UV-B radiation enhances the toxicity of TiO₂ nanoparticles to the marine microalga Chlorella pyrenoidosa by disrupting the protection function of extracellular polymeric substances

Abstract

Weakened EPS protection of algal cells contributing to the increased internalization of TiO2 nanoparticles was identified as the key mechanism for the enhanced toxicity of TiO2 nanoparticles under UV-B irradiation.

The comparative effects of visible light and UV-A radiation on the combined toxicity of P25 TiO2 nanoparticles and polystyrene microplastics on Chlorella sp.

“…under UVAR conditions. Another related study(Zhu et al 2022) also noted that the exposure of nTiO 2 under UV-B radiation enhanced ROS production in marine algae Chlorella pyrenoidosa.…”

“…This can be attributed to the extracellular polymeric substance secretion by the algal cells. UV conditions can stimulate the production of EPS that may facilitate the aggregation of algal cells(Xiao and Zheng 2016;Zhu et al 2022). This was validated through FE-SEM images in the current work, which clearly depicts the excessive layer of EPS forming around the algal cells in the test groups exposed under UVAR conditions.…”

“…Similarly,(Thiagarajan et al 2019a) reported that hetero-aggregation of nTiO 2 and NH 2 MPs with marine algae Chlorella sp. resulted in cellular damage.The generation of ROS and the ensuing oxidative stress has long been recognized as a principal mode of action underpinning the toxicity associated with NPs(Zhu et al 2022). These reactive species possess the ability to induce cellular damage, lipid peroxidation, and to impede photosynthesis(Liu et al 2018;Middepogu et al 2018).…”

Ecological risk assessment of metallic nanoparticles on the marine environments: Species sensitivity distributions analysis

“…Nanoscale particles can exhibit special characteristics and high reactivity because of the larger proportion of atoms or molecules and the numbers of reactive groups distributed on their surface (Nel et al, 2006). Therefore, the environmental and health risks of NPs have attracted widespread concerns and some studies have revealed the adverse effects of NPs on marine organisms (Qian et al, 2020;Du et al, 2021;Zhu et al, 2022). It is generally considered that the toxicity of NPs is size-dependent, which means that smaller NPs are more toxic than larger ones.…”

“…Besides, the "Trojan horse" effect maybe also contribute to the toxicity of metallic NPs with the ability to release ions, which means NPs could enter the cell and then start releasing toxic ions (Wang and Wang, 2014;Moreno-Garrido et al, 2015). Although the aggregation of NPs was observed in seawater, which was driven by the high ionic strength, there are still some particles that remain at the nanoscale and exhibit the nano-size effect (Xia et al, 2018;Zhu et al, 2022).…”