Graphene Oxide Nanoparticels Interaction with Jurkat Cell Line in Cell-IQ System

In vitro evaluation of the toxicity mechanisms of two functionalized reduced graphene oxide derivatives

Dodecyl amine functionalized reduced graphene oxide (DA-rGO) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride functionalized rGO (MTAC-rGO) have been developed and characterised for their further use in the food packaging industry as food contact materials. But before their application, an authorization procedure is required in which their safety plays a key role. Therefore, the aim of this work was to evaluate their toxicity with focus on two different toxicity mechanisms: genotoxicity and immunotoxicity. Following the recommendations of the European Food Safety Authority, the mutagenicity and genotoxicity were evaluated by the mouse lymphoma assay and the micronucleus assay, respectively, in L5178Y TK cells. Both assays did not show any effect at the tested concentrations (up to 200 μg/mL). The potential immunotoxicity was evaluated on two human cell lines: THP-1 (monocytes) and Jurkat (lymphocytes). The results showed that the highest cytotoxicity was induced by MTAC-rGO in Jurkat cells. The two functionalized rGO compounds did not significantly affect the differentiation process of monocytes into macrophages. In general, both compounds altered the expression of different cytokines, with the most prominent changes observed with MTAC-rGO in THP-1 cells. Moreover, MTAC-rGO induced the most evident differences in markers of cell death mechanisms. Also, for this graphene derivative, increased levels of IL-1β and TNF-α in THP-1 cell supernatants were observed by ELISA. In conclusion, a case-by-case evaluation is necessary as both functionalized rGO compounds exhibit distinct toxicity profiles that warrant further investigation before their application in the food industry.

Effect of PEGylated Graphene Oxide Nanoparticles on the Metabolism of Jurkat Cells

The effect of graphene oxide (GO) nanoparticles of 100-200 nm in size coated with linear (LP-GO) and branched (BP-GO) polyethylene glycol at concentrations of 5 and 25 μg/mL on the metabolism of Jurkat tumor cells was studied. It was found that LP-GO nanoparticles at a concentration of 25 μg/mL can enhance basal glycolysis of Jurkat T-lymphocyte tumor cell line cells, while LP-GO and BP-GO at the same concentration can reduce the indicators of compensatory glycolysis. Despite this, GO nanoparticles coated with linear and branched PEG at a concentration of 5 μg/mL do not have pronounced effects on oxidative phosphorylation and glycolysis of Jurkat cells and could therefore be safe for activated T cells.

Interaction of Graphene Oxide Nanoparticles with Human Mononuclear Cells in the Cell-IQ System

The interaction of graphene oxide nanoparticles with human peripheral blood mononuclear cells was studied using the Cell-IQ continuous monitoring system for living cells. We used graphene oxide nanoparticles of various sizes coated with linear or branched polyethylene glycol (PEG) in concentrations of 5 and 25 μg/ml. After 24-h incubation with graphene oxide nanoparticles, the increase in the number of peripheral blood mononuclear cells at visualization points decreased; nanoparticles coated with branched PEG more markedly suppressed cell growth in culture. In the presence of graphene oxide nanoparticles, peripheral blood mononuclear cells retained high viability in culture after daily monitoring in the Cell-IQ system. The studied nanoparticles were engulfed by monocytes and the type of PEGylation had no effect on this process. Thus, graphene oxide nanoparticles reduced the increase in peripheral blood mononuclear cell mass during dynamic observation in the Cell-IQ system without reducing their viability.

In vitro safety assessment of reduced graphene oxide in human monocytes and T cells

Considering the increase in the use of graphene derivatives in different fields, the environmental and human exposure to these materials is likely, and the potential consequences are not fully elucidated. This study is focused on the human immune system, as this plays a key role in the organism's homeostasis. In this sense, the cytotoxicity response of reduced graphene oxide (rGO) was investigated in monocytes (THP-1) and human T cells (Jurkat). A mean effective concentration (EC₅₀-24 h) of 121.45 ± 11.39 μg/mL and 207.51 ± 21.67 μg/mL for cytotoxicity was obtained in THP-1 and Jurkat cells, respectively. rGO decreased THP-1 monocytes differentiation at the highest concentration after 48 h of exposure. Regarding the inflammatory response at genetic level, rGO upregulated IL-6 in THP-1 and all cytokines tested in Jurkat cells after 4 h of exposure. At 24 h, IL-6 upregulation was maintained, and a significant decrease of TNF-α gene expression was observed in THP-1 cells. Moreover, TNF-α, and INF-γ upregulation were maintained in Jurkat cells. With respect to the apoptosis/necrosis, gene expression was not altered in THP-1 cells, but a down regulation of BAX and BCL-2 was observed in Jurkat cells after 4 h of exposure. These genes showed values closer to negative control after 24 h. Finally, rGO did not trigger a significant release of any cytokine at any exposure time assayed. In conclusion, our data contributes to the risk assessment of this material and suggest that rGO has an impact on the immune system whose final consequences should be further investigated.