Avaliação toxicogenética de óxido de zinco: análise comparativa de nanopartículas e forma massiva em modelos alternativos

Abstract

Nanotechnology consists of the manipulation and production of materials on a nanometric scale. It is an area of science that has gained prominence and development in recent decades. Due to their small size, nanoparticles have more intense physical and chemical properties when compared to molecules on a macroscopic scale. In particular, Zinc Oxide nanoparticles are used for commercial use due to their antibacterial, nanopesticidal and nanofertilizer characteristics. Its bulk form is also used. The harmful effects of using zinc oxide nanoparticles and their massive form lead to concern about the toxic potential of the molecules for both biological systems and the environment. Nanotoxicology aims to explore the adverse effects of nanomaterials. The objective of the work was the toxicogenetic evaluation of zinc oxide nanoparticles and their massive form in in vitro and in vivo models, making a comparison of the harmfulness of both forms of the same material. The concentrations tested ranged from 0.005 to 50μg/ml. For the in vitro test, with prokaryotic cells, the bacterial reversion test was performed. The test is known as the Ames or Salmonella/microsome test. Its objective is to identify the mutagenic potential of chemical compounds using strains of Salmonella enterica serovar Typhimurium that have mutations that interfere with the biochemical processes of histidine (His-) synthesis. The assays were performed with and without metabolic activation. Strains TA97a, TA98, TA100, TA102, TA104 and TA1535 were used. As a eukaryotic model, cells from the HepG2 cell line (human hepatocarcinoma) were used, the water-soluble tetrazolium salt test (WST-1) was performed and cell viability was observed through mitochondrial damage. In vivo, the Acute Toxicity Test was carried out on Zebrafish Embryos (Danio rerio). The test aims to observe lethality to embryos, as well as morphological and cardiac changes in this model after acute exposure to chemical substances. In in vitro tests, induction of mutagenicity was observed in the Ames Test caused by the two forms of Zinc Oxide tested with and without exogenous metabolism in strains TA98 and TA102. In strain TA100, mutagenicity was observed without exogenous metabolism induced by the bulk form at the highest concentration tested. In the WST-1 analysis, greater cytotoxicity was observed in a dose-dependent manner caused by nanoparticles in the HepG2 lineage when compared to the bulk form, promoting greater mitochondrial damage and reducing cell viability. In the in vivo model, it was observed that the nanoparticles interfered with the anatomical development of the embryos, altering the diameter of the eyes and body size. The heartbeat was not changed. In summary, given the positive results for toxicity, both zinc oxide in bulk and nanoparticle form need to have their applicability reviewed in terms of toxicological safety and ecotoxicity.