In vitro toxicity studies of zinc oxide nano- and microrods on mammalian cells: A comparative analysis

This study aims at investigating the cytotoxicity of zinc oxide nanorods (ZnO-NR) and microrods (ZnO-MR) in two different human cell lines. The materials were produced by a simple and cost-effective hydrothermal route and induced a slight dose dependent toxic effect on MCF7 and HaCaT cells. Both cell lines showed a very low cytotoxicity when exposed to suspensions containing 1-100 μg/ml of ZnO-NR and ZnO-MR. Moreover, Field-emission scanning electron microscopy (FE-SEM) images of both cell lines exposed to the materials showed no significant effect on cell morphology compared to untreated cells. However, the treatments induced modifications of filopodia, mainly in MCF7 cells exposed to ZnO-NR. In addition, a very slight increase in ROS generation was observed only in ZnO-MR-treated cells. Moreover, an apoptotic effect of ZnO-NR rather than a cell cycle arrest was observed in MCF7 cells after treatment. Overall the cytotoxicity in in vitro systems reflects a biocompatibility of both ZnO-NR and ZnO-MR, representing powerful tools in several applications.