Atividade antimicrobiana em filmes poliméricos com diferentes concentrações de nanopartículas de prata
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2018-07-04
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Universidade Estadual Paulista (Unesp)
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Objetivo: Este estudo visou verificar a eficácia antimicrobiana de filmes de polietileno de baixa densidade (PEBD) aditivados com nanopartículas de prata (NPsAg) dispersas no carregador de sílica (SiO2), em diferentes concentrações de partes por milhão (ppm) por filme polimérico. Metodologia: Na pesquisa foram estudadas seis concentrações diferentes de NPsAg (ppm) (1,50; 3,75; 7,50; 15,00; 30,00; 60,00 e 75,00) nos filmes nanoestruturados, sendo estes caracterizados por: Microscopia Eletrônica de Varredura (MEV), Calorimetria Diferencial de Varredura (DSC), Termogravimetria (TGA), Espectroscopia no Infravermelho com Transformada de Foutier (FTIR) e por Difração de Raio X (DRX). A ação antimicrobiana foi pesquisada contra os seguintes microrganismos, Gram Positivos: Staphylococcus aureus, Enterococcus faecalis; Gram Negativos: Escherichia coli e Salmonella typhimurium e o fungo Penicillium expansumi; por meio das metodologias de atividade antimicrobiana por contato, teste por agitação de frascos e Imagens Bacterianas por Microscopia Eletrônica de Varredura. Resultados: A adição de NPsAg na matriz do PEBD não interferiu nas propriedades físico-químicas e térmicas dos filmes. Pelas análises microbiológicas foi observado, pela atividade antimicrobiana por contato, que os filmes nanoestruturados foram eficazes na inibição de todos os microrganismos estudados, sendo que apresentaram uma maior ação antimicrobiana sobre as bactérias Gram negativas e fungos do que as bactérias Gram positivas. Pelo teste de agitação em frascos foi verificado que os filmes nanoestruturados auxiliaram na redução da taxa de crescimento e na concentração máxima na fase estacionária com aumento da duração da fase lag, verificando-se que quanto maior a adição de NPsAg nos filmes, mais eficaz a inibição (p≤0,05). Na Microscopia Eletrônica de Varredura foi observado que as bactérias em contato com NPsAg apresentaram alteração na estrutura da parede microbiana. Conclusão: Os filmes nanoestruturados apresentaram ação antimicrobiana promissora com os microrganismos estudados, portanto, filmes com nanopartículas de prata possuem potencial de uso em embalagens alimentícias, auxiliando na redução de casos de doenças transmitidas por alimentos além de contribuir na redução do desperdício de alimentos.
Objective: this study aims to verify the effectiveness of antimicrobial low density polyethylene films (LDPE), with dispersed silver nanoparticles (AgNPs) added in a silicon carrier, in different concentrations of parts per million (ppm) for each polymeric film. Methodology: In this research, six different concentrations of AgNPs (ppm) were studied (1,50; 3,75; 7,50; 15,00; 30,00; 60,00 e 75,00) in nanostructured films, which were characterized by: Field-Emission Gun Scanning Electron Microscopy (FEG - SEM), Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD). The antimicrobial action was tested against different microorganisms, Gram-positives: Staphylococcus aureus and Enterococcus faecalis, and Gram-negatives: Escherichia coli, Salmonella typhimurium and the fungus Penicillium expansumi. Methodologies employed were antimicrobial activities by contact, shake flasks tests and bacterial images by electronic scanning microscopy (ESM). Results: the addition of AgNPs in the matrix of LDPE did not interfere in the physicochemical and the thermal properties of the films. The analysis of antimicrobial activities by contact showed that the nanostructured films were effective in the inhibition of all the studied microorganisms, with greater action on Gram-negative bacteria and fungi than on Gram-positive bacteria. By the shake flasks test it was verified that the nanostructured films help to reduce growth rate and maximum concentration, with increasing in lag stage duration and observing that the bigger the addition of AgNPs, more effective the inhibiting action (p ≤ 0,05). In electronic scanning microscopy (ESM) it was observed that bacteria in contact with AgNPs presented change in microbial wall struture. Conclusion: the nanostructured films presented a promising antimicrobial action with the studied microorganisms. Hence, silver nanoparticles films have a potential use in food packing, helping to reduce cases of food-borne diseases and contributing to reductions in food waste.
Objective: this study aims to verify the effectiveness of antimicrobial low density polyethylene films (LDPE), with dispersed silver nanoparticles (AgNPs) added in a silicon carrier, in different concentrations of parts per million (ppm) for each polymeric film. Methodology: In this research, six different concentrations of AgNPs (ppm) were studied (1,50; 3,75; 7,50; 15,00; 30,00; 60,00 e 75,00) in nanostructured films, which were characterized by: Field-Emission Gun Scanning Electron Microscopy (FEG - SEM), Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD). The antimicrobial action was tested against different microorganisms, Gram-positives: Staphylococcus aureus and Enterococcus faecalis, and Gram-negatives: Escherichia coli, Salmonella typhimurium and the fungus Penicillium expansumi. Methodologies employed were antimicrobial activities by contact, shake flasks tests and bacterial images by electronic scanning microscopy (ESM). Results: the addition of AgNPs in the matrix of LDPE did not interfere in the physicochemical and the thermal properties of the films. The analysis of antimicrobial activities by contact showed that the nanostructured films were effective in the inhibition of all the studied microorganisms, with greater action on Gram-negative bacteria and fungi than on Gram-positive bacteria. By the shake flasks test it was verified that the nanostructured films help to reduce growth rate and maximum concentration, with increasing in lag stage duration and observing that the bigger the addition of AgNPs, more effective the inhibiting action (p ≤ 0,05). In electronic scanning microscopy (ESM) it was observed that bacteria in contact with AgNPs presented change in microbial wall struture. Conclusion: the nanostructured films presented a promising antimicrobial action with the studied microorganisms. Hence, silver nanoparticles films have a potential use in food packing, helping to reduce cases of food-borne diseases and contributing to reductions in food waste.
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nanotecnologia, nanopartículas de prata, antimicrobiana, embalagens ativas, antimicrobian, nanotechnology, silver nanoparticles, active packs