Propriedades estáticas e dinâmicas dos polímeros naturais xantana, hialuronato de sódio e metilcelulose por espalhamento de luz e raio-X a baixos ângulos

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Curso de Pós-Graduação em QuímicaEstudou-se neste trabalho as propriedades estáticas e dinâmicas dos polímeros naturais xantana (XT) , hialuronato de sódio (Na-Hy) e metilcelulose (MC) utilizando-se as técnicas de espalhamento de luz e raio-x a baixos ângulos. A discussão das propriedades das soluções dos polieletrólitos (XT e Na-Hy) e a transição sol-gel do polímero neutro (MC) envolveu importantes aspectos relacionadas com a estrutura, interações e dinâmica nestes polissacarídeos. Para as soluções dos polieletrólitos foram avaliados a influência da concentração do polímero, força iônica (adição de sal ou surfactante(C10TAB)), temperatura e velocidade de cisalhamento sobre as propriedades de espalhamento. Na transição sol-gel da MC foram avaliados o mecanismo de separação de fases, a dependência da cinética de separação de fase com a temperatura e a influência da adição do eletrólito NaCl sobre a temperatura de gelificação

Curcumin and Quercetin-Loaded Nanoemulsions: Physicochemical Compatibility Study and Validation of a Simultaneous Quantification Method

Biphasic oil/water nanoemulsions have been proposed as delivery systems for the intranasal administration of curcumin (CUR) and quercetin (QU), due to their high drug entrapment efficiency, the possibility of simultaneous drug administration and protection of the encapsulated compounds from degradation. To better understand the physicochemical and biological performance of the selected formulation simultaneously co-encapsulating CUR and QU, a stability test of the compound mixture was firstly carried out using X-ray powder diffraction and thermal analyses, such as differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The determination and quantification of the encapsulated active compounds were then carried out being an essential parameter for the development of innovative nanomedicines. Thus, a new HPLC-UV/Vis method for the simultaneous determination of CUR and QU in the nanoemulsions was developed and validated. The X-ray diffraction analyses demonstrated that no interaction between the mixture of active ingredients, if any, is strong enough to take place in the solid state. Moreover, the thermal analysis demonstrated that the CUR and QU are stable in the nanoemulsion production temperature range. The proposed analytical method for the simultaneous quantification of the two actives was selective and linear for both compounds in the range of 0.5-12.5 µg/mL (R2 > 0.9997), precise (RSD below 3%), robust and accurate (recovery 100 ± 5 %). The method was validated in accordance with ICH Q2 R1 "Validation of Analytical Procedures" and CDER-FDA "Validation of chromatographic methods" guideline. Furthermore, the low limit of detection (LOD 0.005 µg/mL for CUR and 0.14 µg/mL for QU) and the low limit of quantification (LOQ 0.017 µg/mL for CUR and 0.48 µg/mL for QU) of the method were suitable for the application to drug release and permeation studies planned for the development of the nanoemulsions. The method was then applied for the determination of nanoemulsions CUR and QU encapsulation efficiencies (> 99%), as well as for the stability studies of the two compounds in simulated biological fluids over time. The proposed method represents, to our knowledge, the only method for the simultaneous quantification of CUR and QU in nanoemulsions

Design and Characterization of Maltoheptaose-b-Polystyrene Nanoparticles, as a Potential New Nanocarrier for Oral Delivery of Tamoxifen

Tamoxifen citrate (TMC), a non-steroidal antiestrogen drug used for the treatment of breast cancer, was loaded in a block copolymer of maltoheptaose-b-polystyrene (MH-b-PS) nanoparticles, a potential drug delivery system to optimize oral chemotherapy. The nanoparticles were obtained from self-assembly of MH-b-PS using the standard and reverse nanoprecipitation methods. The MH-b-PS@TMC nanoparticles were characterized by their physicochemical properties, morphology, drug loading and encapsulation efficiency, and release kinetic profile in simulated intestinal fluid (pH 7.4). Finally, their cytotoxicity towards the human breast carcinoma MCF-7 cell line was assessed. The standard nanoprecipitation method proved to be more efficient than reverse nanoprecipitation to produce nanoparticles with small size and narrow particle size distribution. Moreover, tamoxifen-loaded nanoparticles displayed spherical morphology, a positive zeta potential and high drug content (238.6 ± 6.8 µg mL−1) and encapsulation efficiency (80.9 ± 0.4 %). In vitro drug release kinetics showed a burst release at early time points, followed by a sustained release profile controlled by diffusion. MH-b-PS@TMC nanoparticles showed higher cytotoxicity towards MCF-7 cells than free tamoxifen citrate, confirming their effectiveness as a delivery system for administration of lipophilic anticancer drug

Poder Calorífico da Casca de Arroz, Caroço de Pêssego, Serragem de Eucalipto e de seus Produtos de Pirólise

The Higher Heating Value (HHV) of rice husks, peach stones andeucalyptus sawdust was determined, as well as of the resulting bio-oils andresidual chars from low temperature conversion process. Products yields forbio oils varied from 16 to 26%, and for solid residue, from 38 to 48%. HHV of3,900, 2,600 and 4,100 cal/g were measured for rice husks biomass, its residualchar and bio-oil; 4,100, 5,800 and 4,000 cal/g, for eucalyptus sawdust, its charand bio oil; 3.,400, 3,200 e 3,900 cal/g, for peach stones, its char and bio oil,respectively. These values show that biomasses and pyrolysis products canbe considered as renewable energy sources, clean and neutral to global warming.Determinou-se o poder calorífico superior (PCS) das biomassas:casca de arroz, caroço de pêssego, serragem de eucalipto, e dos bioóleos eresíduos carbonosos correspondentes, obtidos por conversão térmica a baixatemperatura. Rendimentos de bioóleo entre 16% e 26%, e, de resíduo carbonoso,entre 38% e 48%, foram obtidos na pirólise. Valores de Poder Calorífico de3.900, 2.600 e 4.100 cal/g foram medidos para a casca de arroz, seu carvão e óleode pirólise; 4.100, 5.800 e 4.000 cal/g, para serragem de eucalipto, seu carvão eóleo de pirólise; 3.400, 3.200 e 3.900 cal/g, para caroço de pêssego, seu carvãoe bioóleo, respectivamente. Estes valores demonstram que as biomassas e osseus produtos de pirólise podem ser considerados fontes renováveis de energia,limpas e neutras quanto ao fenômeno de aquecimento global.Palavras chave: biomassa, pirólise, poder calorífico superior

Estudo do comportamento de memoria de materiais polimericos em estado de nao-equilibrio termodinamico

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Synthesis and characterization of [Cd8Cl2Se(SePh)12(PCy3)2]•2.5CH3OH

Neste artigo estamos apresentando a síntese do composto [Cd8Cl2(μ4-Se)(SePh)12(PCy3)2]·2.5CH3OH pela reação de Cd(SePh)2 com CdCl2 e triciclohexilfosfina em metanol em um reator de aço inoxidável sob condições solvotérmicas a 130 °C. Esse composto corresponde ao último resultado de uma série sistemática de reações e visando ao crescimento de clusters moleculares a partir de Cd(SePh)2 como reagente de partida. A importância desta síntese não está baseada somente nas propriedades do produto preparado, mas também no seu possível uso, por exemplo, no desenvolvimento de novas metodologias via estratégias “bottom up” para a obtenção de clusters a partir de uma mesma classe de reagentes - M(ER)2 (M = metal, E = calcogênio, R  =   alquil ou aril). O composto apresentado neste artigo foi caracterizado por difração de raios X em monocristal, análise elementar, análise termogravimétrica e espectroscopia no UV-Vis. Estes últimos resultados foram correlacionados com dados calculados por DFT, teoria do funcional de densidade.In this article we present the synthesis of the compound [Cd8Cl2Se(SePh)12(PCy3)2]·2.5CH3OH by the reaction of Cd(SePh)2 with CdCl2 and PCy3 in methanol in a stainless steel sealed reactor under solvothermal conditions at 130 °C. This compound represents the latest result of our systematic work on the growth of molecular clusters from Cd(SePh)2 as starting material. Their importance is based not only on the properties of the new compounds, but also by their possible use, for example, in the development of new methods via a ‘‘bottom up” strategy to obtain different clusters from single components like M(ER)2 (M = metal, E = chalcogen, R = alkyl or aryl). The title compound was characterized by single crystal X-ray diffractometry, elemental analysis, thermogravimetrical analysis and the UV-Vis spectroscopy. These results were correlated with data calculated by DFT, density functional theory