Estudo dos efeitos de toxicidade crônica de nanopartículas de prata frente à microalga Desmodesmus subspicatus

Abstract

Currently, nanotechnology is a promising science mostly due to the mechanical, optical, magnetic and chemical properties presented by nanoparticles and nanomaterials. Silver nanoparticles, the focus of this study, have been commercially produced on a large scale due to their properties such as good conductivity, large surface area, and excelente antimicrobial activity that qualifies them for a range of applicability. Despite the encouraging perspectives on the benefits of nanotechnology, nanotoxicology has gained space in the scientific community due to the need to obtain more information, especially regarding the safety of these nanometer scale materials against biological systems. In order to evaluate the possible effects caused by silver nanoparticles to aquatic organisms, toxicological tests were performed, characterized by the exposure of the microalgae Desmodesmus subspicatus, to diferent concentrations of silver nanoparticles, 25, 50, 100, 200 e 400 µg.L −1 , under apecified lighting, aeration and test time conditions. The silver nanoparticles were synthesized and characterized by Transmission Electron Microscopy, Zeta Potencial and UV-Visible Absorption Spectroscopy, presenting a diameter of 4,6 nm and a surface area of 124,2 m².g −1 , spherical morphology, good dispersion and a certain degree of instability. The chronic toxicity tests were performed in triplicate, after statistical analysis of the data obtained, a dose-response curve was reached and allowed to verify the effective concentration of the toxic agent capable of inhibiting 50% of algal biomass growth 𝐸𝐶50,72ℎ de 0,3148 ± 0,096 mg.L −1 . The high toxicity of silver nanoparticles towards aquatic organisms is evidenced, as well as the importance of studies aimed to analyzing th effects caused by chemical substances on biological systems and it is recommended to perform more tests to identify the other effects caused by silver nanoparticles and increase the reliability of the result obtained in this study, since this value cannot be safely compared with other studies due to the particularities that each one presents.