Improving the Effect of Cancer Cells Irradiation with X-rays and High-Energy Protons Using Bimetallic Palladium-Platinum Nanoparticles with Various Nanostructures

SIMPLE SUMMARY: Radiation-based anticancer therapies are often ineffective as cancer cells may acquire radioresistance. Moreover, such therapies can cause unwanted side effects, affecting normal tissues. This problem may be remedied by the use of nanometric radiosensitizers. These compounds in non-toxic concentrations improve the effectiveness of therapy while reducing the total dose of radiation used. In this work, we checked the radiosensitizing properties of bimetallic palladium-platinum nanoparticles with different nanostructures: nano-alloy and core-shell. It has been found that nano-alloy structures are more promising radiosensitizers in vitro, and their effect is more satisfactory when using X-rays than high-energy protons. Thus, by appropriately designing the microstructure of nanomaterials, it is possible to modulate their radiosensitizing potential and enhance the therapy′s effectiveness. ABSTRACT: Nano-sized radiosensitizers can be used to increase the effectiveness of radiation-based anticancer therapies. In this study, bimetallic, ~30 nm palladium-platinum nanoparticles (PdPt NPs) with different nanostructures (random nano-alloy NPs and ordered core-shell NPs) were prepared. Scanning transmission electron microscopy (STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS), zeta potential measurements, and nanoparticle tracking analysis (NTA) were used to provide the physicochemical characteristics of PdPt NPs. Then, PdPt NPs were added to the cultures of colon cancer cells and normal colon epithelium cells in individually established non-toxic concentrations and irradiated with the non-harmful dose of X-rays/protons. Cell viability before and after PdPt NPs-(non) assisted X-ray/proton irradiation was evaluated by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Flow cytometry was used to assess cell apoptosis. The results showed that PdPt NPs significantly enhanced the effect of irradiation on cancer cells. It was noticed that nano-alloy PdPt NPs possess better radiosensitizing properties compared to PtPd core-shell NPs, and the combined effect against cancer cells was c.a. 10% stronger for X-ray than for proton irradiation. Thus, the radio-enhancing features of differently structured PdPt NPs indicate their potential application for the improvement of the effectiveness of radiation-based anticancer therapies.