Developmental toxicity of Fe 3 O 4 nanoparticles on cysts and three larval stages of Artemia salina.

Using Artemia salina cysts (capsulated and decapsulated) and larvae (instar I, II and III) as experimental models, the potential effects of Fe ₃ O ₄ nanoparticles (Fe ₃ O ₄ -NPs) on marine ecosystems were investigated. Hatchability, mortality and a number of ethological, morphological and biochemical parameters were selected as end-points to define the toxic responses. Data showed that the hatching rates of capsulated and decapsulated cysts were significantly decreased (p < 0.01) following exposure to 600 mg/L for 24 and 36 h. The LC ₅₀ values for instar II and III were 482 and 561 mg/L (could not be measured for instar I), and the EC ₅₀ values for swimming inhibition of instar I, II and III were 474, 365 and 421 mg/L, respectively. Effects on hatchability, mortality and swimming were accounted for Fe ₃ O ₄ -NPs rather than iron ion released from the NPs. Instar II larvae showed the greatest sensitivity to Fe ₃ O ₄ -NPs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Body lengths of instar I, II and III larvae were decreased in dose-dependent manners. Fe ₃ O ₄ -NPs attached onto the gills and body surface, resulting in irreversible damages. Reactive oxygen species, malondialdehyde content, total antioxidant capacity and antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities were substantially increased following exposure, indicating that toxic effects were related to oxidative stress. Mitochondrial malformation, cristae rupturing and membranous structure disruption were clearly observed after Fe ₃ O ₄ -NPs exposure. Fe ₃ O ₄ -NPs were ingested and well distributed in the gut, yolk and primary body cavity. Uptake kinetics data showed that the maximum Fe ₃ O ₄ -NPs content (16.4 mg/g) was reached at 30 h. The combined results so far indicate that Fe ₃ O ₄ -NPs have the potential to affect aquatic organisms when released into the marine ecosystems.
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