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- ItemAcesso aberto (Open Access)Avaliação da interação molecular de 1,4 naftoquinona em modelos de membrana celular utilizando filmes de Langmuir(Universidade Federal de São Paulo, 2014-01-31) Hussein, Nadia [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Cancer is a disease characterized by the uncontrolled multiplication and spread of abnormal forms of cells. In order to treat cancer, anticancer drugs were used, which are natural or organosynthetic compounds that act against the development of cancer cells and tumor growth. In this group, we can include 1,4- naphthoquinone, which is present in various chemotherapeutics. It is a derivative of vitamin K, and a potent inhibitor of cell growth and tumor angiogenesis. Thus, this study aims to understand at the molecular level the interaction between this drug and cell membrane by means of simplified models of cell membrane (Langmuir monolayers formed by lipids). For this purpose, we performed measurements of surface tensiometry, curved surface pressure - area and infrared spectroscopy. For that, we employed the phospholipid DPPC (dipalmitoylphosphatidylcholine) for the formation of lipid monolayers (Langmuir films) which mimicked a healthy cell membrane, and DPPS (dipalmitoylphosphatidyl serine), representing cancerous membranes. Rabbit aorta endothelialcell cultures for healthy and tumorigenic cells were also employed. Phospholipids were spread on aqueous solutions, and surface pressure – area isotherms and infrared spectra were obtained. After that, different amounts of 1,4- naphthoquinone were added to the lipid monolayer and new isotherms and spectra were obtained . Similar procedures were performed with cell cultures. Three phenomena were observed due to the interaction between the monolayer and the drug: 1 ) the isotherms were shifted to smaller molecular areas, 2) 1,4- naphthoquinone increased the compressibility of the monolayer , causing a disruption in the organization of the film, which was confirmed later by infrared spectroscopy, and 3) the phase transitions has not been well defined in the surface pressure-area isotherms, suggesting a non-ideal mixture, due to interactions between the drug and the monolayer. For cell cultures, whereas minor changes were observed for cultures representing non-tumorigenic cells after the incorporation of the drug, significant changes were observed for cultures representing tumorigenic cells. Therefore, we conclude that 1,4-naphthoquinone interacts with cell membrane models represented by monolayers of DPPC, DPPS and cell cultures studied with a more expressive interaction with models of tumorigenic cells.
- ItemAcesso aberto (Open Access)Celulase e álcool desidrogenase imobilizadas em filmes de Langmuir -Blodgett para identificação de celulose e etanol no nível molecular(Universidade Federal de São Paulo, 2013-01-07) Rodrigues, Dilmer [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)In this study, we investigated at the molecular level the incorporation of cellulase and alcohol dehydrogenase (ADH) in Langmuir and Langmuir-Blodgett (LB) films of dipalmitoylphosphatidylcholine (DPPC). The mixed DPPC-enzyme films were then investigated upon contact with cellulose and ethanol. The changes at the molecular level in the properties of the films were analyzed by optical and tensiometric techniques. We aim to obtain information on the production of ethanol in a more efficient manner. The first evidence that enzymes adsorbed at the films in the lipid-water interface was through adsorption kinetic curves, wherein upon insertion of the enzyme in the aqueous subphase for monolayers of DPPC, an increase in the surface pressure values for the phospholipid matrix was observed. The second evidence was the analysis of the surface pressure-area isotherms, which showed that the presence of the enzymes caused the expansion of the lipid monolayer to higher areas. The third evidence was observed with polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), studied in Langmuir films, which revealed bands in the regions between 1500 cm-1 and 1800 cm-1, related to protein groups, namely amide II ( CN and NH bendings) and amide I (C = O stretch). In the sequence, the films were transferred to solid matrices as LB films. The PM-IRRAS analysis confirmed the successful transfer of enzyme and phospholipids. The molecular interaction between the mixed LB film (DDPC / ADH / cellulase) and cellulose was observed through PM-IRRAS since in the regions between 1500 cm-1 and 3500 cm-1, changes were observed revealing alterations in the secondary structure of the protein, related to beta-sheet, alpha-helix, beta-turn, and unordered structures. Also for the regions between 2800 cm-1 and 3500 cm-1, the symmetric and asymmetric stretches for CH in CH2 CH3 groups, as well as the stretching of amines (NH2) and OH groups could be investigated. All these factors indicate the sensitivity of the enzymes when placed in contact with cellulose dissolved in ionic liquid.
- ItemAcesso aberto (Open Access)Estudo da interação do gama-terpineol em filmes de Langmuir como modelos de membrana(Universidade Federal de São Paulo, 2021-01-29) Jaroque, Guilherme Nuñez [UNIFESP]; Caseli, Luciano [UNIFESP]; Sartorelli, Patricia [UNIFESP]; http://lattes.cnpq.br/6836392358779448; http://lattes.cnpq.br/8929162910172931; http://lattes.cnpq.br/3306052344968821This work aimed to study the interaction of γ-terpineol with lipid Langmuir monolayers, which served as a model for cell membranes to analyze the possible biological actions of the compound at the molecular level. The phospholipids used to compose the films were dipalmitoylphosphatidylcholine (DPPC), dipalmitoyl phosphatidylethanolamine (DPPE), pure or mixed with cholesterol or with bacterial peptidoglycan. The lipids were spread on the air-water interface through organic solutions assembling a Langmuir monolayer. The γ-terpineol compound was incorporated in the monolayer by co-spreading it with the lipids. The interfacial films formed at the air-water interface were compressed by movable barriers, reaching surface pressures that approached the viscoelastic and thermodynamic properties of a proteolipid bilayer. The interaction of the drug with the monolayers was analyzed using tensiometric measurements (surface pressure- area isotherms, tensiometric stability, hysteresis assays), Brewster angle microscopy, and polarization-modulation infrared reflection-adsorption spectroscopy. The physicochemical properties obtained by these measurements were analyzed, and the interactions of γ-terpineol with the lipids at the air-water interface were inferred and extrapolated for the action of the compound in related cell membranes.
- ItemAcesso aberto (Open Access)Preparação e caracterização de filmes finos de PPV contendo grupos doadores e aceptores de elétrons(Universidade Federal de São Paulo, 2014-11-18) Soares, Cecília Goncalves [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The present work was divided into two steps. The first one, the synthesis of precursor materials for polymerization by the Wessling route of poly(p-phenylene vinylene) (PPV) based materials containing acceptor (cyan) and donors (acetoxy) groups of electrons. The synthesis proved to be satisfactory, due to the obtainment pure products, confirmed by ¹H-NMR and ¹³C-NMR, and with high yields. The syntheses of the polymers were presented molecular weight lower than 12000 Da after process of purification. In the second step, the influence of the dicyano group in a copolymer of PPV, DCNPPV-PPV, was studied as its formation as in Langmuir and Langmuir-Blodgett (LB) film and its incorporation organophilic montmorillonite clay (OMMT). The Langmuir films were obtained from the pure copolymer and these films were compressed to a surface pressure of 45 mN/m without attaining the monolayer collapse. These films were transferred to solid substrates through the Langmuir-Blodgett (LB) technique, forming monolayers with few aggregates and low roughness. The incorporation of the copolymer in organophilic montmorillonite clay (OMMT) was efficient and the fluorescence analysis confirmed the incorporation of the copolymer in all proportions employed. The thermogravimetry analyses showed the thermal protection in the copolymer. In the sample containing 1% of the incorporated copolymer, a greater incorporated percentage was observed and at fluorescence analysis demonstrated a lower formation of excimers and aggregates, suggesting that the polymer chains are located in the lamellar space of the clay.
- ItemAcesso aberto (Open Access)Processamento de óxido de grafeno na forma de filmes condutores e de pontos quânticos(Universidade Federal de São Paulo, 2022-01-31) Marcellino, Gabriela Medeiros [UNIFESP]; Vieira, Nirton Cristi Silva [UNIFESP]; Gonçalves, Maraísa [UNIFESP]; http://lattes.cnpq.br/8790738991069110; http://lattes.cnpq.br/9497699863290144; http://lattes.cnpq.br/2952959130774429O óxido de grafeno (GO, graphene oxide) é um derivado de grafeno que pode ser obtido em grandes quantidades e baixo custo a partir da esfoliação química do grafite. O GO consiste em uma camada atômica de carbono com grupos funcionais oxigenados em seu plano basal em suas bordas. O GO não é um material condutor, uma vez que os grupos oxigenados quebram as duplas ligações que mantêm os átomos de carbono unidos. No entanto, a redução do GO a óxido de grafeno reduzido (rGO, reduced graphene oxide) produz um derivado do grafeno com certa estrutura π conjugada e elevada condutividade elétrica. Ainda, a quebra das folhas de GO permite a obtenção de outros derivados do grafeno, os pontos quânticos de grafeno (GQDs, graphene quantum dots). GQDs são folhas de grafeno oxidado com dimensões laterais inferiores a 100 nm e são materiais que apresentam diferentes cores de emissão. Neste TCC, o GO foi processado e utilizado para a fabricação de filmes condutores e de GQDs. No primeiro caso, o GO foi depositado sobre eletrodos interdigitados de ouro, seguido de redução eletroquímica para obtenção do rGO. Filmes com condutividade entre 50-130 Ohms foram obtidos. Além disso, os filmes condutores foram testados como transistores de efeito de campo controlados por solução (SG-FETs solutiongated field-effect transistors) apresentando transcondutância em torno de 8 a 100 µS, para elétrons e buracos, respectivamente. Os GQDs foram obtidos através do método hidrotermal na presença de H2O2 e amônia. Esses materiais apresentaram forte emissão no visível quando irradiados com luz UV. Imagens de microscopia eletrônica de transmissão não foram eveladoras do tamanho do GQDs obtidos. Em suma, a versatilidade de processamento do material GO permitiu a obtenção de diferentes materiais com possíveis aplicações em dispositivos eletrônicos e ópticos.