David Ramos

Cytotoxicity and Genotoxicity of Ceria Nanoparticles on Different Cell Lines in Vitro

Owing to their radical scavenging and UV-filtering properties, ceria nanoparticles (CeO2-NPs) are currently used for various applications, including as catalysts in diesel particulate filters. Because of their ability to filter UV light, CeO2-NPs have garnered significant interest in the medical field and, consequently, are poised for use in various applications. The aim of this work was to investigate the effects of short-term (24 h) and long-term (10 days) CeO2-NP exposure to A549, CaCo2 and HepG2 cell lines. Cytotoxicity assays tested CeO2-NPs over a concentration range of 0.5 μg/mL to 5000 μg/mL, whereas genotoxicity assays tested CeO2-NPs over a concentration range of 0.5 μg/mL to 5000 μg/mL. In vitro assays showed almost no short-term exposure toxicity on any of the tested cell lines. Conversely, long-term CeO2-NP exposure proved toxic for all tested cell lines. NP genotoxicity was detectable even at 24-h exposure. HepG2 was the most sensitive cell line overall; however, the A549 line was most sensitive to the lowest concentration tested. Moreover, the results confirmed the ceria nanoparticles’ capacity to protect cells when they are exposed to well-known oxidants such as H2O2. A Comet assay was performed in the presence of both H2O2 and CeO2-NPs. When hydrogen peroxide was maintained at 25 μM, NPs at 0.5 μg/mL, 50 μg/mL, and 500 μg/mL protected the cells from oxidative damage. Thus, the NPs prevented H2O2-induced genotoxic damage.

Luminescent zinc salophen derivatives: cytotoxicity assessment and action mechanism studies

The biological activity of two fluorescent Zn(II)–salophen derivatives has been evaluated. In vitro studies (AFM, emission and UV-vis titration with ethidium bromide and cell growth inhibition) show different mechanisms of interaction with DNA. It has been observed that these compounds enter the cells. Comet assays (with cultured fibroblast cells) have revealed that cellular uptake occurs without damaging the DNA strands. Preliminary studies carried out with living cells have shown IC50 values in a millimolar range, indicative of a non-cytotoxic behaviour. This fact could be understood by confocal microscopy co-localization studies with living cell internalization that have shown that, in fact, the compounds seem to enter the cells but not the nucleus under in vivo conditions.

In Vivo Inflammatory Effects of Ceria Nanoparticles on CD-1 Mouse: Evaluation by Hematological, Histological, and TEM Analysis

The attention on CeO2-NPs environmental and in vivo effects is due to their presence in diesel exhaust and in diesel filters that release a more water-soluble form of ceria NPs, as well as to their use for medical applications. In this work, acute and subacute in vivo toxicity assays demonstrate no lethal effect of these NPs. Anyhow, performing in vivo evaluations on CD-1 mouse systems, we demonstrate that it is even not correct to assert that ceria NPs are harmless for living systems as they can induce status of inflammation, revealed by hematological-chemical-clinical assays as well as histological and TEM microscope observations. TEM analysis showed the presence of NPs in alveolar macrophages. Histological evaluation demonstrated the NPs presence in lungs tissues and this can be explained by assuming their ability to go into the blood stream and lately into the organs (generating inflammation).

Lysine-based surfactants in nanovesicle formulations: the role of cationic charge position and hydrophobicity in in vitro cytotoxicity and intracellular delivery

Abstract Understanding nanomaterial interactions within cells is of increasing importance for assessing their toxicity and cellular transport. Here, the authors developed nanovesicles containing bioactive cationic lysine-based amphiphiles and assessed whether these cationic compounds increase the likelihood of intracellular delivery and modulate toxicity. Different cytotoxic responses were found among the formulations, depending on surfactant, cell line and endpoint assayed. The induction of mitochondrial dysfunction, oxidative stress and apoptosis were the general mechanisms underlying cytotoxicity. Fluorescence microscopy analysis demonstrated that nanovesicles were internalised by HeLa cells and evidenced that their ability to release endocytosed materials into cell cytoplasm depends on the structural parameters of amphiphiles. The cationic charge position and hydrophobicity of surfactants determine the nanovesicle interactions within the cell and, thus, the resulting toxicity and intracellular behaviour after cell uptake of the nanomaterial. The insights into some toxicity mechanisms of these new nanomaterials contribute in reducing the uncertainty surrounding their potential health hazards.