Radiopharmaceutical properties of hydroxyapatite smaller than 50nm produced from eggshell and labeled with 99mTc and its biodistribution in rabbits.

Objective: Radiolabeling of nanoparticles has potential benefits for personalized treatments and theranostic applications, which have been on the agenda in recent years. Hydroxyapatite nanoparticles (HANP), which have a great similarity to bone tissue, stand out as a biocompatible nanoparticle. The different biodistribution properties of hydroxyapatite molecules in different nanosizes may create new opportunities for their use, especially in bone imaging and in the treatment of bone tumors. This study aims to investigate the labeling of hydroxyapatite molecules smaller than 50 nanometers obtained from eggshells with technetium-99m (^99mTc) and the in vivo distribution of this molecule in rabbits.

Materials and methods: Characterization of nanohydroxyapatite particles obtained from eggshells was performed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). Radiolabeling of HANP smaller than 50nm with ^99mTc radionuclide, stability of the labeled product, and biodistribution profile in rabbits were investigated.

Results: The radiochemical purity of the ^99mTc-HANP was obtained as 96%. The in vitro stability of ^99mTc labeled HANP was examined for up to 12 hours and showed excellent in vitro stability for the first 4 hours in saline. Technetium-99m-HANP remained stable in vivo during the 6-hour imaging period. In quantitative analysis, ^99mTc-HANP showed accumulation in bone tissue in the second hour.

Conclusion: Technetium-99m-HANP nanoradiopharmaceuticals with sizes less than 50 nanometers (20-31nm) showed high uptake in bone tissue in rabbits. Therefore, HANP can be developed as imaging radiopharmaceuticals in bone tissue and bone cancers.