Evaluation of the cytotoxic potential of graphene nanomaterials

• Autor(a) principal: Roxo, Carolina Sofia Pereira
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/22002
• topic: Grafeno; Citotoxicidade; Apoptose; Citometria de fluxo

Graphene is a single-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms and since its isolation, its properties have been widely studied, and graphene and graphene-based nanomaterials are now applied in several fields. Several types of graphene-family nanomaterials (GFN) have been synthesized and widely applied, but there is still some misunderstanding about their potential effects on human health, especially since these nanomaterials can be easily inhaled, especially in the manufacturing process, if they are not properly cared for. In this work, a set of graphene family compounds were selected for the evaluation of their cytotoxic effects on RAW264.7 macrophages. The well-characterized Carbon black nanomaterial was used as reference. Cells were exposed to the BMD30 and 0.5 BMD30 doses defined in previous studies. The internalization of the different GFNs (graphene-family nanomaterials) compounds by RAW264.7 cells was evaluated, as well as its potential oxidative effects by the evaluation of the production of reactive oxygen species (ROS). The GFNs P4, P5 and P6 were selected for further studies due to their highest toxicity potential. The mechanisms of GFNs induced cell death were studied for P4, P5 and P6 by the evaluation of the percentage of cells under apoptosis/necrosis and the mitochondrial membrane potential. The results showed that all the GFNs tested were internalized by RAW 264.7 cells, but P3, P4 and P5 (carboxyl graphene, graphene nanoplatelets and single layer graphene oxide, respectively) were internalized at higher ratios. For P1, P2, P3, P5 and P6 an increase in nanomaterial internalization with exposure duration was observed. Furthermore, the GFNs P2, P3, P4, P6, and P8 showed an increase of ROS production at 0.5BMD30 but not at BMD30 concentrations. The results showed that P4 and P5 increased the number of apoptotic cells and decreased mitochondrial membrane potential of RAW 264.7 cells. Overall our results demonstrate that the toxicity of GFNs is widely dependent on their physico-chemical characteristics, suggesting that from all the GFNs studied, P4 and P5 (graphene nanoplatelets and single layer graphene oxide powder, respectively) were the most cytotoxic to RAW264.7 cells.