Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review.

The increasing use of titanium dioxide nanoparticles (TiO 2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO 2 NPs on both humans and the environment. Notably, TiO 2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO 2 NPs in different species and in vitro models. Following exposure, TiO 2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO 2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO 2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO 2 NPs. However, a systematic comparison of the neurotoxic effects of TiO 2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO 2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO 2 NPs.