Fate of ZnS:Mn quantum dots in Seine River water and seawater. Ecotoxicological effects on Chlorella Vulgaris microalgae

The release of engineered materials into the environment can have detrimental effects on living organisms in ground, rivers, and oceans. Despite the increasing use of nanomaterials, little research is conducted on their degradation. Understanding the biology and environmental consequences of manufactured materials is crucial for preserving the environment and developing more respectful chemistry protocols. Physicochemical studies are essential to understand material behavior and their uptake and distribution within microorganisms. II-VI semiconducting nanocrystals, like ZnS nanoparticles, have emerged due to their quantum confinement, allowing for customization of electronic and optical properties. To assess the toxicity of ZnS QDs doped with Mn2+ and perform ecotoxicological tests, a suitable natural environment and an aquatic model are needed. Microalgae, like Chlorella Vulgaris, offer advantages in ecotoxicology, including environmental relevance, sensitivity, experimental feasibility, ethical considerations, and comparative studies. This paper presents the synthesis of ZnS:Mn NPs with varying concentrations of Mn2+. These NPs induce an antioxidant defense system in algal cells, which may be toxic to Chlorella vulgaris via an oxidative stress mechanism. The toxicity of manganese-doped ZnS nanoparticles does exist but is lower than that induced by a Mn2+ ion concentration of 100 mg L-1.