Extensive uses of calcium titanate nanoparticles (CaTiO3-NPs) and erbium oxide nanoparticles (Er2O3-NPs) increase their release into the environment and human exposure, particularly through skin contact. However, there are almost no studies available on the effect of these nanoparticles on skin integrity. Therefore, this study was undertaken to estimate CaTiO3-NP- or Er2O3-NP-induced cytotoxicity and genotoxicity in normal human skin fibroblast (HSF) cells. Cell viability was measured using sulforhodamine B (SRB) assay, while the level of DNA damage was detected using the alkaline comet assay. The intracellular levels of reactive oxygen species (ROS) as well as the expression level of p53, Bax, and Bcl2 genes were detected. Although the viability of HSF cells was non-markedly changed after 24 h, prolonged treatment with CaTiO3-NPs or Er2O3-NPs for 72 h induced concentration-dependent death of HSF cells. Treatment of normal HSF cells with IC50/72 h of CaTiO3-NPs or Er2O3-NPs did not cause marked changes in the intracellular level of ROS, DNA damage parameters, and expression levels of apoptosis genes compared to their values in the untreated HSF cells. We thus concluded that CaTiO3-NPs or Er2O3-NPs cause time- and concentration-dependent cytotoxicity toward normal HSF cells. However, safe and non-genotoxic effects were demonstrated by the apparent non-significant changes in intracellular ROS level, DNA integrity, and apoptotic genes’ expression after exposure of normal HSF cells to nanoparticles. Thus, it is recommended that further studies be conducted to further understand the toxic and biological effects of CaTiO3-NPs and Er2O3-NPs.

The remarkable physical and chemical characteristics of noble metal nanoparticles, such as high surface-to-volume ratio, broad optical properties, ease of assembly, surfactant and functional chemistry, have increased scientific interest in using erbium oxide nanoparticles (Er2O3-NPs) and other noble metal nanostructures in cancer treatment. However, the therapeutic effect of Er2O3-NPs on hepatic cancer cells has not been studied. Therefore, the current study was conducted to estimate the therapeutic potential of Er2O3-NPs on human hepatocellular carcinoma (Hep-G2) cells. Exposure to Er2O3-NPs for 72 h inhibited growth and caused death of Hep-G2 cells in a concentration dependent manner. High DNA damage and extra-production of intracellular reactive oxygen species (ROS) were induced by Er2O3-NPs in Hep-G2 cells. As determined by flow cytometry, Er2O3-NPs arrested Hep-G2 cell cycle at the G0/G1 phase and markedly increased the number of Hep-G2 cells in the apoptotic and necrotic phases. Moreover, Er2O3-NPs caused simultaneous marked increases in expression levels of apoptotic (p53 and Bax) genes and decreased level of anti-apoptotic Bcl2 gene expression level in Hep-G2 cells. Thus it is concluded that Er2O3-NPs inhibit proliferation and trigger apoptosis of Hep-G2 cells through the extra ROS generation causing high DNA damage induction and alterations of apoptotic genes. Thus it is recommended that further in vitro and in vivo studies be carried out to study the possibility of using Er2O3-NPs in the treatment of cancer.