New CeF3-ZnO nanocomposites for self-lighted photodynamic therapy that block adenocarcinoma cell life cycle

Lay summary: We developed a nanocomposite (NC) structure, made of inorganic materials, and we show that it can be used to enhance desired effects in tumor x-ray radiotherapy, hence helping to reduce radiotherapy's negative side effects. The rationale of this novel NC is to couple a material capable of capturing the high energy of x-rays, and transfer this energy to another material, which is an efficient generator of chemical species used to kill cancer cells. This NC was successfully tested on human adenocarcinoma cells, a standard benchmark for this kind of applications.

Aim: To synthesize and characterize the performances of a new all-inorganic nanocomposite (NC) for self-lighted photodynamic therapy against cancer. This NC could allow radiotherapy doses to be reduced, as it enhances the effects of x-rays, generating cytotoxic reactive oxygen species as singlet oxygen. Materials & methods: The proposed NC combines CeF3 and ZnO; CeF3 absorbs 6-MeV x-rays and activates the photosensitizer ZnO. Characterization is performed by transmission electron microscopy (TEM), scanning-TEM, energy dispersive x-ray spectrometry and fluorescence spectroscopies. Efficiency on human adenocarcinoma cells (A549) was tested by fluorescence spectroscopy, cytofluorimetry, viability assays, clonogenic assays, cell cycle progression assays. Results: NC blocks A549's cell cycle before mitosis in the dark. Upon low-dose x-ray irradiation (2Gy), reactive oxygen species/singlet oxygen are generated, further blocking cell cycle and reducing viability by 18% with respect to the sum of x-ray irradiation and NC dark activity. Conclusion: These novel NCs promise to reduce doses in radiotherapy, helping to reduce unwanted side effects.