Effect of the porosity of the palladium shell in Au-core Pd-shell bimetallic nanoparticles for the radiosensitizing properties in simulated anticancer proton radiotherapy.

The combination of radiotherapy and metallic nanoparticles (NPs) turns out to be a promising option for cancer treatment. Currently, proton radiotherapy (PRT) is becoming more and more popular. Compared to classic X-ray radiotherapy, PRT is characterized by similar treatment effectiveness while minimizing off-target effect. The purpose of this study was to synthesize and evaluate two types of bimetallic gold-palladium nanoparticles (AuPd NPs), that differ in the porosity of the palladium shell (non-porous AuPd CSs - core-shells and porous AuPd NRs - nanoraspberries), as radiosensitizers to improve the efficiency of proton irradiation. Importantly, both types of crystalline AuPd NPs had a similar shape (spherical) and size (⁓ 20 nm). The results of in vitro cell viability tests indicated similar cytotoxicity of both types of AuPd NPs towards selected cancer cell lines, as well as promising radiosensitizing potential in simulated PRT, especially for porous AuPd NRs. Moreover, holotomographic microscopy analysis showed that AuPd NPs at a low concentration of 75 μg/ml cause in culture detachment of low-aggressive SW480 colon cancer cells, but do not affect growth of aggressive HCT116 cancer cells and normal CRL-1790 epithelial cells in vitro. These results can open new perspectives on the further applications of NPs as radiosensitizers.