Toxicity of Titanium Dioxide Nanoparticles in Central Nervous System and the Molecular Mechanisms Involved

Titanium dioxide nanoparticles(TiO₂ NPs) possess unique characteristics and have found many practical applications in industry and daily life. A wide use of TiO₂ NPs raises the question about their safety to the environment, humans and biota. Once exposed to TiO₂ NPs, they could be absorbed and easily enter the body, cross blood-brain barrier and then accumulated in the brain regions, especially in the cortex and hippocampus, leading to dysfunctions of central nerve system. In vivo and in vitro studies have demonstrated that the morphology and function of glial or neuronal cells could be damaged by TiO₂ NPs. It is summarized the previous studies that the neurotoxic mechanisms mainly consist of oxidative stress, inflammation, apoptosis, genotoxicity, and autophagy. Meanwhile, other factors such as disrupted signaling pathways, depleted neurotransmitters and direct impaired cell components have also been seen in neurotoxicity of TiO₂ NPs. In short, this review aims at understanding the potential neural risks of TiO₂ NPs fully and improving its bio-safety for applications in the near future.