Toxicity of ZnO/TiO₂‐conjugated carbon‐based nanohybrids on the coastal marine alga Thalassiosira pseudonana

Abstract

Increasing consumption of metal-oxide nanoparticles (NPs) and carbon-based nanomaterials has caused significant concern about their potential hazards in aquatic environments. The release of NPs into aquatic environments could result in adsorption of NPs on microorganisms. While metal-oxide NP-conjugated carbon-based nanohybrids (NHs) may exhibit enhanced toxicity toward microorganisms due to their large surface area and the generation of reactive oxygen species (ROS), there is a lack of information regarding the ecotoxicological effects of NHs on marine diatom algae, which are an indicator of marine pollution. Moreover, there is scant information on toxicity mechanisms of NHs on aquatic organisms. In this study, four NHs (ie, ZnOconjugated graphene oxide [GO], ZnO-conjugated carbon nanotubes [CNTs], TiO 2conjugated GO, and TiO 2 -conjugated CNT) that were synthesized by a hydrothermal method were investigated for their toxicity effects on a Thalassiosira pseudonana marine diatom. The in vitro cellular viability and ROS formation employed at the concentration ranges of 50 and 100 mg/L of NHs over 72 hours revealed that ZnO-GO had the most negative effect on T. pseudonana. The primary mechanism identified was the generation of ROS and GO-induced dispersion that caused electrostatic repulsion, preventing aggregation, and an increase in surface areas of NHs. In contrast to GO-induced dispersion, large aggregates were observed in ZnO/TiO 2conjugated CNT-based NHs. The scanning electron microscopy images suggest that NHs covered algae cells and interacted with them (shading effects); this reduced light availability for photosynthesis. Detailed in vitro toxicity effects and mechanisms that cause high adverse acute toxicity on T. pseudonana were unveiled; this implied concerns about potential hazards of these mechanisms in aquatic ecosystems. K E Y W O R D S carbon nanotube, graphene oxide, metal oxides, nanohybrids, Thalassiosira pseudonana,toxicity

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Applications of metallic nanomaterials for the treatment of water

“…Despite all the developments, nanophotocatalysts still face some problems which include toxicity and recovery of catalysts from mixture (Mahmoodi and Arami 2009). Because of the toxicity of nanomaterials (Baek et al 2020;Boyle et al 2020), there are chances of wide unwanted outcomes. So, there is an urgent need to develop different nanocomposites with reduced toxicity while being used in water treatment processes.…”

“…Because of the toxicity of nanomaterials (Baek et al . 2020; Boyle et al . 2020), there are chances of wide unwanted outcomes.…”

Theoretical investigation of the mechanism of phospholipid extraction from the cell membrane using functionalized graphene quantum dots

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“…Therefore, exploring the interaction between carbon nanomaterials and different organisms can better elucidate the potential toxicity of carbon nanomaterials. 16,17…”