Biocompatibility of nanomaterials and their immunological properties

Nanomaterials (NMs) have revolutionized multiple aspects of medicine by enabling novel sensing, diagnostic, and therapeutic approaches. Advancements in processing and fabrication have also allowed significant expansion in the applications of the major classes of NMs based on polymer, metal/metal oxide, carbon, liposome, or multi-scale macro-nano bulk materials. Concomitantly, concerns regarding the nanotoxicity and overall biocompatibility of NMs have been raised. These involve putative negative effects on both patients and those subjected to occupational exposure during manufacturing. In this review, we describe the current state of testing of NMs including those that are in clinical use, in clinical trials, or under development. We also discuss the cellular and molecular interactions that dictate their toxicity and biocompatibility. Specifically, we focus on the reciprocal interactions between NMs and host proteins, lipids, and sugars and how these induce responses in immune and other cell types leading to topical and/or systemic effects.

An overview of experiments with lead-containing nanoparticles performed by the Ekaterinburg nanotoxicological research team

Over the past few years, the Ekaterinburg (Russia) interdisciplinary nanotoxicological research team has carried out a series of investigations using different in vivo and in vitro experimental models in order to elucidate the cytotoxicity and organ-systemic and organism-level toxicity of lead-containing nanoparticles (NP) acting separately or in combinations with some other metallic NPs. The authors claim that their many-sided experience in this field is unique and that some of their important results have been obtained for the first time. This paper is an overview of the team's previous publications in different journals. It is suggested to be used as a compact scientific base for assessing health risks associated not only with the production and usage of engineered lead-containing NPs but also with their inevitable by-production as toxic air pollutants in the metallurgy of lead, copper or their alloys and in soldering operations.

Combined Subchronic Toxicity of Aluminum (III), Titanium (IV) and Silicon (IV) Oxide Nanoparticles and Its Alleviation with a Complex of Bioprotectors

Stable suspensions of metal/metalloid oxide nanoparticles (MeO-NPs) obtained by laser ablation of 99.99% pure elemental aluminum, titanium or silicon under a layer of deionized water were used separately, or in three binary combinations, or in a ternary combination to induce subchronic intoxications in rats. To this end, the MeO-NPs were repeatedly injected intraperitoneally (i.p.) 18 times during 6 weeks before measuring a large number of functional, biochemical, morphological and cytological indices for the organism’s status. In many respects, the Al₂O₃-NP was found to be the most toxic species alone and the most dangerous component of the combinations studied. Mathematical modeling with the help of the Response Surface Methodology showed that, as well as in the case of any other binary toxic combinations previously investigated by us, the organism’s response to a simultaneous exposure to any two of the MeO-NP species under study was characterized by a complex interaction between all possible types of combined toxicity (additivity, subadditivity or superadditivity of unidirectional action and different variants of opposite effects) depending on which outcome this type was estimated for and on effect and dose levels. With any third MeO-NP species acting in the background, the type of combined toxicity displayed by the other two remained virtually the same or changed significantly, becoming either more or less unfavorable. Various harmful effects produced by the (Al₂O₃-NP + TiO₂-NP + SiO₂-NP)-combination, including its genotoxicity, were substantially attenuated by giving the rats per os during the entire exposure period a complex of innocuous bioactive substances expected to increase the organism’s antitoxic resistance.

A paradoxical response of the rat organism to long-term inhalation of silica-containing submicron (predominantly nanoscale) particles of a collected industrial aerosol at realistic exposure levels

While engineered SiO₂ nanoparticle toxicity is being widely investigated, mostly on cell lines or in acute animal experiments, the practical importance of as well as the theoretical interest in industrial condensation aerosols with a high SiO₂ particle content seems to be neglected. That is why, to the best of our knowledge, long-term inhalation exposure to nano-SiO₂ has not been undertaken in experimental nanotoxicology studies. To correct this data gap, female white rats were exposed for 3 or 6 months 5 times a week, 4h a day to an aerosol containing predominantly submicron (nanoscale included) particles of amorphous silica at an exposure concentration of 2.6±0.6 or 10.6±2.1mg/m³. This material had been collected from the flue-gas ducts of electric ore smelting furnaces that were producing elemental silicon, subsequently sieved through a<2μm screen and redispersed to feed a computerized "nose only" inhalation system. In an auxiliary experiment using a single-shot intratracheal instillation of these particles, it was shown that they induced a pulmonary cell response comparable with that of a highly cytotoxic and fibrogenic quartz powder, namely DQ12. However, in long-term inhalation tests, the aerosol studied proved to be of very low systemic toxicity and negligible pulmonary fibrogenicity. This paradox may be explained by a low SiO₂ retention in the lungs and other organs due to the relatively high solubility of these nanoparticles. nasal penetration of nanoparticles into the brain as well as their genotoxic action were found in the same experiment, results that make one give a cautious overall assessment of this aerosol as an occupational or environmental hazard.

Subchronic toxicity of copper oxide nanoparticles and its attenuation with the help of a combination of bioprotectors

In the copper metallurgy workplace air is polluted with condensation aerosols, which a significant fraction of is presented by copper oxide particles<100 nm. In the scientific literature, there is a lack of their in vivo toxicity characterization and virtually no attempts of enhancing organism's resistance to their impact. A stable suspension of copper oxide particles with mean (±SD) diameter 20±10 nm was prepared by laser ablation of pure copper in water. It was being injected intraperitoneally to rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week up to 19 injections. In parallel, another group of rats was so injected with the same suspension against the background of oral administration of a "bio-protective complex" (BPC) comprising pectin, a multivitamin-multimineral preparation, some amino acids and fish oil rich in ω-3 PUFA. After the termination of injections, many functional and biochemical indices for the organism's status, as well as pathological changes of liver, spleen, kidneys, and brain microscopic structure were evaluated for signs of toxicity. In the same organs we have measured accumulation of copper while their cells were used for performing the Random Amplification of Polymorphic DNA (RAPD) test for DNA fragmentation. The same features were assessed in control rats infected intraperitoneally with water with or without administration of the BPC. The copper oxide nanoparticles proved adversely bio-active in all respects considered in this study, their active in vivo solubilization in biological fluids playing presumably an important role in both toxicokinetics and toxicodynamics. The BPC proposed and tested by us attenuated systemic and target organs toxicity, as well as genotoxicity of this substance. Judging by experimental data obtained in this investigation, occupational exposures to nano-scale copper oxide particles can present a significant health risk while the further search for its management with the help of innocuous bioprotectors seems to be justified.

Comparative in vivo assessment of some adverse bioeffects of equidimensional gold and silver nanoparticles and the attenuation of nanosilver's effects with a complex of innocuous bioprotectors

Stable suspensions of nanogold (NG) and nanosilver (NS) with mean particle diameter 50 and 49 nm, respectively, were prepared by laser ablation of metals in water. To assess rat’s pulmonary phagocytosis response to a single intratracheal instillation of these suspensions, we used optical, transmission electron, and semi-contact atomic force microscopy. NG and NS were also repeatedly injected intraperitoneally into rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week, up to 20 injections. A group of rats was thus injected with NS after oral administration of a “bioprotective complex” (BPC) comprised of pectin, multivitamins, some amino acids, calcium, selenium, and omega-3 PUFA. After the termination of the injections, many functional and biochemical indices and histopathological features of the spleen, kidneys and liver were evaluated for signs of toxicity, and accumulation of NG or NS in these organs was measured. From the same rats, we obtained cell suspensions of different tissues for performing the RAPD test. It was demonstrated that, although both nanometals were adversely bioactive in all respects considered in this study, NS was more noxious as compared with NG, and that the BPC tested by us attenuated both the toxicity and genotoxicity of NS.