Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure that uses special drugs or compounds, called photosensitizing agents. The photosensitizers have been activated by certain kinds of lights and they can kill cancer cells selectively through the generation of reactive oxygen species (ROS) [1, 2]. ZnO is a semiconducer material that has photosensitizing effects and generates ROS. In this study, zinc oxide/hydroxyapatite (ZnO/HAP) nanocomposites were synthesized by the hydrothermal method and characterized by FT-IR and UV-visible spectroscopy. Then, the cytotoxic effect of ZnO/HAP nanoparticles on the viability of osteosarcoma cells (Saos-2 cells) was evaluated in the presence and absence of UV irradiation. MTT assay revealed that ZnO/HAP nanoparticles decreased the viability of Saos-2 cells in a dose-dependent manner; however, a significant reduction in cell viability was observed since ZnO/HAP-treated cells were exposed to UV irradiation. The phase contrast microscopic examination of the cells treated with the ZnO/HAP nanoparticles revealed growth inhibition and the typical morphological features of dead cells, however, these phenomena were significantly increased as cells treated with both nanoparticles and UV irradiation. Based on these findings, ZnO/HAP nanoparticles could be considered as a novel photosensitizer which can be employed for cancer therapy.

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