Abstract
Conventional photodynamic therapy (PDT) is limited by its penetration depth due to the photosensitizer and light source. In this study, we developed X-ray induced photodynamic therapy that applied X-ray as the light source to activate Ce-doped CaCO&sub3; (CaCO&sub3;:Ce) to generate an intracellular reactive oxygen species (ROS) for killing cancer cells. The A549 cell line was used as the in vitro and in vivo model to evaluate the efficacy of X-ray-induced CaCO&sub3;:Ce. The cell viability significantly decreased and cell cytotoxicity obviously increased with CaCO&sub3;:Ce exposure under X-ray irradiation, which is less harmful than radiotherapy in tumor treatment. CaCO&sub3;:Ce produced significant ROS under X-ray irradiation and promoted A549 cancer cell death. CaCO&sub3;:Ce can enhance the efficacy of X-ray induced PDT, and tumor growth was inhibited in vivo. The blood analysis and hematoxylin and eosin stain (H & E) stain fully supported the safety of the treatment. The mechanisms underlying ROS and CO&sub2; generation by CaCO&sub3;:Ce activated by X-ray irradiation to induce cell toxicity, thereby inhibiting tumor growth, is discussed. These findings and advances are of great importance in providing a novel therapeutic approach as an alternative tumor treatment.