Abstract
BackgroundIt has been shown that nanomaterials (NMs) are able to translocate to secondary tissues one of the important being the kidneys. Oxidative stress has been implicated as a possible mechanism for NM toxicity, hence effects on the human renal proximal tubule epithelial cells (HK-2) treated with a panel of engineered nanomaterials (NMs) consisting of two zinc oxide particles (ZnO - coated - NM 110 and uncoated - NM 111), two multi walled carbon nanotubes (MWCNT) (NM 400 and NM 402), one silver (NM 300) and five TiO2 NMs (NM 101, NRCWE 001, 002, 003 and 004) were evaluated.MethodsIn order to assess the toxicological impact of the engineered NMs on HK-2 cells - WST-1 cytotoxicity assay, FACSArray, HE oxidation and the comet assays were utilised. For statistical analysis, the experimental values were compared to their corresponding controls using an ANOVA with Tukey’s multiple comparison.ResultsWe found the two ZnO NMs (24 hr LC50 – 2.5 μg/cm2) and silver NM (24 hr LC50 – 10 μg/cm2) were highly cytotoxic to the cells. The LC50 was not attained in the presence of any of the other engineered nanomaterials (up to 80 μg/cm2). All nanomaterials significantly increased IL8 and IL6 production. Meanwhile no significant change in TNF-α or MCP-1 was detectable. The most notable increase in ROS was noted following treatment with the Ag and the two ZnO NMs. Finally, genotoxicity was measured at sub-lethal concentrations. We found a small but significant increase in DNA damage following exposure to seven of the ten NMs investigated (NM 111, NRCWE 001 and NRCWE 003 being the exception) with this increase being most visible following exposure to Ag and the positively charged TiO2.ConclusionsWhile the NMs could be categorised as low and highly cytotoxic, sub-lethal effects such as cytokine production and genotoxicity were observed with some of the low toxicity materials.
Highlights
It has been shown that nanomaterials (NMs) are able to translocate to secondary tissues one of the important being the kidneys
In order to investigate if the nanomaterials behaved differently in K-SFM or RPMI-FCS, the hydrodynamic size distributions and zeta potential of the NMs dispersed in the two media was measured between a 1–128 μg/ml concentration range by Dynamic Light Scattering (DLS) (Table 1)
It is widely accepted that DLS is not a suitable method of ascertaining the size of carbon nanotubes, we examined how the two multi walled carbon nanotubes (MWCNT) behave in our two chosen media utilising light microscopy
Summary
It has been shown that nanomaterials (NMs) are able to translocate to secondary tissues one of the important being the kidneys. The prefix “nano” was coined for particles containing tens or hundreds of atoms, with dimensions at the scale of less than 100 nm [1]. It is this small size which is fundamental to the field of nanotechnology, other physicochemical properties influence the physical, biological and toxicological properties of these manufactured materials [2]. A thorough risk evaluation is urgently required to provide an improved understanding of the implication of exposure to different NMs and any potential threat to humans or the environment [6]. It is necessary to identify the hazards associated with NM exposure both in vitro and in vivo, to assemble a knowledge base on the potential toxicity associated with NM exploitation on human health [4]
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