Navegando por Palavras-chave "Membranes"
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- ItemAcesso aberto (Open Access)Desenvolvimento de algoritmo de seleção de filtros microbiológicos aplicados em processo produtivo de soluções líquidas(Universidade Federal de São Paulo, 2023-07-18) Silva, Mayara Strini da [UNIFESP]; Bresolin, Igor Tadeu Lazzarotto [UNIFESP]; http://lattes.cnpq.br/5750111176589237; http://lattes.cnpq.br/3250340793464660Com a pretensão de obter máxima segurança para seus produtos, uma companhia multinacional, após sofrer um grande incidente microbiológico na produção de enxaguante bucal, decidiu implementar o uso de sistema de filtros absolutos esterilizantes de membrana de 0,2 μm de diâmetro de poro. A observação de altos investimentos nessa aplicação inadequada ao sistema produtivo, motivou um estudo que revelou uma opção de membrana microbiológica compatível com as condições de produção e 82,7% mais barata. A concentração de especialistas dentro de empresas fornecedoras de membranas filtrantes e o alto custo para experimentações leva, muitas vezes, à aplicações inadequadas de tecnologias que já são consideradas maduras. O desenvolvimento de um processo de separação por membranas conta com embasamento teórico e prático e, para melhor direcionar e trazer agilidade para sua implementação faz-se necessária uma metodologia de seleção mais assertiva e eficiente da membrana de filtração no processo de produção de soluções líquidas. O dimensionamento dos filtros por teste de filtrabilidade considerando as condições de produção (variação de pressão, volume, vazão do fluxo, temperatura) juntamente com a caracterização do fluido e membrana utilizada, são o suporte técnico da recomendação para o algoritmo de seleção de membranas. Os resultados foram avaliados paralelamente ao estudo de custos dos diferentes meios filtrantes para a microfiltração com o intuito de justificar o custo agregado ao processo de manufatura. No entanto, a escolha dos tipos de filtros prioriza a garantia do atendimento aos objetivos do fabricante e manutenção das características físico-químicas da solução pré filtração.
- ItemAcesso aberto (Open Access)Desenvolvimento de Dashboard via Power BI para visualização e sistematização de parâmetros da qualidade das águas(Universidade Federal de São Paulo, 2023-10-16) Belati, Leticia Cecilia de Oliveira [UNIFESP]; Silva, Heron Dominguez Torres da [UNIFESP]; http://lattes.cnpq.br/2253809699898165; https://lattes.cnpq.br/6438643517032150O presente projeto visa consolidar e tratar dados de tratamento de água por meio de uma ferramenta de fácil navegação (Dashboard do “Power BI”), abrangendo dados físico-químicos, padrão microbiológico, substâncias químicas de risco à saúde humana e vários outros parâmetros das águas dos mananciais e/ou reservatórios da região da Região Sudeste do país. Com esse consolidado espera-se demonstrar que é simples abordar o tópico da potabilidade da água humana conforme o que está disposto na Portaria nº 888, de 04 de maio de 2021 do Ministério da Saúde do Brasil.
- ItemAcesso aberto (Open Access)Estudo de propriedades biofísicas de vesículas unilamelares gigantes como modelo para entrega intracelular de materiais: eletroporação e fusão de membranas(Universidade Federal de São Paulo (UNIFESP), 2016-11-30) Lira, Rafael Bezerra de [UNIFESP]; Riske, Karin Do Amaral [UNIFESP]; http://lattes.cnpq.br/9178927522709552; http://lattes.cnpq.br/9253308829387337; Universidade Federal de São Paulo (UNIFESP)Biological membranes are the structures that define the boundaries of cells, acting as a selective barrier, regulating the intra and extracellular transport. Many biological substances have their target in the cell?s interior, but are not able to cross the membrane to reach them. Therefore, many methods for the intracellular delivery of materials have been developed; among them, electroporation and fusogenic liposomes. During electroporation, one or more intense electrical pulses are applied and the membrane becomes transiently permeable, allowing the entry of the substances into the cell. The method is efficient but has high toxicity. The fusion between liposomes and cells results in the delivery of the liposome-encapsulated substance, but the underlying mechanisms are not well known and the efficiency is limited. Biomimetic models are generally employed to mimic real systems in a controlled way. One of the most common biomimetic system are the giant unilamellar vesicles (GUVs). In this thesis, we use GUVs with mixed the zwitterionic (PC) and anionic (PG) lipids to study the processes of electroporation and fusion with fusogenic liposomes, and both processes are studied by a series of microscopy-based techniques. Electroformed pores in electrically neutral GUVs are transient, with a pore lifetime in the order of a few milliseconds. In contrast, electroformed pores in some negatively charged GUVs open indefinitely, leading to a total vesicle collapse, in a process termed bursting. The results presented here show that the bursting fraction depends on the fraction of PG in the membrane, lipid insaturation (lipids with insaturation in one or both hydrophobic tails) e certain additives in the medium, especially Ca+2. Bursting propensity is related to the reduction n pore edge tension (?), from 57,9±26,1 e 53,7±11,5 pN in neutral POPC and DOPE membranes, respectively, to values lower than 20 pN in membranes containing PG ? 20 mol%. Such a reduction also depends on the presence of médium additives, and the ? values are higher for vesicles in the presence of Ca+2 compared to Na+, but only in the presence of PG ? 20 mol%. Destabilization propensity is, therefore, a result of a reduction in ?. Formed pores in charged membranes have a composition similar to that in intact membranes. Reminiscent pores after GUV electroporation have a higher permeability to macromolecules. Negative membranes also display differences in other membrane properties compared to neutral ones, such as reduction in lipid mobility, increase in membrane order and spontaneous curvature. The fusion of GUVs with different fractions of PG in PC membranes, with fusogenic liposomes, was studied in a new LUV-GUV fusogenic system, in which fusion was observed in real time and its effects directly observed and quantified under the microscope. In this system, many fusion intermediates (adhesion, hemifusion and full-fusion) can be detected and the morphological transformations directly observed. Förster resonance energy transfer (FRET) assays allow to measure the amount of lipids transferred from the LUVs to the GUVs, and show that the transition hemifusion6 full fusion occurs in the range of 10-20 mol% PG. At low PG mol fractions (? 10 mol%), the interaction leads mainly to adhesion and hemifusion and increases membrane tension, whereas at high PG mol fractions (? 20 mol%), the interaction results in full fusion, leading to GUV increase in area. The construction of a FRET calibration curve allows the determination of the final membrane composition after fusion in every GUV. During hemifusion, the amount of cationic lipids transferred fro LUVs is < 5 mol%, whereas upon full fusion, the final GUV composition contains up to 20 mol% DOTAP. In every case, fusion occurs by a charge neutralization mechanism. The results presented here (i) clarifies the responsible mechanisms of bursting of negatively charged GUVs, (ii) define the membrane charge determinants of fusion in a system of membranes with opposite charges and, (iii) show that many properties of electrically membranes are distinct from their neutral counterparts. We believe that the findings presented here may help on the development of better delivery systems, with better efficiency and lower side effects.
- ItemAcesso aberto (Open Access)Interação de moléculas sintéticas anfifílicas catiônicas com modelos miméticos de biomembranas(Universidade Federal de São Paulo (UNIFESP), 2018-09-27) Almeida, Marcio Moreira de [UNIFESP]; Riske, Karin do Amaral [UNIFESP]; http://lattes.cnpq.br/9178927522709552; Universidade Federal de São Paulo (UNIFESP)Bacterial infections represent a serious health problem, aggravated by the resistance of these microorganisms to conventional antibiotic agents. Therefore, alternative treatments, such as those based on antimicrobial peptides and synthetic molecules with similar characteristics, have been recently sought. Antimicrobial peptides are amphiphilic and cationic molecules present in the immune system of plants and animals that cause the death of microorganisms through the destruction of their membrane. In this work, two classes of synthetic cationic amphiphilic molecules with possible antimicrobial action were studied. These molecules consist of two hydrocarbon chains and two ammonium groups, located at the ends of the hydrophobic chains (Bolalike) or polar region of the molecule (Geminilike). In addition, different lengths of amphiphilic hydrocarbon chains were tested. The molecules studied were B7, B11, G7 and G11, where the letter identifies the class (Bola or Gemini) and the numbers the length of the acyl chain. To understand the mechanism of action of these molecules, membrane mimetic models were used: large (LUVs) and giant (GUVs) unilamellar vesicles composed of POPC, a zwitterionic lipid, and POPG, an anionic lipid. The composition of POPC:POPG 7:3 was chosen to mimic bacterial membranes, whereas pure POPC bilayers were used as biomimetic model of eukaryotic membranes. Different techniques were used to evaluate the interaction between the amphiphilic molecules and the LUVs: isothermal titration calorimetry (ITC), to obtain information about the thermodynamics of the interaction, dynamic scattering (DLS) and zeta potential of the vesicles to measure the size and surface charge of the vesicles as the cationic molecules were added, and leakage assays of a fluorescence probe encapsulated in the LUVs to quantify the lytic activity of the molecules. In addition, GUV optical microscopy experiments were performed to visualize the effects caused by amphiphilic molecules on the membrane. The results show that both the hydrophilic and hydrophobic balance of the molecules and the positions of the charges (Bola or Gemini) have an effect on the activity and mechanism of action of these molecules. Geminilike molecules showed greater affinity for the membrane, but this affinity did not result in a considerable membrane permeabilization. On the other hand, even though Bolalike molecules did not exhibit such high membrane affinity, they caused considerable membrane permeabilization. Among the amphiphilic molecules tested, the molecule B11 presented a lytic activity comparable to that of antimicrobial peptides and is, therefore, the most promising molecule as a possible antimicrobial agent.
- ItemSomente MetadadadosRemoval of glyphosate herbicide from water using biopolymer membranes(Elsevier B.V., 2015-03-15) Carneiro, Rafael T. A.; Taketa, Thiago B.; Gomes Neto, Reginaldo J.; Oliveira, Jhones L.; Campos, Estefania V. R.; Moraes, Mariana A. de [UNIFESP]; Silva, Camila M. G. da; Beppu, Marisa M.; Fraceto, Leonardo F.; Univ Estadual Paulista; Universidade Estadual de Campinas (UNICAMP); Universidade Federal de São Paulo (UNIFESP)Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. the adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. the membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. the results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). the AG membrane did not show any adsorption capacity for this herbicide. the pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. the SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. the results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to treat a water sample contaminated with glyphosate. Biopolymer membranes therefore potentially offer a versatile method to eliminate agricultural chemicals from water supplies. (C) 2015 Elsevier B.V. All rights reserved.
- ItemAcesso aberto (Open Access)Rotura prematura das membranas no pré-termo(Universidade Federal de São Paulo (UNIFESP), 1994) Sumita, Satie Lucia Nishimaru [UNIFESP]; Camano, Luiz [UNIFESP]
- ItemAcesso aberto (Open Access)Solubilização de membranas modelo de diferentes composições pelo detergente triton X-100(Universidade Federal de São Paulo (UNIFESP), 2017-03-29) Mattei, Bruno [UNIFESP]; Riske, Karin do Amaral [UNIFESP]; http://lattes.cnpq.br/9178927522709552; http://lattes.cnpq.br/4260343698344529; Universidade Federal de São Paulo (UNIFESP)Detergents are amphiphilic molecules widely used as solubilizing agents Biological membranes. However, biological membranes treated with detergents Ac-ese insoluble fragments rich in sphingolipids and cholesterol. Due to similarities of These features have been associated with lipid rafts and the liquid phase The. Here the study of the physical-chemical aspects that govern the process of UUilllCATiOn of membrane mimetic models: lipid vesicles of controlled composition Pure or mixtures, mainly POPC, SM and cholesterol). Many different Techniques were used to study the solubilization process of lipid vesicles by Detergent TX-100, one of the most used detergents in Biological membranes. The general phenomenon and the size of the structures formed during the Solubilization was obtained by turbidity, static and / or dynamic light scattering; The aspects Thermodynamic properties of the detergent-lipid interaction were investigated by titration calorimetry And the possible interference of the detergent in the phase transition of lipids was investigated Differential scanning calorimetry; The ability of detergents to permeabilize the The membrane was investigated by kinetics of leakage of a fluorescent probe and microscopy Confocal; The process of solubilization of giant vesicles was evaluated by optical microscopy of Phase contrast and fluorescence. In the work, different lipid compositions were investigated (Pure phospholipids, binary lipid mixtures and ternary lipid mixtures) in order to obtain Information on the factors that influence the obtaining of insoluble membrane fragments. Through the experiments it was possible to conclude that pure cell membranes (POPC and SM), reaching the liquid-disordered phase and gel are totally soluble to the action of Detergent, whereas the addition of cholesterol, inducing a higher degree of Lipids leads to conditions in which the membranes are partially or totally insoluble; The factor of Insolubility is conditioned to cholesterol concentration in vesicles with binary mixtures Of lipids, reaching total insolubility in situations in which the membrane tends or reaches the Liquid-ordered phase; This is also reflected in the detergent affinity constant for these Membranes. In addition, vesicles in the gel phase are solubilized with lower concentrations of TX-100 than vesicles in the liquid-disordered phase, possibly due to the lower Ability of the membrane to accommodate detergents; Added to this, the addition of detergent Also appears to induce a phase transition in vesicles in the gel phase and a coexistence of Fluid phases in POPC: cholesterol vesicles. In ternary lipid mixtures, the situations in Higher solubility resistance is observed in regions with Greater fraction of SM and cotesterol. Finally, the membranes become permeable in TX-100 / lipid molars lower than the solubilization process, showing that even before To reach the bi-co-existent phase of the membrane, the detergent already changes the membrane structure.