Interaction of nanostructured materials in biological systems: toxicity of silver nanoparticles (AgNPs) and titanium dioxide (TiO2) in lettuce (Lactuca sativa) and Artemia salina

Abstract

In recent years, with the advancement of technology, new products have been produced and introduced into everyday life. These products have nanomaterials in their composition that provide new characteristics according to their purpose and use. Different areas such as engineering, medicine, technology and food already incorporate nanoparticles (NPs) in their composition and the daily use of these products inserts these NPs into the environment. Consequently, NPs accumulate in the environment causing damage to the biota, mainly in organisms at the base of the food chain. The main NPs used in the production of new products are silver nanoparticles (AgNPs) and titanium oxide nanoparticles (TiO2NPs) being of great importance to assess the risks inherent to the disposal of these NPs in the environment. Our research used two models already well described in the literature, a plant model and an animal model. The plant model used was lettuce (Lactuca sativa L) and the animal model used was brine shrimp (Artemia salina), in which parameters such as germination speed index, growth, morphological changes and bioaccumulation for lettuce and rate were evaluated of mortality, morphological damage and cell damage for A. salina. We use AgNPs in our assays at concentrations of 12.5, 25, 50 and 100 ppm. In L. sativa, a toxic effect was observed in the highest concentration of AgNPs used (100 ppm) with lower germination index, smaller root size as a result of the accumulation of NPs in the cell. Furthermore, in this study a model of passage of AgNPs through the outer cell wall was proposed. In A. salina, AgNPs at concentrations of 50 ppm and 100 ppm showed higher toxicity with higher mortality rate, morphological changes and cell damage in nauplii instar I and instar II. In nauplii instar I it is not common to observe NPs toxicity, because at this stage A. salina presents an incomplete digestive tract, making it impossible for the animal to filter NPs. Given the above, emphasis was given to the molting process in the AgNPs absorption process. Using titanium dioxide particles (TiO2) in A. salina, the toxic effect was observed at high concentrations (50 and 100 ppm) only in nauplii instar II. According to our results, high concentrations of NPs pose risks to terrestrial and aquatic organisms according to morphological analysis, NP accumulation and cell damage.