Cytotoxicity of copper- and zinc-containing nanoparticles as health risk factor upon isolated and combined exposure in vivo: Comparative assessmen

Provision of healthy and active longevity is among the most significant trends in the scientific and technical development of the Russian Federation. In this respect, it is highly relevant to perform hygienic assessment of health hazards posed by new materials, nano-sized ones included. At present, materials containing zinc and copper nanoparticles (NPs) are being used more and more widely; this goes for both an alloy (Cu-Zn) or using their oxides separately (CuO, ZnO). This results in exposure involving human health risks. Preliminary assessment revealed high potential hazard posed by Cu-Zn NPs due to, among other things, modified cytotoxicity relative to microparticles (MPs) of its chemical analogue because of the nano-sized phase as well as relative to isolated NPs, which is associated with interaction between the two elements upon combined administration into the body. This necessitates investigations with their focus on comparative assessment and analysis of modified cytotoxicity of the Cu-Zn NPs alloy relative to MPs and isolated NPs in vivo.

The study was performed on Wistar rats involving one-time intratracheal exposure to suspensions in the volume of 0.4 cm3, containing Cu-Zn, CuO, ZnO NPs or Cu-Zn MPs in the concentration of 0.013 g/cm3. Cytotoxicity was comparatively assessed 24 hours after the exposure per changes in the cell population in the bronchoalveolar lavage (BAL).

Verification of physical properties confirmed that the tested materials contained NPs. Cu-Zn NPs differed from MPs per their size, specific surface area and total pore volume (up to 2118 times). Cytotoxic effects produced by isolated CuO and ZnO NPs were identified by growing levels of alveolar macrophages (1.9 times higher against the control); declining levels of neutrophil leukocytes, monocytes, lymphocytes and neutrophil to macrophage ratio (up to 3.5 times). Cu-Zn alloy NPs are more cytotoxic relative to MPs (up to 6.1 times) and isolated NPs (up to 29 times) as established per growing levels of neutrophil leukocytes and neutrophil to macrophage ratio and per declining levels of alveolar macrophages, monocytes, and lymphocytes.

Therefore, the study confirms serious health hazard posed by copper- and zinc-containing NPs, which is manifested, among other things, as cytotoxic effects upon intratracheal exposure in vivo. Cytotoxic effects become stronger upon exposure to Cu-Zn alloy NPs relative to MPs due to the nano-sized phase and relative to isolated NPs due to synergy between the two elements. These findings enrich hygienic concepts about cytotoxicity of copper- and zinc-containing NPs upon isolated and combined exposure in vivo, which makes it possible to provide more effective scientific substantiation for preventive measures and mitigating health risks for exposed population.