NanoTiO2 materials mitigate mercury uptake and effects on green alga Chlamydomonas reinhardtii in mixture exposure

Metabolic alterations in alga Chlamydomonas reinhardtii exposed to nTiO2 materials

“…Increasing nTiO 2 concentration resulted in a significant decrease in the absolute values of the zeta potential for the three tested nTiO 2 materials, which was consistent with formation of bigger nTiO 2 aggregates. As shown in our preceding studies, the three nTiO 2 materials form rapidly micrometer aggregates in the exposure medium (2h exposure, 21 ) and the size of the aggregates stayed stable over time interval 24-96h 43 .…”

“…The primary characteristics of the materials as provided by the manufacturer are given in the Table S1, Supplementary information (SI). Stock suspensions of 2.0 gL -1 nTiO 2 were prepared by dispersing nanoparticles in ultrapure water (Millipore, Darmstadt, Germany) using sonication for 10 min ( 50 NH 4 NO 3 with a pH of 7.0± 0.2 and an ionic strength of 2.75 mM, as in our previous studies 21,43 . The selected test concentrations of nTiO 2 are much higher than those found in freshwater environment 3 , but cover a range of ecotoxicologically relevant concentrations 44 .…”

“…The primary threshold was set to 20,000 events on FSC-H. Information on algal cell densities and chlorophyll fluorescence (in FL3) were obtained in a single run after 72 h incubation. Algal cells were discriminated from nTiO 2 aggregates with similar size by applying a gating strategy, as described in our earlier study 21 . The ROS generation and membrane damage were examined using the fluorescent probes CellROX® green (Life Technologies Europe B.V., Zug, Switzerland) and propidium iodide (PI) (Sigma-Aldrich, Buchs, Switzerland) and the number of affected cells was followed by FCM.…”

“…The ROS generation and membrane damage were examined using the fluorescent probes CellROX® green (Life Technologies Europe B.V., Zug, Switzerland) and propidium iodide (PI) (Sigma-Aldrich, Buchs, Switzerland) and the number of affected cells was followed by FCM. The detailed staining procedures and gating strategies are presented in our previous studies 21,46 . The photosynthetic activity of C. reinhardtii was determined prior and after nTiO 2 treatment using a Multiple Excitation Wavelength Chlorophyll Fluorescence Analyzer (Multi-Color-PAM, Walz, Germany).…”

A density gradient centrifugation method for rapid separation of nanoTiO2 and TiO2 aggregates from microalgal cells in complex mixtures with mercury

“…NanoTiO 2 is known to adsorb the dissolved contaminants [3 , 4 , 13] . Our previous work found that inorganic Hg (IHg) could significantly adsorbed to the nanoTiO 2 materials within 2 h [8] . Determining the bioaccumulation potential of the contaminants coexisting with ENMs is an important component of the hazard assessment of chemical mixtures.…”