Nanomaterials have been widely used in many fields in the last decades, including electronics, biomedicine, cosmetics, food processing, buildings, and aeronautics. The application of these nanomaterials in the medical field could improve diagnosis, treatment, and prevention techniques. Graphene oxide (GO), an oxidized derivative of graphene, is currently used in biotechnology and medicine for cancer treatment, drug delivery, and cellular imaging. Also, GO is characterized by various physicochemical properties, including nanoscale size, high surface area, and electrical charge. However, the toxic effect of GO on living cells and organs is a limiting factor that limits its use in the medical field. Recently, numerous studies have evaluated the biocompatibility and toxicity of GO in vivo and in vitro. In general, the severity of this nanomaterial’s toxic effects varies according to the administration route, the dose to be administered, the method of GO synthesis, and its physicochemical properties. This review brings together studies on the method of synthesis and structure of GO, characterization techniques, and physicochemical properties. Also, we rely on the toxicity of GO in cellular models and biological systems. Moreover, we mention the general mechanism of its toxicity.

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Mitotic activity in the forebrain subventricular zone is well documented but only in vitro reports suggest the presence of multi-potent stem cells all along the adult mammalian neuraxis. We demonstrate, following cerebroventricular infusion of labeled nucleotides in rat brain, a mitotic activity in the choroid plexus, the ependymal and subependymal layers of the mid- and hindbrain. This proliferation, which probably enables renewal of these structures, was unaffected by the destruction of their serotonergic innervations. Nestin, a marker of immature neural cells, was observed in some proliferative subependymal cells, some classical ependymocytes and in the specialized ependymocytes of the subcommissural organ, the collicular recess and the tanycytes. These observations indicate the presence of immature proliferative cells in the third and fourth periventricular structures, which may generate neural cells.

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