Metallic nanoparticles due to their small size and unique physico-chemical characteristics have found excellent applications in various branches of industry and medicine. Therefore, for many years a growing interest has been observed among the scientific community in the improvement of our understanding of the impact of nanoparticles on the living organisms, especially on humans. Considering the delicate structure of the central nervous systemit is one of the organs most vulnerable to the adverse effects of metallic nanoparticles. For that reason, it is important to identify the modes of exposure and understand the mechanisms of the effect of nanoparticles on neuronal tissue. In this review, an attempt is undertaken to present current knowledge about metallic nanoparticles neurotoxicity based on the selected scientific publications. The route of entry of nanoparticles is described, as well as their distribution, penetration through the cell membrane and the blood-brain barrier. In addition, a study on the neurotoxicity in vitro and in vivo is presented, as well as some of the mechanisms that may be responsible for the negative effects of metallic nanoparticles on the central nervous system. Graphical abstract: This review summarizes the current knowledge on the toxicity of metallic NPs in the brain and central nervous system of the higher vertebrates.

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Silver nanoparticles (AgNPs) are used in many fields of industry and medicine. Despite the well-established antimicrobial activity, AgNPs are foreseen to be used as anticancer drugs due to the unusual feature—inability to induce drug resistance in cancer cells. The aim of the study was to assess biological activity of AgNPs against MDA-MB-436 cells. The cells were derived from triple-negative breast cancer, a type of breast cancer with poor prognosis and is particularly difficult to cure. AgNPs were toxic to MDA-MB-436 cells and the probable mechanism of toxicity was the induction of oxidative stress. These promising effects, giving the opportunity to use AgNPs as an anti-cancer agent should, however, be treated with caution in the light of further results. Namely, the treatment of MDA-MB-436 cells with AgNPs was associated with the increased secretion of several cytokines and chemokines, which were important in breast cancer metastasis. Finally, changes in the actin cytoskeleton of MDA-MB-436 cells under the influence of AgNPs treatment were also observed.

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The fast-growing use of nanomaterials in everyday life raises the question about the safety of their use. Unfortunately, the risks associated with the use of nanoparticles (NPs) have not yet been fully assessed. The majority of studies conducted so far at the molecular and cellular level have focused on a single-type exposure, assuming that NPs act as the only factor. In the natural environment, however, we are likely exposed to a mixture of nanoparticles, whose interactions may modulate their impact on living organisms. This study aimed to evaluate the toxicological effects caused by in vitro exposure of HepG2 cells to AgNPs in combination with AuNPs, CdTe quantum dot (QD) NPs, TiO2NPs, or SiO2NPs. The results showed that the toxicity of nanoparticle binary mixtures depended on the type and ratio of NPs used. In general, the toxicity of binary mixtures of NPs was lower than the sum of toxicities of NPs alone (protective effect).