Comparative study of the cytotoxic and genotoxic potentials of zinc oxide and titanium dioxide nanoparticles

Abstract

Nanoparticles (NPs) of zinc oxide (ZnO) and titanium dioxide (TiO2) are receiving increasing attention due to their widespread applications. The aim of this study was to evaluate the toxic effect of ZnO and TiO2 NPs at different concentrations (50, 100, 250 and 500 ppm) and compare them with their respective salts using a battery of cytotoxicity, and genotoxicity parameters. To evaluate cytotoxicity, we have used human erythrocytes and for genotoxic studies human lymphocytes have been used as in vitro model species. Concentration dependent hemolytic activity to RBC's was obtained for both NPs. ZnO and TiO2 NPs resulted in 65.2% and 52.5% hemolysis at 250 ppm respectively indicating that both are cytotoxic to human RBCs. Antioxidant enzymes assays were also carried out in their respective hemolysates. Both nanoparticles were found to generate reactive oxygen species (ROS) concomitant with depletion of glutathione and GST levels and increased SOD, CAT and lipid peroxidation in dose dependent manner. ZnO and TiO2 NPs exerted roughly equal oxidative stress in terms of aforementioned stress markers. Genotoxic potential of both the NPs was investigated by in vitro alkaline comet assay. DNA damage induced by the NPs was concentration dependent and was significantly greater than their ionic forms at 250 and 500 ppm concentrations. Moreover, the nanoparticles of ZnO were significantly more genotoxic than those of TiO2 at higher concentrations. The toxicity of these NPs is due to the generation of ROS thereby causing oxidative stress.

Comparative Study of Antidiabetic Activity and Oxidative Stress Induced by Zinc Oxide Nanoparticles and Zinc Sulfate in Diabetic Rats

“…As mentioned above, they found that toxic superoxide radical formation by ZnO nanoparticles was much more than ZnSO 4 . In addition, they observed a dosedependent increase in activity of erythrocyte SOD (46). These data completely match those reported here.…”

“…However, based on their findings, it cannot be generalized that nanoparticles are always more toxic than micrometer particles (45). Further, in a study, the ability of ZnO nanoparticles in generation of different ROS was compared to their respective ionic form and results showed that ZnO nanoparticles hugely release ROS compared to their salt and consistently MDA production by ZnO nanoparticles was more than zinc sulfate (46). The mechanisms by which zinc protects against lipid peroxidation and ROS generation have not yet been completely elucidated.…”

In vitro comparative cytotoxicity study of aminated polystyrene, zinc oxide and silver nanoparticles on a cervical cancer cell line

“…Due to the vast differences in their physico-chemical properties, primarily resultant from their differing synthesis methods, they are known to induce adverse effects in biological systems. NPs can interfere with cellular systems by the NPs interaction's with proteins, DNA, lipids, membrane, organelles, and biological fluids (Roiter et al 2008, Shang et al 2014, Khan et al 2015. Due to their reduced size (1-100 nm) and large surface area to volume ratio, they can easily cross cell membranes (Khan et al 2015) and further enter the bloodstream reaching different organs (Vishwakarma et al 2010).…”

“…NPs can interfere with cellular systems by the NPs interaction's with proteins, DNA, lipids, membrane, organelles, and biological fluids (Roiter et al 2008, Shang et al 2014, Khan et al 2015. Due to their reduced size (1-100 nm) and large surface area to volume ratio, they can easily cross cell membranes (Khan et al 2015) and further enter the bloodstream reaching different organs (Vishwakarma et al 2010). Their interactions with the culture medium or biological fluids have also been reported to be an important consideration for their toxicological evaluation due to the increased probability of aggregation upon dispersion in these environments, which is known to influence their cellular uptake with a subsequent impact on their toxicity (De Matteis 2017).…”

“…Although the underlying mechanism of NPs induced cytotoxicity is not fully understood, oxidative stress, lipid peroxidation, and reduced glutathione (GSH) levels have been reported to play important roles in inducing DNA damage, apoptosis, cell membrane disruption, and ultimately cell death (Hussain et al 2005, Piao et al 2011, Singh and Ramarao 2012, Govender et al 2013, Khan et al 2015. In the study presented here, the in vitro cytotoxic response of AmPs, ZnO, and Ag NPs in HeLa cells was studied, the physiochemical characteristics of NPs have previously been shown to play an important role in the toxicological investigation (Mukherjee et al 2012) and will be studied in conjunction with the in vitro screening here.…”