Toxicity assessment of TiO2-conjugated Carbon-based nanohybrid material on a freshwater bioindicator cladoceran, Daphnia magna

Terrence S Malatjie; Tarryn L Botha; Memory Tekere; Alex T Kuvarega; Thabo T I Nkambule; Bhekie B Mamba; Titus A M Msagati

doi:10.1016/j.aquatox.2022.106176

Toxicity assessment of TiO₂-conjugated Carbon-based nanohybrid material on a freshwater bioindicator cladoceran, Daphnia magna

Aquat Toxicol. 2022 Jun:247:106176. doi: 10.1016/j.aquatox.2022.106176. Epub 2022 Apr 19.

Authors

Terrence S Malatjie¹, Tarryn L Botha², Memory Tekere³, Alex T Kuvarega², Thabo T I Nkambule², Bhekie B Mamba², Titus A M Msagati⁴

Affiliations

¹ Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, P/Bag X6, Roodepoort 1709, South Africa. Electronic address: terrence.cija@gmail.com.
² Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, P/Bag X6, Roodepoort 1709, South Africa.
³ Department of Environmental Sciences, College of Agriculture & Environmental Sciences, University of South Africa, Florida Science Campus, P/Bag X6, Roodepoort 1709, South Africa.
⁴ Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, P/Bag X6, Roodepoort 1709, South Africa. Electronic address: msagatam@unisa.ac.za.

PMID: 35487150
DOI: 10.1016/j.aquatox.2022.106176

Abstract

The application of nanocomposite materials fabricated from titanium dioxide nanoparticles (TiO₂ NPs) and different carbon (C) allotropes have gained popularity in water treatment applications due to their synergistic properties. Studies to date have focused on simple forms of nanomaterials (NMs), however, with the technology development, there is a dramatic increase in production and application of these complex NMs which could result in toxicological impacts on organisms when released into aquatic environments. This raises serious concerns about their safety and the need to ascertain their potential adverse effects on aquatic organisms. While conjugated TiO₂ NPs/carbon-based nanohybrids (TiO₂/C-NHs) may exhibit enhanced photocatalytic activity, there is no research in the scientific community regarding their toxicological effects on D. magna, which are indicators of freshwater pollution. In this study, two under-represented TiO₂/C-NHs (i.e., TiO₂- conjugated carbon nanofiber (CNF), and TiO₂-conjugated multi-walled carbon nanotube (CNT)) were investigated for their toxic effects on D. magna, through a series of acute toxicity tests with a set of sublethal biochemical biomarkers of oxidative stress. The lethal toxicity and oxidative stress formation of TiO₂/C-NHs over 48 h revealed a concentration-dependant increase in D. magna mortality. The primary mechanism identified was the generation of ROS, which was in line with toxicity results. Light microscopy and CytoViva® images visualized D. magna interaction with the NPs, which accumulated and appeared as dark materials in the lines of the gut tract. The collective results indicate that TiO₂/C-NHs have the potential to cause an effect on freshwater organisms when released into the environment. However, the relevance of TiO₂/C-NHs effects needs further chronic toxicity studies since they show promise to be used in nano-bioremediation materials to treat wastewaters.

Keywords: Carbon nanoparticles; CytoViva®; Daphnia magna; Nanocomposites; Nanotoxicity; TiO(2).

MeSH terms

Animals
Aquatic Organisms
Daphnia
Environmental Biomarkers
Fresh Water
Nanoparticles* / chemistry
Nanoparticles* / toxicity
Titanium / chemistry
Water Pollutants, Chemical* / toxicity

Substances

Environmental Biomarkers
Water Pollutants, Chemical
titanium dioxide
Titanium