Avaliação ecotoxicológica de nanopartículas de quitosana obtidas de resíduos agroindustriais para aplicação agrícola sustentável

Abstract

The growing demand for food has driven the development of more sustainable biotechnologies for agriculture, including the use of agroindustrial waste in the production of bioinputs. In this context, chitosan nanoparticles, obtained through the chemical deacetylation of chitin extracted from shrimp waste by lactic fermentation of molasses, followed by the ionic gelation of chitosan, stand out as a promising alternative. However, their ecotoxicological effects are still poorly understood. Therefore, this study aimed to evaluate the ecotoxicological and toxicogenetic effects of these nanoparticles, at concentrations of 0.05%, 0.10%, 0.15%, 0.20%, and 0.30%, in different biological systems. In Chapter 1, the physicochemical characterization of the chitosan nanoparticles was performed, and their cytotoxic, genotoxic, mutagenic, and biochemical effects were investigated in Allium cepa. In Chapter 2, phytotoxic effects were evaluated in Lactuca sativa, and chronic toxicity was assessed in soil organisms using Folsomia candida as a bioindicator. The nanoparticles showed an average size of 196 ± 75 nm and good colloidal stability. In A. cepa, a reduction in the mitotic index and genotoxic damage were observed at the highest concentrations, without induction of mutagenicity, in addition to increased activity of antioxidant enzymes, such as superoxide dismutase, peroxidase, and phenylalanine ammonia-lyase, indicating oxidative stress and plant resistance. In L. sativa, there was no effect on germination; however, the highest concentrations reduced root growth, with the 0.30% concentration being classified as moderately toxic based on the germination index. In F. candida, survival was less affected than reproduction, with the latter being reduced at all tested concentrations. Overall, the results demonstrate concentration-dependent effects, with impacts at the cellular, physiological, and ecological levels. Although chitosan nanoparticles show potential for agricultural applications, especially at low concentrations such as 0.05%, their use requires careful evaluation regarding potential environmental risks.