanoparticles have been presented. Firstly, the stable 165</sup>Ho acetylacetonate (AcAc) spheres were prepared by the solvent evaporation technique. The 165</sup>Ho-AcAc nanoparticles were converted to the 166</sup>Ho-AcAc by irradiation in the Tehran Research Reactor. The morphology, stability, and structural parameters of the complex were investigated by SEM, ITLC, IR and XRD, respectively. The complex solutions (100 μCi/100 μl) were injected intra-tail into rat followed by scarification studies post- injection. The results indicated that the 166</sup>Ho-AcAc nanoparticles were prepared successfully with an optimal mean particle size of 70-100 nm and displayed a smooth surface with a high radiochemical purity of more than 97%. The complex was stable at 4ºC, human serum, PBS buffer, and room temperature. The most upper %ID/g of the 166</sup>Ho-AcAc nanoparticles was observed in the liver. Our data showed that the AcAc nanoparticles could be made in the optimal size range for the laser irradiation, and their ability to retain 166</sup>Ho makes them attractive agents for endoradiotherapy.