Comparative toxicity assessment of individual, binary and ternary mixtures of SiO2, Fe3O4, and ZnO nanoparticles in freshwater microalgae, Scenedesmus obliquus: Exploring the role of dissolved ions

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology 2023-11, Vol.273, p.109718-109718, Article 109718
• Main Authors: Das, Soupam, Giri, Sayani, Jose, Shinta Ann, Pulimi, Mrudula, Anand, Shalini, Chandrasekaran, N., Rai, Pramod Kumar, Mukherjee, Amitava
• Format: Article
• Language: English
• Subjects: Binary and ternary mixture; Freshwater algae; Metal ions toxicity; Metal oxide nanoparticles; Oxidative stress; Photosynthetic efficiency
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2023.109718

Metal oxide nanoparticles (NPs) are considered among the most prevalent engineered nanomaterials. To have a deeper understanding of the mode of action of multiple metal oxide nanoparticles in mixtures, we have used a unicellular freshwater microalga Scenedesmus obliquus as a model organism. The toxicity of silicon dioxide (SiO2), iron oxide (Fe3O4), and zinc oxide (ZnO) NPs was studied individually as well as in their binary (SiO2 + Fe3O4, Fe3O4 + ZnO, and ZnO + SiO2) and ternary (SiO2 + Fe3O4 + ZnO) combinations. The effects of metal ions from ZnO and Fe3O4 were investigated as well. The results observed from the study, showed that a significant amount of toxicity was contributed by the dissolved ions in the mixtures of the nanoparticles. Decreases in the cell viability, ROS generation, lipid peroxidation, antioxidant enzyme activity, and photosynthetic efficiency were analyzed. Among all the individual particles, ZnO NPs showed the maximum effects and increased the toxicities of the binary mixtures. The binary and ternary mixtures of the NPs clearly showed increased toxic effects in comparison with the individual entities. However, the ternary combination had lesser toxic effects than the binary combination of Fe3O4 + ZnO. The decline in cell viability and photosynthetic efficiency were strongly correlated with various oxidative stress biomarkers emphasizing the crucial role of reactive oxygen species in inducing the toxic effects. The findings from this study highlight the importance of evaluating the combinatorial effects of various metal oxide NPs as part of a comprehensive ecotoxicity assessment in freshwater microalgae. [Display omitted] •ZnO showed the highest toxicity both individually as well as in binary mixtures•SiO2 NPs generated the least toxicity in both the individual and binary mixture treated cells•Metal ions released from ZnO and Fe3O4 showed toxicity to Scenedesmus obliquus•Reduction in the cell viability, as well as photosynthetic activity, was observed for all treatments•ROS and MDA generation as well as antioxidant enzyme activity increased for all the treatments