Mechanisms of eco-corona effects on micro(nano)plastics in marine medaka: Insights into translocation, immunity, and energy metabolism.

Biomolecules, prevalent in the marine environment, can readily adsorb onto the surface of micro(nano)plastics (MNPs), forming eco-corona. This study indicated that 50 nm polystyrene nanoplastics (NP50), whether wrapped with eco-corona or not, can passively enter embryos, whereas 5 µm polystyrene microplastics (MP5) cannot. Additionally, translocation of MP5 from the intestine to the liver was observed in larvae, a process facilitated by eco-corona. Notably, eco-corona prolonged the retention time of MNPs in larvae. However, NP50 was more challenging to purify than MP5, irrespective of the presence of eco-corona. Interestingly, eco-corona degraded in the intestine during the uptake of MNPs, and the hard coronae that readily formed on NP50 may restrict the degradation rate. Although NP50 significantly disrupted larval microbiota homeostasis compared with MP5, eco-corona was more likely to exacerbate MP5's damage to the intestine and liver by disrupting microbiota homeostasis. Additionally, NP50 caused more significant damage to immunity and energy metabolism compared with MP5, regardless of the presence of eco-corona. This study revealed that previously overlooked biomolecules in the marine environment can enhance the translocation of MNPs and subsequently exacerbate their toxic effects, providing theoretical support for assessing the ecological risks of MNPs in real environments.