Cobalt tungstate nanoparticles (CoWO4 NPs) affect the photosynthetic performance of the green microalga Raphidocelis subcapitata
Abstract: Innovative applications of cobalt tungstate nanoparticles (CoWO4 NPs) are directly linked to their increased production and consumption, which can consequently increase their release into aquatic ecosystems and the exposure of organisms. Microalgae are autotrophic organisms that contribute directly to global primary productivity and provide oxygen for maintaining many organisms on Earth. In this paper, we assessed the toxicity of CoWO4 NPs when in contact with the freshwater microalga Raphidocelis subcapitata (Chlorophyceae). To this end, we assessed algal growth, reactive oxygen species (ROS) production and photosynthetic performance. Our results show that the NPs inhibited the growth of algal cells from 42.37 mg L−1, significantly induced ROS production in the first hours of exposure (1 h) at all concentrations and directly compromised the photosynthetic activity, reinforcing that the oxygen-evolving complex (OEC) is one of the main targets of NPs and that the light curve parameters were the most sensitive endpoints. We observed reductions in the maximum relative electron transport rate (rETRmax) of around 53% and decreases in the saturating irradiance (Ek) of around 40%, which demonstrated that the NPs not only compromised the photosynthetic activity, but also decreased the ability of algal cells to tolerate high light intensities. Our results also highlight that Co was mostly particulate and that the dissolved fraction represented only ∼8% at the lowest concentration and ∼0.70% at the highest concentration of CoWO4 NPs, suggesting that the toxicity observed was caused by the NPs. CoWO4 NPs exhibited a high negative surface charge of −33mV in L.C. Oligo medium. The polydispersity index (PdI) varied from 0.22 to 0.45, while the hydrodynamic size ranged from 217.8 ± 11.36 to 503.43 ± 32.78 nm, indicating greater aggregation in this medium. This study elucidates how the CoWO4 NPs interact with R. subcapitata, resulting in changes mainly in its photosynthetic performance.
Author(s): Cínthia Bruno de Abreu, Renan Castelhano Gebara, Giseli Swerts Rocha, Adrislaine da Silva Mansano, Marcelo Assis, Thalles Maranesi Pereira, Luciano Sindra Virtuoso, Ailton José Moreira, Patrícia Franklin Mayrink Nogueira, Valtencir Zucolotto, Maria da Graça Gama Melão, Elson Longo.
Chemosphere
Volume 372, March 2025, 144085
DOI: https://doi.org/10.1016/j.chemosphere.2025.144085
CDMF
The CDMF, hosted at the Federal University of São Carlos (UFSCar), is one of the Research, Innovation and Dissemination Centers (RIDC) supported by the São Paulo State Research Support Foundation (Fapesp), and also receives investment from the National Council Scientific and Technological Development (CNPq), from the National Institute of Science and Technology of Materials in Nanotechnology (INCTMN).
