This work reports on the production of poly(vinylidene fluoride) (PVDF) membranes by non-solvent induced phase separation (NIPS) using N,N-dimethylformamide (DMF) as solvent and water as non-solvent. The influence of the processing conditions in the morphology, surface characteristics, structure, thermal and mechanical properties were evaluated for polymer dissolution temperatures between 25 and 150 C and conditioning time between 0 and 10 min. Finger-like pore morphology was obtained for all membranes and increasing the polymer dissolution temperature led to an increase in the average pore size ( 0.9 and 2.1 m), porosity ( 50 to 90%) and water contact angle (up to 80 ), in turn decreasing the PVDF content ( 67 to 20%) with the degree of crystallinity remaining approximately constant ( 56%). The conditioning time did not significantly affect the polymer properties studied. Thus, the control of NIPS parameters proved to be suitable for tailoring PVDF membrane properties.

Mesoporous separator membranes based on poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, were prepared through the removal of ZnO nanoparticles from the polymer matrix composite. Different filler concentrations were used, and the evaluation of the morphology, mechanical properties, uptake and ionic conductivity of the membranes were demonstrated that they depend on initial ZnO content in the composite. On the other hand, the vibration peaks characteristics of PVDF-TrFE and the thermal properties are independent on initial filler content. The membrane with the best ionic conductivity, 1.6 mS/cm, is the one prepared after 70 wt.% ZnO removal. The separator membranes were assembled in Li/C-LiFePO4 half-cells exhibiting good rate capability and cycling performance, the best battery performance being obtained for the PVDF-TrFE after 70 wt.% ZnO removal. The good performance of the developed separators was also demonstrated in full battery cells. Thus, a way to tailor membrane mesoporosity is presented and it is shown that the obtained membranes represent suitable separators for lithium-ion battery applications.

The huge efforts for the achievement of highly purified biomolecules are growing every day. A great number of efficient techniques, such as chromatography, are already available in laboratory for separation processes. However, membrane‐based technologies are the best match to assure simplicity, efficiency and easy scale‐up procedures. Herein we report the modification of a commercial microfiltration membrane for plasmid DNA purification by agarose gel impregnation. The membrane was characterized by SEM, ATR‐FTIR, EDS, contact angle, and porosity measurements. Additionally, the membrane pore radius was estimated from observed rejections of different proteins and with that information the rejection of a 6050 bp plasmid DNA (pDNA) molecule was estimated for different values of flux using a theoretical model of large flexible molecules in membranes with parallel cylindrical pores, which is applicable to pDNA ultrafiltration in conventional membranes, as recently shown in the literature. The experimental results show that the modified membrane has higher pDNA rejections than the predicted by the model, suggesting that the different type of porous structure that a hydrogel has, may have a positive effect on pDNA rejections as compared to other biomolecules with more rigid structures, making this type of modified membranes potential better candidates to be used for the selective recovery of pDNA in this type of bioprocesses.

Bioinspired and adhesive multilayer membranes are produced using the layer-by-layer (LbL) assembly of chitosan (CHT), alginate (ALG) and hyaluronic acid modified with dopamine (HA-DN). Freestanding multilayer membranes without DN are also produced as a control. The success of the synthesis of HA-DN was confirmed using UV-visible spectroscopy. Scanning electron microscopy images indicate that the surface of the DN-containing membranes is more porous than the control ones; they also present a higher average thickness value for the same number of CHT/ALG/CHT/HA(-DN) tetralayers (n = 100). Also, water uptake, mechanical strength and adhesion are enhanced with the introduction of DN moieties along the nano-layers. Besides, human dermal fibroblast viability, enhanced adhesion and proliferation were confirmed by immunofluorescence assays and by measuring both the metabolic activity and DNA content. Moreover, in vivo assays with such kinds of DN-containing multilayer membranes were performed; the application of these membranes in the treatment of dermal wounds induced in Wistar rats results in the highest decrease of inflammation of rat skin, compared with the control conditions. Overall, this investigation suggests that these mussel-inspired freestanding multilayer membranes may enhance either their mechanical performance or cellular adhesion and proliferation, leading to an improved wound healing process, being a promising material to restore the structural and functional properties of wounded skin.

O objetivo da presente dissertação consiste em desenvolver e avaliar o potencial de membranas de acetato de celulose pura e híbridas, contendo compostos a base de titânio / silício / nitrogênio, para atenderem a vasta gama de aplicação dos materiais híbridos. Para esse efeito, foram sintetizadas membranas via processo sol gel e inversão de fases, através de três precursores, ortossilicato de tetraetila (TEOS), 3-aminopropril trietoxissilano (APTES) e o isopropóxido de titânio (TiPOT), na presença de ácido nítrico (HNO3). Foram testadas diferentes concentrações de 0, 25, 50, 75 e 100 % (m/m) de TEOS e APTES, em que para o acetato de celulose e o TiPOT tiveram suas concentrações fixas. As membranas sintetizadas foram caracterizadas com espectroscopia na região do infravermelho com transformada de Fourier, FTIR, e análise termogravimétrica, TG/DTG. Além da cinética de degradação térmica com 3 métodos, Friedman, Flynn e Kissenger. Foram comprovadas através da espectroscopia a presença das ligações e grupos funcionais característicos das membranas de acetato de celulose híbridas. As análises térmicas permitiram avaliar a presença de eventos de perda de massa, mostrando a presença de um processo de degradação complexo. A cinética de degradação afirmou que a modificação na composição aumenta a resistência térmica das amostras. Isto é mostrado pelo aumento da energia de ativação da membrana pura, ACPURO, 248,85; e para a B100//0-30, 482,13 KJ/mol. Estes resultados foram da primeira batelada e usando o método de Friedman. O comportamento comparativo dessas duas amostras, AC-PURO e B100//0-30, se manteve nos outros métodos aplicados, correspondendo a uma variação de 233,3 a 452,73 KJ/mol para a primeira batelada no método de Flynn e de 241,06 a 467,04 KJ/mol na primeira batelada pelo método de Kissenger. Foi observado durante a análise, que principalmente o aumento no teor de TEOS, atribuiu as amostras maior estabilidade térmica e química.

Apesar de o Brasil não possuir uma legislação específica que norteie o reuso de efluentes industriais e suas possibilidades de aplicações, as indústrias vêm buscando alternativas internas com utilizações menos nobres, tais como a irrigação e a lavagem de pisos. Nos últimos anos o reuso de efluentes na indústria vem crescendo devido à competitividade mercadológica e para obtenção de certificações ambientais. Neste cenário, o reuso da água se tornou uma questão de sobrevivência, de tal forma que as indústrias passaram a fomentar a otimização de processos com a consequente redução de custos. O objetivo desta pesquisa foi de avaliar a possibilidade técnica e econômica de reuso do efluente tratado de uma indústria farmacêutica ao adotar o processo de ultrafiltração como tratamento terciário. A pesquisa envolveu três etapas: a primeira avaliou a performance da ETEI através da caracterização dos efluentes lançados na rede da CEDAE; a segunda realizou testes de ultrafiltração em escala laboratorial, com observações quanto à eficiência na remoção de sólidos e à qualidade do efluente obtido pelo processo de separação com membranas; a terceira avaliou os aspectos econômicos referente a aquisição do sistema de ultrafiltração em escala industrial e os custos operacionais envolvidos. Os resultados da primeira etapa mostraram que a ETEI da indústria farmacêutica atende aos padrões de controle estabelecidos pelo Instituto Estadual do Ambiente - INEA. Para segunda etapa os resultados evidenciaram que o processo de separação por membranas de ultrafiltração foi eficaz na remoção de turbidez e sólidos suspensos totais, com eficiências de 99,9% e 97,9%, respectivamente. A planta de ultrafiltração em escala laboratorial reduziu consideravelmente o parâmetro de turbidez, obtendo-se o resultado do permeado com o valor máximo de 0,2 uT. Neste caso o efluente pode ser utilizado para lavagem de pisos, irrigação e uso em vasos sanitários, segundo os parâmetros indicados pela USEPA (2012) e PROSAB (2006). Em relação aos parâmetros dureza total e pH e os indicadores de Langelier e Ryznar, o efluente não está apto para ser reutilizado em caldeiras. Quanto aos aspectos econômicos, a pesquisa estimou o payback após 2,2 anos de operação do sistema, considerando a geração de 200 m3mês-1 de água de reuso, com economia bruta anual de R$ 126.120,00 (Cento e vinte seis mil e cento e vinte reais).

O objetivo deste trabalho foi estudar a remoção de metais pesados de efluentes sintéticos aquosos através de nanofiltração, com utilização de membrana de poliamida. A membrana utilizada constituída de poliamida apresentou uma boa permeabilidade hidráulica, constatada pela linearidade de fluxo com a variação de pressão de trabalho. Os metais estudados foram cobre, cádmio, zinco, chumbo e níquel com especiação de nitrato e sulfato. O desempenho do sistema foi verificado pela variação dos parâmetros operacionais (pressão e fluxo), associados também com a variação da salinidade e da concentração do metal. Em uma etapa inicial estudou-se a remoção de metais (nitrato e sulfato) isoladamente em uma mesma concentração molar, na pressão de 10 bar, comparando-se as rejeições com e sem agente complexante (EDTA). Em uma segunda etapa, estudou-se o desempenho da membrana, com misturas dos metais (nitrato) e mistura de metais (sulfato), também com e sem agente complexante, os resultados mostraram que a presença de agente complexante melhorou a rejeição dos metais. Nestas misturas estudaram-se os efeitos das concentrações (0,001; 0,0005 e 0,0001mol/L) e das pressões (5; 7; 10 e 12,5 bar) no sistema de remoção, constatou-se que o aumento da concentração e diminuição da pressão afeta a remoção. Em uma terceira etapa, estudou-se a influência da salinidade pela mistura de dois metais de mesma especiação (sulfato), comparando a remoção na pressão de 10 bar. Os resultados atestaram uma rejeição maior que 94 % para todos metais, na pressão de 10 bar, indicando um excelente desempenho e fluxo adequado, daí viabilidade de processo para todas as concentrações testadas. A pertinência do teste se justifica pela adequação do permeado ao atendimento aos padrões ambientais de concentração de metais e confirmam a eficácia do sistema de nanofiltração na remoção de metais pesados

This work focuses on the valorization of residues, in this case, the crayfish by using it as raw material in the process of chitosan extraction. It also involves a study of the characteristics and properties of chitosan, to develop a membrane for the treatment of vaginal infections. The first step was the extraction of chitin from the crayfish shell. This was done using a chemical extraction method, characterized by successive reactions at different temperatures. The reactions consist in extracting the pigment astaxanthin with acetic acid, bleaching with NaClO, HCl solution for demineralization, and finally deproteinization with NaOH. The result was chitin, dried for 24 h at 50 ºC. This process had a yield of 8.42±3.35%. The extracted chitin was characterized with FTIR analysis and presents an acetylation degree of 97.6±0.2 %. Additionally, by acid hydrolysis, the percentage of pure chitin in female and male crayfish samples was determined. Females presented a higher percentage. Proceeded to the transformation of chitin into chitosan, and characterization. The deacetylation of chitosan was optimized, occurring NaOH solution in a ratio of 1:15 (m of chitin / v of NaOH solution), 5 h in a thermal bath at 100 ºC, and then 5 h at 130 ºC. The yield of this process was 63.4 ± 18.4 %, and the chitosan obtained presented a degree of deacetylation of 64.5 ± 0.2 %. A physical-chemical characterization using FTIR, DSC, XRD, and zeta-potential analysis was carried out. Bioactivities properties, antioxidant, and antimicrobial were evaluated. The microorganisms tested and for which it showed any antimicrobial capacity were gram-positive bacteria (methicillin-resistant Staphylococcus aureus and methicillin-sensitive Staphylococcus aureus), gram-negative (Escherichia coli), and fungi (Candida albicans).It was decided to develop an application in the field of biomedicine, exploring its potential as an antimicrobial agent. The final phase consisted of the production of chitosan membranes for the treatment of vaginal infections. It required the evaluation of their behavior, absorption, and degradation after immersion in a simulated vaginal fluid solution. The antimicrobial activity was also evaluated for typical pathogens of vaginal infections, and against Lactobacillus spp., common in the vaginal microbiota. The membranes produced with chitosan extracted from crayfish inhibited the growth of microorganisms. They also inhibited Lactobacillus spp., and, for this reason, the addition of probiotics/prebiotics in the formulation of the membranes is suggested. The membranes proved to be promising, being necessary adaptations, optimization of the production.

Two HIV-1 recognition domains for the human monoclonal ACHTUNGTRENUNGantibodies (MAb) 2F5, which recognises the core sequence ELDKWA, and 4E10, which recognises the core sequence NWFNIT, serve as promising models for immunogens in vaccine development against HIV-1. However, the failure of these recognition domains to generate broadly reactive neutralizing antibodies, and the putative membrane-binding properties of the antibodies raised to these recognition domains, suggest that additional features or recognition motifs are required to form an efficient immunogen, which could possibly include the membrane components. In this study we used an extended peptide epitope sequence derived from the gp41 native ACHTUNGTRENUNGsequence (H-NEQELLELDKWASLWNWFNITNWLWYIK-NH), which contains the two recognition domains for 2F5 and 4E10, to examine the role of model cell (POPC) and viral (POPC/cholesterol/sphingomyelin) membranes in the recognition of these two antibodies. By using a surface plasmon resonance biosensor, the binding of 2F5 and 4E10 to membranes was compared and contrasted in the presence and absence of prebound peptide epitope. The recognition of the peptide epitope by each MAb was found to be distinct; 2F5 exhibited strong and almost irreversible binding to both membranes in the presence of the peptide, but bound weakly in the absence of the peptide epitope. In contrast, 4E10 exhibited strong membrane binding in the presence or absence of the peptide epitope, and the binding was essentially irreversible in the presence of the peptide epitope. Overall, these results demonstrate that both 2F5 and 4E10 can bind to membranes prior to epitope recognition, but that high-affinity recognition of gp41-derived epitope sequences by 2F5 and 4E10 occurs in a membrane context. Moreover, 4E10 might utilise the membrane to access and bind to gp41; such membrane properties of 2F5 and 4E10 could be exploited in immunogen design.

Because of their high activity against microorganisms and low cytotoxicity, cationic antimicrobial peptides (AMPs) have been explored as the next generation of antibiotics. Although they have common structural features, the modes of action of AMPs are extensively debated, and a single mechanism does not explain the activity of all AMPs reported so far. Here we investigated the mechanism of action of Sub3, an AMP previously designed and optimised from high-throughput screening with bactenecin as the template. Sub3 has potent activity against Gram-negative and Gram-positive bacteria as well as against fungi, but its mechanism of action has remained elusive. By using AFM imaging, ζ potential, flow cytometry and fluorescence methodologies with model membranes and bacterial cells, we found that, although the mechanism of action involves membrane targeting, Sub3 internalises inside bacteria at lethal concentrations without permeabilising the membrane, thus suggesting that its antimicrobial activity might involve both the membrane and intracellular targets. In addition, we found that Sub3 can be internalised into human cells without being toxic. As some bacteria are able to survive intracellularly and consequently evade host defences and antibiotic treatment, our findings suggest that Sub3 could be useful as an intracellular antimicrobial agent for infections that are notoriously difficult to treat.