Abstract Bacterial cellulose (BC) is promising as a wound dressing because it is non- toxic and maintains moisture in the wound. Although BC does not have antimicrobial activity, its structure allows the incorporation of antimicrobial compounds such as essential oils (EOs). This study aims to associate BC with rosemary, clove, eucalyptus, ginger, lavender and lemongrass EOs to obtain wound dressings. The Gas Chromatography-Mass Spectrometry and Fourier Transform Infrared Spectroscopy analyses showed characteristic compounds of EOs in the incorporated membranes. These compounds reduced the thermal stability of most samples due to their different degrees of volatility. The Scanning Electron Microscopy indicated that the EOs filled the membrane pores and coated the cellulose fibers. Samples incorporated with clove, ginger and lemongrass EOs inhibited Escherichia coli, Staphylococcus aureus and Candida albicans due to the presence of eugenol and citral. The results confirmed the incorporation method's effectiveness, maintaining the composition and antimicrobial characteristics of the EOs.

Abstract Bacterial nanocellulose (BNC) membranes have interconnected porous nanostructures and excellent biocompatibility. Functionalizing these with calcium phosphate sources and metal ions confers optimized properties to the biomaterial. This study aims to synthesize BNC membranes, functionalize them with copper and magnesium apatites, characterize and evaluate their cytotoxicity and antimicrobial potential. Membranes were synthesized for 8 days in Mannitol Medium. The biocomposite production was by immersion cycles. The biocomposites were characterized by porosity and swelling capacity, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), antimicrobial properties and cytotoxicity assays. The FTIR and SEM results showed that phosphate groups were incorporated into the BNC. The TGA analysis also indicated the incorporation of the inorganic phase. The membrane functionalization with Cu promoted the antimicrobial properties of the biomaterial. However, functionalization with Mg had a more positive behavior on cell viability, proving to be more suitable for use as an implantable material.

RESUMO Neste trabalho foi desenvolvido um biocompósito biodegradável a base de amido de banana verde (ABV) associado à celulose bacteriana (CB) e glicerina (GL), visando aplicação em produtos de rápida descartabilidade. Para a extração do amido, bananas verdes foram lavadas, cortadas e submersas em bissulfito de sódio a 1%, armazenadas em geladeira por 24 h, trituradas em liquidificador com água destilada e peneiradas. O amido precipitado foi disposto em placas de Petri e seco em estufa a 37 °C. Para avaliação da melhor composição com características hidrofóbicas e hidrofílicas, foi realizado um planejamento fatorial 23 completo com 3 pontos centrais, totalizando 11 amostras, sendo avaliada a influência da concentração de farelo de CB nos níveis 10 e 30 g/L, GL nas concentrações de 0 e 16 g/L e metiltrietoxisilano (MTES) na etapa de silanização nas concentrações de 0 e 4% em solução alcoólica. A análise de ângulo de contato permitiu identificar a hidrofobicidade das amostras comprovando a eficácia da silanização. Com base nas medidas de ângulo de contato das amostras foram produzidos os corpos de prova para caracterização contendo 20 g/L de CB, 8 g/L de GL e 4% de silano, uma vez que quanto maior concentração de silano, maior foi a hidrofobicidade do material. A análise de espectroscopia no infravermelho com transformada de Fourier (FTIR) apontou as bandas características de silano, comprovando a reação química com MTES, sendo também possível constatar a existência do amido, CB e GL. A análise termogravimétrica (TGA) demonstrou que a temperatura de degradação máxima da amostra ABV/FCB/GLcs silanizada (4%) se apresenta em Tmáx3= 310°C. Com o teste de degrabilidade em solo foi possível identificar que as amostras funcionalizadas demoram mais para degradar em comparação com as não silanizadas devido à sua barreira a umidade, característica que desacelera a degradação por microorganismos.

ABSTRACT In this work, a biodegradable biocomposite was developed, the green banana starch (GBS) associated with bacterial cellulose (BC) and glycerin (GL), aiming for application in rapid disposability products. For starch extraction, green bananas were washed, cut and submerged in 1% sodium bisulfite, stored in the refrigerator for 24 h, crumbled in a blender with distilled and sieved water. The precipitated starch was disposed of on Petri dishes and dried in an oven at 37°C. A complete factorial planning was carried out to evaluate the best composition with hydrophobic and hydrophilic characteristics with 3 central points, totaling 11 samples, the influence of BC bran concentration at levels 10 and 30 g/L, concentrations of 0 and 16 g/L and methyltriethoxisilane (MTES) in the silanization stage in concentrations of 0 and 4% in alcoholic solution. The contact angle analysis allowed identifying samples’ hydrophobicity, proving silanization effectiveness. Based on the contact angle measurements of the samples, the proof bodies for characterization were produced containing 20 g/L of BC, 8 g/L of GL and 4% silane since the higher concentration of silane, the greater material hydrophobicity. The infrared spectroscopy analysis with Fourier transform (FTIR) pointed out the silane characteristics bands, proving the chemical reaction with MTES, and it is also possible to see the existence of starch, BC and GL. Thermogravimetric analysis (TGA) demonstrated that the maximum degradation temperature of the sample GBS /FBC/GLcs silanized (4%) is Tmax3= 310 °C. With the soil degradability test, it was possible to identify that the functionalized samples take longer to degrade than those not silanized because of their barrier moisture, a characteristic that slows down microorganisms’ degradation.

ABSTRACT This work aimed to obtain and characterize bacterial cellulose (BC) membranes obtained by cultivating Komagataeibacter hansenii ATCC 23769 using mannitol, glucose, fructose, lactose, glycerol, inulin, and sucrose as carbon sources, and corn steep liquor and Prodex Lac® as alternative sources of nitrogen. The formation of the BC´s gelatinous membrane was monitored for 12 days under static conditions and a temperature of 30 ºC. After purification, the membranes were dried and characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The highest BC concentrations were found in the culture medium containing Prodex Lac® as the source of nitrogen. Among sugars, fructose and mannitol presented the best results. TGA analyzes indicate that all membranes have similar thermal behavior. The FTIR results show that the chemically synthesized membranes are equivalent to the structures cited in the literature. The micrographs obtained by SEM showed that the medium might influence BC´s morphology, but in general, all presented nanofibers, an essential feature in the membrane. Thus, the BC membranes synthesized in this study proved that the BC production using low-cost alternative means is feasible. The material obtained meets the expected thermal, physical, and chemical properties.

This work aimed to synthesize bacterial cellulose (BC) membranes functionalized with Ce(NO3)3 and silver nanoparticles (AgNPs) heat-treated in oven and autoclave. The AgNPs were characterized by TEM and the membranes were characterized by their rehydration capacity, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy with Dispersive Energy Spectroscopy (SEM/EDS), Wide-angle X-ray Diffractometry (XRD), Atomic Absorption Spectroscopy (AAS), antimicrobial activity and cytotoxicity. The BC membranes were white to light yellow or brown indicating functionalization with AgNps with 20 nm. XRD detected a decrease in the degree of crystallinity in functionalized membranes. The autoclaved samples exhibited the largest porosity and good rehydration capacity. AAS showed Ag presence in all samples. The best antibacterial activity was achieved for the membrane’s oven treated with 40 ppm of AgNPs. Among the functionalized membranes, the most recommended to be used as burn dressing is the Ag40A and Ag20CN1.1A since they showed good porosity, good antimicrobial activity, and better suitable cell viability.

ABSTRACT Glycerol was used as a source of additional carbon in the production of Poly(3-hydroxybutyrate) (P(3HB)). The inverted sugar and glycerol concentrations and the temperature of the Cupriavidus necator culture medium were evaluated using a Central Composite Rotational Design (CCRD). The results showed that the increase in temperature and sugar concentration led to an increase in production and P(3HB) accumulation and when 15 g L−1 of glycerol was added better results were obtained, however these were not considered statistically significant. The best results were obtained at 38 °C and with 30 g L−1 of inverted sugar. Although not considered statistically significant, the addition of 15 g L−1 of glycerol increased the P(3HB) accumulation percentage by 15 %, thus in kinetic terms, greater productivity was obtained in 0.32 g L−1 h−1 polymer. Larger scale assays are being conducted to verify if the addition of glycerol improves the thermal and mechanical properties of the synthesized polymer.

Resumo Poli(3-hidroxibutirato) [P(3HB)] é um poliéster natural, biodegradável e é considerado um substituto atrativo para polímeros petroquímicos, pois tem a vantagem de ser degradado em solo dentro de alguns meses por micro-organismos. Este trabalho explora três estratégias para sintetizar P(3HB) a partir de Cupriavidus necator tendo glicerol como cosubstrato: cultivo sem glicerol, com adição de 20 g L–1 de glicerol na fase de produção do polímero e 20 g L–1 de glicerol no início do cultivo, a fim de avaliar o seu efeito sobre o crescimento celular e a síntese do polímero. Os resultados mostraram que a adição de glicerol no início do cultivo conduziu a maiores valores de percentagem de acúmulo de P(3HB) (64,12%). No entanto, nos experimentos sem glicerol podem ser observados maiores valores para fator de conversão em substrato (0,17 g g–1). Esses parâmetros apresentaram diferenças estatisticamente significativas em função da estratégia de cultivo utilizado.

Abstract Poly(3-hydroxybutyrate) [P(3HB)] is a natural, biodegradable polyester and is considered an attractive substitute for the petrochemical polymers, because has advantage of being degraded in the soil within a few months by microorganisms. This work exploits three strategies to synthesize P(3HB) from of the Cupriavidus necator with glycerol as co-substrate: cultivation without glycerol, with addition of 20 g L–1 glycerol in the phase of polymer producing and addition of 20 g L–1 of glycerol at the start of cultivation, in order to evaluate its effect on cell growth and the synthesis of the polymer. The results showed that the addition of glycerol at the start of culture led to highest values of accumulation percentage the P(3HB) (64.12%). However, in the experiments without glycerol can be observed higher values toward biomass to substrate yield (0.17 g g–1). These parameters presented statistically significant differences in function of the cultivation strategy used.

ABSTRACT Glycerol was used as a source of additional carbon in the production of Poly(3-hydroxybutyrate) (P(3HB)). The inverted sugar and glycerol concentrations and the temperature of the Cupriavidus necator culture medium were evaluated using a Central Composite Rotational Design (CCRD). The results showed that the increase in temperature and sugar concentration led to an increase in production and P(3HB) accumulation and when 15 g L-1 of glycerol was added better results were obtained, however these were not considered statistically significant. The best results were obtained at 38 °C and with 30 g L-1 of inverted sugar. Although not considered statistically significant, the addition of 15 g L-1 of glycerol increased the P(3HB) accumulation percentage by 15 %, thus in kinetic terms, greater productivity was obtained in 0.32 g L-1 h-1 polymer. Larger scale assays are being conducted to verify if the addition of glycerol improves the thermal and mechanical properties of the synthesized polymer.

RESUMO As resinas epóxi em gel coat utilizadas em laminação de moldes precisam conferir à peça um alto brilho e homogeneidade, garantindo a qualidade estética e as propriedades mecânicas. Desta forma, o presente trabalho objetivou estudar a formulação de compósitos de resina epóxi/cargas inorgânicas visando à melhoria das propriedades físicas e mecânicas. Foi realizado um planejamento experimental 23 completo com três pontos centrais, totalizando 11 formulações de compósito de resina epóxi gel coat, nas quais foram avaliadas a influência das cargas dióxido de titânio (TiO2) (20, 45 e 70 phr), calcita (0, 20 e 40 phr) e barita (0, 20 e 40 phr) nas propriedades físicas, densidade e nível de escorrimento e na dureza. Foram observadas variações consideráveis nas propriedades dos compósitos com as modificações realizadas nas formulações. Verificou-se no planejamento experimental, que a variável densidade foi significativa em relação às três variáveis independentes e não significativa na falta de ajuste, deste modo, o modelo representou adequadamente o comportamento experimental. Para a variável dureza, o modelo linear não descreveu satisfatoriamente a influência das cargas. De acordo com os ensaios realizados, observou-se que com a redução de TiO2 caracterizou um aumento na dureza, portanto, uma redução na densidade. Por outro lado, a barita exerceu uma influência positiva nas duas propriedades e a calcita não apresentou influência significativa. Em relação ao nível de escorrimento, as amostras que apresentaram maiores quantidades de cargas, foram as que melhor se comportaram nessa propriedade. Finalmente, foi realizada uma nova formulação que foi validada pelo modelo da densidade (60 partes de TiO2, 30 partes de calcita e 20 partes de barita) que atendeu as especificações.

ABSTRACT The gel coat epoxy resins used in mold lamination need to give the piece a high gloss and homogeneity, guaranteeing aesthetic quality and mechanical properties. In this way, the present work aimed to study the formulation of epoxy resin composites/inorganic fillers aiming at the improvement of physical and mechanical properties. A complete experimental design was carried out with three central points, totaling 11 formulations of epoxy gel coat composite, in which the influence of titanium dioxide (TiO2) (20, 45 and 70 phr), calcite (0, 20 and 40 phr) and barite (0, 20 and 40 phr) in the physical properties, density and drainage level and hardness. Considerable variations were observed in the properties of the composites with the modifications made in the formulations. It was verified in the experimental planning that the variable density was significant in relation to the three independent variables and not significant in the lack of fit, in this way, the model adequately represented the experimental behavior. For the variable hardness, the linear model did not satisfactorily describe the influence of the loads. According to the tests carried out, it was observed that with reduction of TiO2 characterized an increase in hardness, therefore, a reduction in density. On the other hand the baryta exerted a positive influence on the two properties and the calcite did not present significant influence. Regarding the level of runoff, the samples that presented the greatest amount of loads were the ones that performed best on this property. Finally, a new formulation was performed that was validated by the density model (60 parts TiO2, 30 parts calcite and 20 parts barite) that met the specifications.

RESUMO Este trabalho almejou produzir celulose bacteriana (CB), obter nanocristais de celulose bacteriana (NCCB), incorporar NCCB como reforço em poli(L-ácido láctico) (PLLA) e avaliar propriedades destes bionanocompósitos. Foram produzidas membranas de CB provenientes da bactéria Gluconacetobacter hansenii. A partir das membranas foram obtidos NCCB por hidrólise com ácido sulfúrico (H2SO4), com base em 11 experimentos. Os parâmetros variados nos experimentos foram: concentração de H2SO4, temperatura e tempo. Pode-se definir critérios de obtenção de NCCB por análise termogravimétrica (TGA) e análise de espalhamento dinâmico de luz (DLS). Principais resultados indicam possibilidade de obtenção na condição de: 80% de concentração de H2SO4 (m/m), 60 ºC e 60 min. Para esta condição obteve-se tamanhos adequados dos NCCB (média de 388 nm), potencial zeta adequado (-38 mV) e estabilidade térmica adequada (Tonset2 = 301,9 ºC). Posteriormente, NCCB obtidos conforme critérios definidos foram incorporados ao PLLA em duas concentrações (2,5 e 5%), utilizando dois métodos (sem e com funcionalização dos NCCB). Os bionanocompósitos preparados foram caracterizados por TGA e calorimetria explanatória diferencial (DSC). Resultados das técnicas de caracterização dos bionanocompósitos foram comparados com resultados do PLLA puro. Principais resultados em relação aos métodos, revelam a importância da funcionalização dos NCCB antes de incorporá-los ao PLLA. Sobre a concentração de reforço utilizada, o aumento da estabilidade térmica foi gradual, conforme teor de reforço, sendo que para o bionanocompósito com 5% de NCCB funcionalizados o incremento foi de 10,4 ºC na Tonset2 em relação ao PLLA puro. Contudo, o grau de cristalinidade diminuiu (Xc do PLLA puro = 40,38% e Xc do bionanocompósito com 5% de NCCB funcionalizados = 24,73%). Conclui-se que a adição de NCCB em PLLA é ambientalmente viável e promove melhoria de propriedades.

ABSTRACT This work aimed to produce bacterial cellulose, to obtain bacterial cellulose nanocrystals, to incorporate nanocrystals as a reinforcement in poly(L-lactic acid) and to evaluate the properties of these bionanocomposites. Bacterial cellulose membranes from the bacterium Gluconacetobacter hansenii were produced. From the membranes were obtained nanocrystals by hydrolysis with sulfuric acid (H2SO4), based on 11 experiments. The parameters varied in the experiments were: concentration of H2SO4, temperature and time. It is possible to define criteria for obtaining nanocrystals by thermogravimetric analysis and analysis of dynamic scattering of light. Main results indicate the possibility of obtaining in the condition of: 80% concentration of H2SO4 (m/m), 60 °C and 60 min. For this condition, suitable sizes of the nanocrystals (mean 388 nm), suitable zeta potential (-38 mV) and adequate thermal stability (Tonset2 = 301.9 °C) were obtained. Subsequently, nanocrystals obtained according to defined criteria were incorporated into poly(L-lactic acid) in two concentrations (2,5 and 5%), using two methods (without and with functionalization of nanocrystals). The prepared bionanocomposites were characterized by thermogravimetric analysis and differential explanatory calorimetry. Results of the techniques of characterization of bionanocomposites were compared with results of pure poly(L-lactic acid). Main results regarding the methods, reveal the importance of the functionalization of the nanocrystals before incorporating them to the poly(L-lactic acid). On the reinforcement concentration used, the increase of the thermal stability was gradual, according to reinforcement content, and for the bionanocomposite with 5% functionalized nanocrystals the increase was of 10,4 ºC in the Tonset2 in relation to the poly(L-lactic acid) pure. However, the degree of crystallinity decreased (Xc of pure PLLA = 40,38% and Xc of bionanocomposite with 5% of functionalized nanocrystals = 24,73%). It is concluded that the addition of bacterial cellulose nanocrystals in poly(L-lactic acid) is environmentally feasible and improves properties.

Processos de desidratação e de rehidratação de cogumelos da espécie Pleurotus ostreatus foram avaliados neste trabalho. Os cogumelos foram desidratados a 40, 50 e 60 ºC, com umidade relativa do ar de 75 %. O processo de rehidratação foi avaliado para diferentes temperaturas de água de imersão (25, 55 e 85 ºC) e diferentes tempos de imersão (30, 75 e 120 minutos). A melhor temperatura de secagem foi 40 ºC, levando em consideração a melhor rehidratação dos cogumelos desidratados nesta temperatura. A rehidratação pode ser feita em água a temperatura ambiente, por 30 minutos. Isotermas de sorção de umidade de amostras foram determinadas a 30, 40 e 50 ºC.Tanto o modelo de GAB quanto o de BET representaram satisfatoriamente os dados experimentais de isoterma de sorção de umidade.

Dehydration and rehydration processes of Pleurotus ostreatus fruiting bodies were investigated in this work. Mushroom samples were dehydrated at 40, 50 and 60 ºC, using drying air with relative humidity of 75 %. The rehydration was investigated at different temperatures of immersion water (25, 55 and 85 ºC) and different immersion times (30, 75 and 120 minutes). The best rehydration occurred for the samples dried at 40 ºC. The rehydration could be done in water at room temperature, during 30 minutes. Water sorption isotherms of samples were determined at 30, 40 and 50 ºC. Both GAB and BET models satisfactorily represented the experimental data of moisture sorption of dried mushrooms.