Postgraduate Program in Ecology and Natural Resources, Physiological Sciences Department, Federal University of São Carlos, Rod. Washington Luiz Km 235, 13565-905, São Carlos, São Paulo, Brazil; Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, Brazil.
Institute of Physics of São Carlos, University of São Paulo, Av. Trabalhador São-Carlense, 400, 13566-970, São Carlos, São Paulo, Brazil.
Aquat Toxicol. 2023 Sep;262:106640. doi: 10.1016/j.aquatox.2023.106640. Epub 2023 Jul 24.
Graphene oxide (GO) and reduced graphene oxide (rGO) are both widely applicable and there is a massive production throughout the world which imply in inevitable contamination in the aquatic environment by their wastes. Nevertheless, information about their interaction at the cellular level in fish is still scarce. We investigated the metabolic activity, reactive oxygen species (ROS) production, responses of antioxidant defenses, and total antioxidant capacity (TAC) as well as oxidative stress and DNA integrity in zebrafish liver cells (ZFL) exposed to (0.001, 0.01, 0.1 and 1 µg mL) of GO and rGO after two exposure period (24 and 72 h). Higher ROS production and no significant changes in the antioxidant defenses resulted in lipid peroxidation in cells exposed to rGO. Cells exposed to GO increased the activity of antioxidant defenses sustaining the TAC and avoiding lipid peroxidation. Comet assay showed that both, GO and rGO, caused DNA strand breaks after 24 h of exposure; however, only rGO caused DNA damage after 72 h of exposure. The exposure to rGO was significantly more harmful to ZFL cells than GO, even at very low concentrations. The cells showed a high capacity to neutralize ROS induced by GO preventing genotoxic effects and metabolic activity, thus sustaining cell viability. The time of exposure had different impacts for both nanomaterials, GO caused more changes in 24 h showing recovery after 72 h, while cells exposed to rGO were jeopardized at both exposure times. These results indicate that the reduction of GO by removal of the oxygen functional groups (rGO) increased toxicity leading to adverse effects in the cells, even at very low concentrations.
氧化石墨烯（GO）和还原氧化石墨烯（rGO）都具有广泛的应用，并且全球都在大量生产，这意味着它们的废物不可避免地会污染水环境。然而，关于它们在鱼类细胞水平上相互作用的信息仍然很少。我们研究了代谢活性、活性氧（ROS）产生、抗氧化防御反应以及总抗氧化能力（TAC），以及暴露于氧化石墨烯（GO）和还原氧化石墨烯（rGO）后 24 和 72 小时斑马鱼肝细胞（ZFL）的氧化应激和 DNA 完整性。在暴露于 rGO 后，细胞内 ROS 产生增加，抗氧化防御无明显变化，导致脂质过氧化。暴露于 GO 的细胞增加了抗氧化防御的活性，维持了 TAC 并避免了脂质过氧化。彗星试验表明，GO 和 rGO 在暴露 24 小时后均引起 DNA 链断裂；然而，只有 rGO 在暴露 72 小时后引起 DNA 损伤。与 GO 相比，rGO 对 ZFL 细胞的毒性更大，即使在非常低的浓度下也是如此。细胞表现出很高的中和由 GO 诱导的 ROS 的能力，防止了遗传毒性作用和代谢活性，从而维持了细胞活力。暴露时间对两种纳米材料都有不同的影响，GO 在 24 小时内引起了更多的变化，在 72 小时后恢复，而暴露于 rGO 的细胞在两个暴露时间都受到了威胁。这些结果表明，通过去除含氧官能团来还原 GO（rGO）增加了毒性，导致细胞产生不良反应，即使在非常低的浓度下也是如此。
