Ultrafine PVP-stabilized platinum nanoparticles for megavoltage X-ray radiosensitization of MCF-7 cells: synthesis, characterization, and free quercetin co-treatment

Ultrafine polyvinylpyrrolidone-stabilized platinum nanoparticles (PVP-Pt NPs) were produced using a single-step hydrothermal route and investigated as candidate nanoradiosensitizers for megavoltage X-ray treatment of MCF-7 breast cancer cells. Their performance was examined both independently and during concurrent treatment with free quercetin (Que). Transmission electron microscopy (TEM) showed approximately spherical Pt nanoparticles, while quantitative TEM image analysis yielded particle diameters of approximately 3–6 nm with a mean diameter of ~ 4.5 nm. Scanning electron microscopy (SEM) showed a smooth and homogeneous surface without pronounced agglomeration or cracking, consistent with a stabilizing role of PVP in limiting particle coalescence. X-ray diffraction showed reflections consistent with crystalline face-centered cubic (FCC) platinum with the Fm-3 m space group. FTIR spectroscopy showed spectral features consistent with possible interactions between PVP functional groups and Pt species. The optical response was evaluated by UV–visible spectroscopy. The cytotoxic and radiation-associated effects of PVP-Pt NPs, free Que, and concurrent PVP-Pt + Que treatment were evaluated at concentrations of 0.1, 1, 10, and 100 µg/mL, with and without megavoltage X-ray irradiation at 2 and 4 Gy. Without irradiation, significant reductions in MTT-derived cell viability were observed for PVP-Pt and concurrent PVP-Pt + Que treatment at 10 and 100 µg/mL, whereas the overall effect of free Que concentration was not statistically significant. Among the investigated formulations, PVP-Pt NPs produced the greatest reduction in MCF-7 cell viability following irradiation. At 10 µg/mL mean MTT-derived cell viability was approximately 45.4% under 2 Gy and 38.6% under 4 Gy irradiation. These findings support further investigation of ultrafine PVP-Pt nanoparticles as candidate nanoradiosensitizers for enhancing radiation-associated cytotoxicity in MCF-7 breast cancer cells.