Toxicological effects of nanometer titanium dioxide (nano-TiO2) on Chlamydomonas reinhardtii

• Published in: Ecotoxicology and environmental safety Vol. 84; pp. 155 - 162
• Main Authors: Chen, Lanzhou, Zhou, Lina, Liu, Yongding, Deng, Songqiang, Wu, Hao, Wang, Gaohong
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.10.2012; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; cell growth; cell membranes; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - drug effects; chlorophyll; Chlorophyll - analysis; chloroplasts; Chloroplasts - drug effects; Ecotoxicology, biological effects of pollution; Electron microscopy; Fundamental and applied biological sciences. Psychology; General aspects; image analysis; lipid peroxidation; Lipid Peroxidation - drug effects; malondialdehyde; Malondialdehyde - pharmacology; Microscopy, Electron; Nanometer titanium dioxide; nanoparticles; Nanoparticles - toxicity; photosynthesis; Photosynthesis - drug effects; Physiological responses; plasmolysis; protein synthesis; Titanium - toxicity; titanium dioxide; Toxicological effects; Toxicological effects; Electron microscopy; Physiological responses; Chlamydomonas reinhardtii; Nanometer titanium dioxide; Chlorophyta; Ecotoxicology; Toxicity; Algae; Environment; Chlorophyceae
• ISSN: 0147-6513; 1090-2414; 1090-2414
• DOI: 10.1016/j.ecoenv.2012.07.019

The toxicological effects of nanometer titanium dioxide (nano-TiO2) on a unicellular green alga Chlamydomonas reinhardtii were assessed by investigating the changes of the physiology and cyto-ultrastructure of this species under treatment. We found that nano-TiO2 inhibited photosynthetic efficiency and cell growth, but the content of chlorophyll a content in algae did not change, while carotenoid and chlorophyll b contents increased. Malondialdehyde (MDA) content reached maximum values after 8h exposure and then decreased to a moderately low level at 72h. Electron microscopy images indicated that as concentrations of nano-TiO2 increased, a large number of C. reinhardtii cells were noted to be damaged: the number of chloroplasts declined, various other organelles were degraded, plasmolysis occurred, and TiO2 nanoparticles were found to be located inside cell wall and membrane. It was also noted that cell surface was surrounded by TiO2 particles, which could present an obstacle to the exchange of substances between the cell and its surrounding environment. To sum up, the effect of nano-TiO2 on C. reinhardtii included cell surface aggregation, photosynthesis inhibition, lipid peroxidation and new protein synthesis, while the response of C. reinhardtii to nano-TiO2 was a rapid process which occurs during 24h after exposing and may relate to physiological stress system to mitigate damage. ► The toxicological effects of nano-TiO2 on C.reinhardtii were investigated. ► Nano-TiO2 treatment inhibited Fv/Fm, after which inhibition decreased. ► Micrographs of SEM and TEM showed the damage of cyto-ultrastructure. ► Nano-TiO2 treatment increased soluble protein content. ► The response of C.reinhardtii to Nano-TiO2 was a rapid process.