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.

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.