Efficacy of 15 nm Gold Nanoparticles for Image-Guided Gliosarcoma Radiotherapy

Targeted brain cancer treatments are sorely needed to improve long-term prognosis, particularly for gliosarcoma and glioblastoma patients. Gold nanoparticles (GNPs) have unique properties including high atomic number, biocompatibility, and small size for cancer cell internalization. GNPs are consequently an ideal candidate for improved cancer targeting using image-guided radiotherapy. This work investigated 15 nm AuroVistTM GNPs for image-guided gliosarcoma radiotherapy and identified optimum GNP concentrations. The GNPs were found to be 15–20 nm using optical surface plasmon resonance absorption, with a (41.3 ± 0.3) nm hydrodynamic diameter. Confocal imaging showed that 50–500 µg/mL of the GNPs was well-internalized into the 9L cells within 24–48 h. γ-H2AX assays showed that 50–500 µg/mL of the GNPs radiosensitized the 9L cells irradiated with 125 and 150 kVp X-rays. However, only 500 µg/mL of the GNPs produced significant long-term dose enhancement with 150 kVp X-rays (with a sensitization enhancement ratio at 10% survival of 1.43, and 1.13 with 50 µg/mL) using clonogenic assay. CT imaging of the GNPs in the 9L tumors in Fischer rats further showed that GNP concentrations above 500 µg/mL were required to distinguish the tumor from the brain, and the GNPs were detected 48 h after injection. These promising results indicate that the GNPs can be used for selective gliosarcoma treatment with image-guided X-ray radiotherapy at concentrations above 500 µg/mL.