Abstract: The aim of the study was to investigate the toxic effects of nanosized ZnO in vitro. Characterization of ZnO nanoparticles was carried out by atomic force microscope (AFM), transmission electron microscope (TEM) and X-ray diffraction (XRD). In this study, lung cancer cell lines A549 were exposed to 0mmol/L, 0.1mmol/L, 0.5mmol/L, 1mmol/L, 5mmol/L, 10mmol/L of ZnO nanoparticles, respectively. MTT assay was performed to evaluate the viabilities of ZnO-treated cells after 12h, 24h, 36h and 48h exposure. The activities of lactate dehydrogenase (LDH), cellular superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were determined after exposure to 1mmol/L ZnO for 24 h. Moreover, apoptotic characteristics and reactive oxygen species (ROS) production in A549 cells were measured. ZnO nanoparticles were needlelike crystals (75 nm length; 20 nm diameter). The viability of A549 cells were reduced after exposure to ZnO nanoparticles in a dose-dependent manner. The activities of LDH and the levels of MDA were significantly increased (P < 0.05, P < 0.01), respectively. However, the activities of CAT were significantly decreased (P < 0.01). No significant difference in the activities of SOD was observed between the ZnO-treated cells and the controls. ZnO nanoparticles at 1mmol/L induced apoptosis in A549 cells. The levels of ROS in ZnO-treated cells were significantly higher than that in controls. These results suggested that ZnO nanoparticles could result in apoptosis in A549 cells through oxidative stress.

Key words: ZnO nanoparticles, human lung cancer cell lines A549, cytotoxicity