Multimodal Radiobioconjugates of Magnetic Nanoparticles Labeled with ⁴⁴Sc and ⁴⁷Sc for Theranostic Application

This study was performed to synthesize multimodal radiopharmaceutical designed for the diagnosis and treatment of prostate cancer. To achieve this goal, superparamagnetic iron oxide (SPIO) nanoparticles were used as a platform for targeting molecule (PSMA-617) and for complexation of two scandium radionuclides, ⁴⁴Sc for PET imaging and ⁴⁷Sc for radionuclide therapy. TEM and XPS images showed that the Fe₃O₄ NPs have a uniform cubic shape and a size from 38 to 50 nm. The Fe₃O₄ core are surrounded by SiO₂ and an organic layer. The saturation magnetization of the SPION core was 60 emu/g. However, coating the SPIONs with silica and polyglycerol reduces the magnetization significantly. The obtained bioconjugates were labeled with ⁴⁴Sc and ⁴⁷Sc, with a yield higher than 97%. The radiobioconjugate exhibited high affinity and cytotoxicity toward the human prostate cancer LNCaP (PSMA+) cell line, much higher than for PC-3 (PSMA-) cells. High cytotoxicity of the radiobioconjugate was confirmed by radiotoxicity studies on LNCaP 3D spheroids. In addition, the magnetic properties of the radiobioconjugate should allow for its use in guide drug delivery driven by magnetic field gradient.