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X-ray induced cytotoxicity of aqueous colloidal solutions of UV-C luminescent La1−xPrxPO4 nanoparticles
The use of UV-C radiation for the treatment of tumors is a stand-alone therapeutic intervention that can induce cellular apoptosis and is independent of photosensitizer or oxygen concentration in tumor. To explore the potential of using X-ray excited UV-C luminescent nanoparticles as a basis for creating drugs to improve radiation therapy, two colloidal solutions of monoclinic La1–xPrxPO4 nanoparticles with different morphologies of large nanofibers (x = 0.02) or small nanorods (x = 0.05) were prepared using a microwave-assisted hydrothermal method. Comparison of X-ray excited UV-C luminescence of colloidal solutions showed approximately 6.3 times higher brightness for larger nanoparticles. The intrinsic and X-ray-induced cytotoxicity of the prepared colloidal solutions on the viability of cancerous Mh22a and healthy L929 cell cultures were studied using MTT assay and fluorescence microscopy. Fluorescence microscopy showed differences in the types of cell death (apoptosis or necrosis) after incubation with nanofiber or nanorod samples. X-ray irradiation was performed in two modes with different voltage on the X-ray tube (50 and 80 kV) and the same radiation dose (8 Gy). Groups of cells incubated with nanoparticles and irradiated with 50 kV mode showed greater death rate. According to MTT analysis, irradiation of cells incubated with La0.98Pr0.02PO4 nanofibers at a concentration of 2 mg/mL reduced survival by 20-30%, and at the same time, according to fluorescence microscopy data, the number of cells undergoing apoptosis exceeded the number of cells that died through necrosis and reached 50-70%. Quantitative analysis of the relative number of dead cells caused by X-ray-induced cytotoxicity of La0.95Pr0.05PO4 nanorods did not reveal statistically significant results in reducing cell viability.