Main results obtained in a series of animal experiments for the assessment of the organism's responses to metallic nanoparticles exposure

Nanoparticles (NPs) of Fe₃O₄ were produced by a chemical technique and NPs of Ag, Au, CuO, NiO, Mn₃O₄, PbO, ZnO, TiO₂, SiO₂, and Al₂O₃ – by laser ablation in water. In some experiments we compared particles of a given chemical composition having different diameters, while in others – equidimensional NPs of different metals or metal oxides (Me-NPs). We used two experimental models: a single intra-tracheal instillation of Me-NPs 24 h before the bronchoalveolar lavage procedure (collecting) and the repeated intra-peritoneal injections during 6-7 weeks in non-lethal doses. Besides, we carried out long-term inhalation experiments with NPs of Fe₂O₃, SiO₂, and NiO. We have demonstrated that NPs are much more noxious than their fine micrometric or even submicron counterparts and are usually the more toxic the smaller their dimensions within the nanoscale range. We have found also that toxicity of Me-NPs strongly depends on their chemical nature, solubility, and specific mechanisms of characteristic action of a given metal in any chemical form. Solubility of Me-NPs in biological milieus plays an important role in their toxicokinetics, which can prevail over that of the physiological mechanisms controlling their distribution, retention, and elimination. On the other hand, thanks to the high activity of these mechanisms, the organism is not defenceless against the impact of Me-NPs. The toxicity and even genotoxicity of Me-NPs can be significantly decreased by adequately composed combinations of some bioactive agents in innocuous doses.