Desenvolvimento de filmes de carboximetilcelulose com nanopartículas de prata e avaliação de sua atividade antimicrobiana e toxicidade

Abstract

One alternative for new packagings is the use of renewable materials as raw materialin the development of films, with the challenge of maintaining the quality of the product. Polysaccharides are abundant and renewable origin, and its derivatives, such as carboxymethylcellulose, widely used in the food industry, have potential use as new materials in the form of films. However, there are challenges adequacies of mechanical properties and incorporation of new features (as antimicrobial) in carboxymethylcellulose films to make her suitable for packaging use. A promising system to modify the characteristics of these films is the incorporation of nanostructures. However, in Brazil there is no legislation to nanomaterials and the increased use of this technology, it is important to value the impact of these new materials from development to the final consumer, to better direct the search. In this context, the objective of this study was to develop carboxymethylcellulose films with PVA-silver nanoparticlesand evaluate their antimicrobial activity and toxicity. Silver nanoparticles were synthesized and incorporated in carboxymethylcellulose, via solution, obtaining films by casting. The following techniques to characterize films/solutions were used: spectrophotometry UV-Vis, Analysis of Particle Size, Zeta Potential, Water Vapor Permeability, Infrared Spectrophotometry, Thermal Analysis (Thermogravimetry and Differential Scanning Calorimetry), Mechanical Testing Tensile, Film Solubility in Water, Scanning Electron Microscopy (SEM / FEG) and Colorimetry. Generally, the addition of nanoparticles modified the characteristics of films, increasing mechanical properties at 66.7%. Evaluated the antimicrobial activity of the nanostructured system by Minimum Inhibitory Concentration (MIC) and inhibition zone, using Gram-positive bacteria (Enterococcus faecalis) and Gram-negative (Escherichia coli).MIC values showed the high effectiveness of the incorporation of the nanoparticles of CMC films (0,12^g mL-1), demonstrating the potential of this material for use in antimicrobial packages. In valuation of the toxicity of this nanostructured system, in vivo tests were performed in cultured cells (cyto and genotoxicity in Allium cepa), ingestion in Wistar rats and ecotoxicity in microcrustacean Daphnia similis. In meristematic cells of A. cepa, no result of cytotoxicity was verified in A. cepa. The analysis of chromosomal aberrations indicated predominance of abnormalities such as bridges chromosome in anaphase, verifying a clastogenic action of PVA-silver nanoparticles. Tests with rats have suggested the toxicity of nanostructured system, causing vacuolation in the liver and intestine crypt dilation, with accumulation of PVA-silver nanoparticles in ileum. Results of ecotoxicity have suggested a toxic potential of silver nanoparticles to aquatic invertebrates (CE5024 and 48 h equal to 0,0015 e 0,0012^g mL-1, respectively). The results of this study indicate that, even at low concentrations, PVA-silver nanoparticles can induce cellular damage in exposed organisms. Due to its increasing use, these data reinforce the importance of performing studies with silver nanoparticles as part of nanostructured systems.