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ZnO nanoparticles: synthesis, characterization, and ecotoxicological studies.
Roberta Brayner1, Si Amar Dahoumane, Claude Yéprémian
1Universite Paris Diderot (Paris 7), CNRS, UMR 7086, Interfaces, Traitements, Organisation et Dynamique des Systemes, 15 rue Jean de Baif, F-75205 Paris Cedex 13, France. roberta.brayner@univ-paris-diderot.fr
Zinc oxide (ZnO) nanoparticles exhibit varying ecotoxicity towards cyanobacteria and microalgae. Protective agents influence ZnO nanoparticle interactions, affecting photosynthetic activity and cell viability in aquatic microorganisms.
Area of Science:
- Environmental Science
- Ecotoxicology
- Nanotechnology
Background:
- Nanosized zinc oxide (ZnO) synthesis via the polyol process yields particles with varying properties.
- The ecotoxicity of ZnO nanoparticles (ZnO NPs) is a growing concern for aquatic ecosystems.
- Protective agents like tri-n-octylphosphine oxide (TOPO) and polyoxyethylene stearyl ether (Brij-76) can modify NP characteristics.
Purpose of the Study:
- To investigate the ecotoxicity of polyol-synthesized ZnO NPs on Anabaena flos-aquae and Euglena gracilis.
- To assess the influence of protective agents (TOPO, Brij-76) on ZnO NP ecotoxicity.
- To elucidate the mechanisms of ZnO NP interaction and internalization by these microorganisms.
Main Methods:
- Exposure of Anabaena flos-aquae and Euglena gracilis to ZnO, ZnO-TOPO, and ZnO-Brij-76 nanoparticles.
- Measurement of photosynthetic activity as an indicator of ecotoxicity.
- Transmission electron microscopy (TEM) to analyze nanoparticle internalization and cellular effects.
Main Results:
- ZnO NPs induced stress and decreased photosynthetic activity in Anabaena flos-aquae, leading to cell death with ZnO-TOPO.
- Anabaena flos-aquae exposed to ZnO and ZnO-Brij-76 showed recovery of photosynthetic activity after 10 days.
- Euglena gracilis exhibited cell death upon exposure to all tested ZnO NP formulations.
- Anabaena flos-aquae produced polysaccharides that inhibited internalization of ZnO and ZnO-Brij-76 NPs.
- Nanoparticle internalization occurred in Euglena gracilis with all NPs and in Anabaena flos-aquae with ZnO-TOPO NPs.
Conclusions:
- The ecotoxicity of ZnO NPs is dependent on the microorganism and the presence of surface modifiers.
- Surface properties, influenced by agents like TOPO and Brij-76, significantly alter ZnO NP bioavailability and toxicity.
- Cellular defense mechanisms, such as polysaccharide production, play a role in mitigating NP toxicity in certain species.
