Silver nanoparticles outperform gold nanoparticles in radiosensitizing U251 cells in vitro and in an intracranial mouse model of glioma

Abstract

Radiotherapy performs an important function in the treatment of cancer, but resistance of tumor cells to radiation still remains a serious concern. More research on more effective radiosensitizers is urgently needed to overcome such resistance and thereby improve the treatment outcome. The goal of this study was to evaluate and compare the radiosensitizing efficacies of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) on glioma at clinically relevant megavoltage energies. Both AuNPs and AgNPs potentiated the in vitro and in vivo antiglioma effects of radiation. AgNPs showed more powerful radiosensitizing ability than AuNPs at the same mass and molar concentrations, leading to a higher rate of apoptotic cell death. Furthermore, the combination of AgNPs with radiation significantly increased the levels of autophagy as compared with AuNPs plus radiation. These findings suggest the potential application of AgNPs as a highly effective nano-radiosensitizer for the treatment of glioma.

Keywords:

• gold nanoparticles
• silver nanoparticles
• radiosensitization
• glioma
• apoptosis
• autophagy

Supplementary materials

Figure S1 Cytotoxicity of AuNPs and AgNPs on 184B5 human mammary epithelial cells.

Notes: The cell viability was determined using a CCK-8 assay after a 24-hour exposure of AuNPs or AgNPs at multiple concentrations. Data are a summary of three independent experiments and expressed as mean ± SD.

Abbreviations: AgNPs, silver nanoparticles; AuNPs, gold nanoparticles; CCK-8, Cell Counting Kit-8; SD, standard deviation.

Figure S2 Effects of citrate-coated and naked AgNPs on U251 glioma cell viability with or without radiation.

Notes: Cells were incubated for 24 hours with varying concentrations of AgNPs. At 24 hours after radiation treatment, the cell viability was determined using a CCK-8 assay. Data are a summary of three independent experiments and expressed as mean ± SD.

Abbreviations: AgNPs, silver nanoparticles; CCK-8, Cell Counting Kit-8; SD, standard deviation.

Figure S3 Effects of AuNPs and AgNPs plus radiation on 184B5 epithelial cell viability.

Notes: Cells were incubated for 24 hours with 10 μg/mL AuNPs or AgNPs. At 24 hours after radiation treatment, the cell viability was determined using a CCK-8 assay. Data are a summary of three independent experiments and expressed as mean ± SD.

Abbreviations: AgNPs, silver nanoparticles; AuNPs, gold nanoparticles; CCK-8, Cell Counting Kit-8; SD, standard deviation.

Acknowledgments

This work was supported by the National Key Basic Research Program of China (973 Program; 2013CB933904), the National Natural Science Foundation of China (81571805, 81471783), and the Talents Planning of Six Summit Fields of Jiangsu Province (WSN-055). We are grateful for the support from the Collaborative Innovation Center of Suzhou Nano Science and Technology.

Disclosure

The authors report no conflicts of interest in this work.