The effect of natural biomolecules on yttrium oxide nanoparticles from a Daphnia magna survival rate perspective.

The attention to rare earth oxide nanoparticles (NPs), including yttrium oxide (Y 2 O 3 ), has increased in many fields due to their unique structural characteristics and functional properties. The aim of our study was to investigate the mechanisms by which bio-corona formation on Y 2 O 3 NPs affects their environmental fate and toxicity. The Y 2 O 3 NPs induced toxicity to freshwater filter feeder Daphnia magna at particle concentrations of 1 and 10 mg/L, regardless of particle size. Interactions between naturally excreted biomolecules (e.g. protein, lipids, and polysaccharides) derived from D. magna, and the Y 2 O 3 NPs (30-45 nm) resulted in the formation of an eco-corona, which reduced their toxic effects toward D. magna at a particle concentration of 10 mg/L. No effects were observed at lower concentrations or for the other particle sizes investigated. Copper-zinc (Cu-Zn) superoxide dismutase, apolipophorins, and vitellogenin-1 proteins proved to be the most prominent proteins of the adsorbed corona, and possibly a reason for the reduced toxicity of the 30-45 nm Y 2 O 3 NPs toward D. magna.