Surface Characteristics, Copper Release, and Toxicity of Nano‐ and Micrometer‐Sized Copper and Copper(II) Oxide Particles: A Cross‐Disciplinary Study

Abstract

An interdisciplinary and multianalytical research effort is undertaken to assess the toxic aspects of thoroughly characterized nano- and micrometer-sized particles of oxidized metallic copper and copper(II) oxide in contact with cultivated lung cells, as well as copper release in relevant media. All particles, except micrometer-sized Cu, release more copper in serum-containing cell medium (supplemented Dulbecco's minimal essential medium) compared to identical exposures in phosphate-buffered saline. Sonication of particles for dispersion prior to exposure has a large effect on the initial copper release from Cu nanoparticles. A clear size-dependent effect is observed from both a copper release and a toxicity perspective. In agreement with greater released amounts of copper per quantity of particles from the nanometer-sized particles compared to the micrometer-sized particles, the nanometer particles cause a higher degree of DNA damage (single-strand breaks) and cause a significantly higher percentage of cell death compared to cytotoxicity induced by micrometer-sized particles. Cytotoxic effects related to the released copper fraction are found to be significantly lower than the effects related to particles. No DNA damage is induced by the released copper fraction.

Developmental effects of two different copper oxide nanomaterials in sea urchin (Lytechinus pictus) embryos

“…Here, we have demonstrated that synthesized nano-CuO has a higher solubility than commercial nano-CuO (2.5% versus 0.74%, Table 1), probably due to differences in size and purity. The size of synthesized nano-CuO is $10 nm while commercial nanoCuO is between 30 and 100 nm (Table 1 and Figure S1), and it has been demonstrated that small nanoparticles have higher dissolution rates than large particles (Midander et al, 2009). On the other hand, the presence of impurities in the commercial nanoCuO may lower its dissolution rate in a similar way as iron doping decreases the solubility of zinc oxide nanoparticles (nano-ZnO) and leads to a lower toxicity than non-doped nano-ZnO Xia et al, 2011).…”

Chemical Synthesis of Copper Nanospheres and Nanocubes and Their Antibacterial Activity Against Escherichia coli and Enterococcus sp.

“…CuNPs target the cell membrane causing a rapid loss of its integrity, which then leads to cell death. Conversely, CuONPs appear endocytosed within cells in the first hours of interaction which is followed by DNA damage [11].…”

Fluoromica nanoparticle cytotoxicity in macrophages decreases with size and extent of uptake

“…These findings are in contrast to studies of other nano-sized particles where increased toxicity has been associated with a decrease in size. 5,9,12,34,35 Generally, the higher surface area is cited as the likely cause of increasing toxicity. A major difference between many of the nanoparticles previously studied and the fluoromicas is their aspect ratio.…”