Evaluation of alpha and gamma aluminum oxide nanoparticle accumulation,toxicity, and depuration in Artemia salina larvae

In this study, Artemia salina (crustacean filter feeders) larvae were used as a test model to investigate the toxicity of aluminum oxide nanoparticles (Al₂O₃ NPs) on marine microorganisms. The uptake, toxicity, and elimination of α‐Al₂O₃ (50 nm and 3.5 μm) and γ‐Al₂O₃ (5 nm and 0.4 μm) NPs were studied. Twenty‐four and ninety‐six hour exposures of different concentrations of Al₂O₃ NPs to Artemia larvae were conducted in a seawater medium. When suspended in water, Al₂O₃ NPs aggregated substantially with the sizes ranging from 6.3 nm to >0.3 µm for spherical NPs and from 250 to 756 nm for rod‐shaped NPs. The phase contrast microscope images showed that NPs deposited inside the guts as aggregates. Inductively coupled plasma mass spectrometry analysis showed that large particles (3.5 μm α‐Al₂O₃) were not taken up by Artemia, whereas fine NPs (0.4 μm γ‐Al₂O₃) and ultra‐fine NPs (5 nm γ‐Al₂O₃ and 50 nm α‐Al₂O₃) accumulated substantially. Differences in toxicity were detected as changing with NP size and morphology. The malondialdehyde levels indicated that smaller γ‐Al₂O₃ (5 nm) NPs were more toxic than larger γ‐Al₂O₃ (0.4 µm) particulates in 96 h. The highest mortality was measured as 34% in 96 h for γ‐Al₂O₃ NPs (5 nm) at 100 mg/L (LC₅₀ > 100 mg/L). γ‐Al₂O₃ NPs were more toxic than α‐Al₂O₃ NPs at all conditions. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 109–118, 2015.