Effects of three nanomaterials on growth, photosynthetic characteristics and production of reactive oxygen species of diatom Nitzschia Palea

Harmful effect of nanomaterials on aquatic organisms has accelerated in recent decades due to the growth emission of nanomaterials into water. In the present study, we analysed the toxic effects of TiO2, ZnO and MWCTN on diatoms Nitzschia palea in both individual and a combined way. After a short-term (96 h) exposure, the changes of cell density, chlorophyll a, MDA, SOD, CAT, total protein content and morphological structure were determined. Our results showed that: (1) The growth of N. palea was inhibited with the increase of concentration of nanomaterials; (2) The chlorophyll a content of N. palea was sensitive to these three individual nanomaterials; (3) Low concentration of nanomaterials promoted the MDA content in N. palea, but high concentration inhibited it; (4) The protein content of N. palea increased first and then decreased, indicating that nanomaterial stress inhibited diatom protein synthesis and showed dose-effect relationship; (5) After nanomaterial exposure, the SOD enzyme activity of N. palea was significantly inhibited, the CAT enzyme activity showed significantly decreased after exposure, comparing with control. The results of this study provide data for the study of algae nano-toxicology and provide a theoretical basis for the study of the toxicity of nanomaterials to freshwater microalgae.

Automated summary

The harmful effects of nanomaterials on aquatic organisms have been increasing as a result of their release into water. This study investigated the toxic effects of TiO2, ZnO, and MWCTN on the diatom Nitzschia palea, both individually and in combination. The results revealed that the growth of N. palea was inhibited by increasing concentrations of nanomaterials, and the chlorophyll a content of N. palea was sensitive to all three nanomaterials. Furthermore, low concentrations of nanomaterials promoted the production of MDA in N. palea, while high concentrations inhibited it. The protein content of N. palea initially increased and then decreased, suggesting that nanomaterial stress inhibited diatom protein synthesis in a dose-dependent manner. In addition, exposure to nanomaterials significantly suppressed the activity of SOD and CAT enzymes in N. palea. These findings contribute to the understanding of algae nanotoxicology and provide a theoretical basis for studying the toxicity of nanomaterials to freshwater microalgae.