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Nanoparticles incorporated in consumer and industrial products cause concerns about their potential ecological impacts. Zinc oxide nanoparticles (ZnO-NP) have several applications, which increases their potential for release to the environment, causing ecotoxicological problems. Bivalve mollusks are susceptible targets for nanoparticles toxicity, since nanomaterials can enter the cells by endocytosis mechanisms. Limnoperma fortunei (golden mussel) are validated for biomonitoring purposes and have a wide distribution in the South of Brazil, where it can be collected throughout the year. The aim of this study was to evaluate the in uence of ZnO-NP on the redox metabolism by enzymatic and non-enzymatic antioxidant defense assessment in addition to DNA damage by DNA fragmentation assay in L. fortunei after exposure to ZnO-NP. Adult bivalves were placed in contact with 1, 10, and 50 µg mL -1 ZnO-NP during three incubation times: 2, 4 and 24 h. Ionic Zn release, enzymatic and non-enzymatic antioxidant activity, oxidative damage to lipids and proteins and DNA damage were evaluated. Oxidative damage to proteins and lipids were observed after 4 h exposure and returned to baseline levels after 24 h. Superoxide dismutase levels decreased after 4 h exposure and increased after 24 h. No signi cant alteration was observed in catalase activity or even DNA double strand cleavage. The dissociation of ZnO may occur after 24 h, releasing ionic zinc (Zn 2+ ) by hydrolysis, which was con rmed as the ionic Zn concentration increased following 24 h exposure. In conclusion, ZnO-NP were able to induce oxidative stress in exposed golden mussels. The golden mussel is capable to modulate its own antioxidant defences in response to oxidative stress and seems to be able to hydrolyse the nanoparticle and consequently release Zn 2+ into the cellular compartment.

Nanoparticles incorporated in consumer and industrial products cause concerns about their potential ecological impacts. Zinc oxide nanoparticles (ZnO-NP) have several applications, which increases their potential for release to the environment, causing ecotoxicological problems. Bivalve mollusks are susceptible targets for nanoparticles toxicity, since nanomaterials can enter the cells by endocytosis mechanisms. Limnoperma fortunei (golden mussel) are validated for biomonitoring purposes and have a wide distribution in the South of Brazil, where it can be collected throughout the year. The aim of this study was to evaluate the influence of ZnO-NP on the redox metabolism by enzymatic and non-enzymatic antioxidant defense assessment in addition to DNA damage by DNA fragmentation assay in L. fortunei after exposure to ZnO-NP. Adult bivalves were placed in contact with 1, 10, and 50 µg mL-1 ZnO-NP during three incubation times: 2, 4 and 24 h. Ionic Zn release, enzymatic and non-enzymatic antioxidant activity, oxidative damage to lipids and proteins and DNA damage were evaluated. Oxidative damage to proteins and lipids were observed after 4 h exposure and returned to baseline levels after 24 h. Superoxide dismutase levels decreased after 4 h exposure and increased after 24 h. No significant alteration was observed in catalase activity or even DNA double strand cleavage. The dissociation of ZnO may occur after 24 h, releasing ionic zinc (Zn2+) by hydrolysis, which was confirmed as the ionic Zn concentration increased following 24 h exposure. In conclusion, ZnO-NP were able to induce oxidative stress in exposed golden mussels. The golden mussel is capable to modulate its own antioxidant defences in response to oxidative stress and seems to be able to hydrolyse the nanoparticle and consequently release Zn2+ into the cellular compartment.