Introduction: Silver nanoparticles (AgNPs) have a wide range of bioactivity, which is highly dependent on particle size, shape, stabilizer, and production method. Here, we present the results of studies of AgNPs cytotoxic properties obtained by irradiation treatment of silver nitrate solution and various stabilizers by accelerating electron beam in a liquid medium. Methods: The results of studies of morphological characteristics of silver nanoparticles were obtained by transmission electron microscopy, UV-vis spectroscopy, and dynamic light scattering measurements. MTT test, alamar blue test, flow cytometry, and fluorescence microscopy were used to study the anti-cancer properties. As biological objects for standard tests, adhesive and suspension cell cultures of normal and tumor origin, including prostate cancer, ovarian cancer, breast cancer, colon cancer, neuroblastoma, and leukemia, were studied. Results: The results showed that the silver nanoparticles obtained by irradiation with polyvinylpyrrolidone and collagen hydrolysate are stable in solutions. Samples with different stabilizers were characterized by a wide average size distribution from 2 to 50 nm and low zeta potential from −7.3 to +12.4 mV. All AgNPs formulations showed a dose-dependent cytotoxic effect on tumor cells. It has been established that the particles obtained with the combination of polyvinylpyrrolidone/collagen hydrolysate have a relatively more pronounced cytotoxic effect in comparison to samples stabilized with only collagen or only polyvinylpyrrolidone. The minimum inhibitory concentrations for nanoparticles were less than 1 μg/mL for various types of tumor cells. It was found that neuroblastoma (SH-SY5Y) is the most susceptible, and ovarian cancer (SKOV-3) is the most resistant to the action of silver nanoparticles. The activity of the AgNPs formulation prepared with a mixture of PVP and PH studied in this work was higher that activity of other AgNPs formulations reported in the literature by about 50 times. Conclusions: The results indicate that the AgNPs formulations synthesized with an electron beam and stabilized with polyvinylpyrrolidone and protein hydrolysate deserve deep study for their further use in selective cancer treatment without harming healthy cells in the patient organism.

The study aimed to assess the radiosensitizing effect of lithium ascorbate on tumor cells. Background: Cancer cells radioresistance is an important factor restraining the success of X-ray therapy. Radiosensitizing drugs make tumor cells more sensitive to ionizing radiation and improve the effectiveness of radiotherapy. Although many chemical substances can potentiate the cytotoxic effects of X-ray radiation, their clinical applications are limited due to possible adverse reactions. Recently, several approaches have been proposed to develop new radiosensitizers that are highly effective and feature low toxicity. Among new enhancers of X-ray therapy, ascorbic acid, and its derivates demonstrate very low toxicity along with a wide therapeutic range. Lithium ascorbate is a promising X-ray therapy enhancer, but its mechanism of action is unknown. This research focuses on the radiosensitizing properties of lithium ascorbate and its effects on both tumor and normal irradiated cells. Methods: The viability of the radiosensitized cells was evaluated by fluorescence flow cytometry using Annexin V-FITC Apoptosis Detection Kit and Cellular ROS Assay Kit (Abcam, UK). The test cell cultures included normal human mononuclear and Jurkat cells. Results: Lithium ascorbate sensitizes normal human mononuclear and Jurkat cells towards ionizing radiation. The combined cytotoxic effect of X-ray irradiation (3 Gy) and lithium ascorbate (1,2 mmol/L) substantially exceeds the effects of the individual factors, i.e. synergetic action appears. The major types of cell death were late apoptosis and necrosis caused by excessive production of reactive oxygen species. Conclusion: Lithium ascorbate in combination with X-ray irradiation exhibited the cytotoxic effect on both normal and cancer lymphoid cells by activating reactive oxygen species (ROS)-induced apoptosis. These findings indicate that lithium ascorbate is a promising substance to develop a new radiosensitizing drug.