Stability and toxicity of differently coated selenium nanoparticles under model environmental exposure settings

This study, motivated to fill the knowledge gap on environmental safety of selenium nanoparticles (SeNPs), provides information on the stability and environmental safety of four differently coated SeNPs rendering both positive and negative surface charges. The stability and dissolution behaviour of SeNPs were determined in an aquatic model media of different ionic strength to provide information regarding the environmental fate of SeNPs in different environmental conditions. The environmental safety of SeNPs was evaluated by acute regulatory toxicity tests using Daphina magna and Vibrio fischeri as model organisms. Agglomeration was observed for all studied SeNPs in test media with higher ionic strength caused by the disruption of surface charge leading to electrostatic instability. Toxicity of SeNPs on both aquatic species was dose-dependent and increased with exposure time. The obtained data indicated that all of the tested SeNPs could be classified as harmful to the natural bacteria V. fischeri and harmful to toxic to crustaceans D. magna, but dependent on the coating agent used for SeNPs stabilization. Although SeNPs have attracted great interest for use in biomedicine, this study demonstrated that their ecotoxicological effects should be considered during the design of new of SeNPs-based products.