Intrinsically 69Ge-Labeled Gum Arabic Glycoprotein-Coated Gallium Oxide Nanoparticles: A New Nanoprobe for PET Imaging

The synthesis of nanoradiopharmaceuticals is one of the biggest scientific breakthroughs in nuclear medicine, which harnesses the synergistic capabilities of nanotechnology and radiochemistry for cancer diagnostics and therapy with markedly enhanced efficacy. Production of exotic radionuclides and development of robust radiolabeling methods for their incorporation in the synthesized nanoparticles (NPs) play pivotal roles in this endeavor. Herein, we report the production of an emerging positron emission tomography (PET) radionuclide, germanium-69 (Ge-69; T-1/2 = 39.05 h, 21% beta(+), E-max = 1205 keV), via a Ga-nat (p, n) Ge-69 reaction using a particle accelerator and conversion of the irradiated target into intrinsically Ge-69-labeled gallium oxide NPs functionalized in gum arabic glycoprotein (Ge-69:Ga2O3-GA NPs). As-synthesized NPs were extensively characterized, and they demonstrated excellent colloidal and radiochemical stabilities. As a proof of concept, Ge-69:Ga2O3-GA NPs were administered intravenously in healthy Wistar rats, and PET imaging at 2 h postinjection (p.i.) demonstrated accumulation of NPs in the liver and clearance through the hepatobiliary route, establishing the in vivo stability of the intrinsically radiolabeled NPs. Also, when Ge-69:Ga2O3-GA NPs were administered in the footpad of Wistar rats, accumulation of NPs in the popliteal lymph node could clearly be seen at 2 h p.i., demonstrating their potential in noninvasive sentinel lymph node (SLN) mapping. Overall, this strategy of the synthesis of intrinsically radiolabeled functionalized NPs might pave the way toward more specific and individualized cancer care.

Automated summary

The synthesis of nanoradiopharmaceuticals, which combines nanotechnology and radiochemistry, has significantly enhanced the efficacy of cancer diagnostics and therapy. This study reports the production of a new positron emission tomography radionuclide, germanium-69, and its successful incorporation into synthesized nanoparticles. The in vivo stability and accumulation of these nanoparticles in liver and lymph nodes indicate their potential for more specific and individualized cancer care.