Página 1 dos resultados de 227 itens digitais encontrados em 0.005 segundos

Síntese e caracterização de nanopartículas núcleo-casca de poliestireno e polimetacrilato de metila obtidas por polimerização em emulsão sem emulsificante e fotoiniciada.; Synthesis and characterization of core-shell nanoparticles of polystyrene and poly(methyl metacrylate) obtained by emulsifier-free emulsion polymerization and photopolymerization.

Carranza Oropeza, María Verónica
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/09/2011 PT
Relevância na Pesquisa
37.35%
O objetivo do trabalho foi sintetizar e caracterizar nanopartículas de poliestireno e polimetacrilato de metila com morfologia núcleo-casca obtidas através da polimerização em emulsão sem emulsificante em dois estágios e através da fotopolimerização. Nos experimentos avaliou-se a influência de diferentes condições operacionais baseadas em fatores cinéticos sobre os dois estágios da polimerização. As condições avaliadas para o primeiro estágio de preparação de núcleos foram: a temperatura do processo, a concentração de iniciador e de monômero, e o efeito de agentes modificadores de superfície (sal, co-monômero e reticulante). Para o segundo estágio de formação da casca as condições avaliadas foram: a concentração e o regime de alimentação de monômero. Os resultados experimentais mostraram que uma relação de co-monômero e reticulante é a melhor alternativa para preparar núcleos estáveis e de diâmetros pequenos. Assim, o revestimento uniforme dos núcleos é obtido no segundo estágio e com isso a morfologia núcleo-casca em equilíbrio é alcançada. Dois sistemas experimentais (reator convencional e reator fotoquímico) foram propostos e avaliados na sua eficiência para obter partículas com este tipo de morfologia no segundo estágio (formação do revestimento). As diversas técnicas de caracterização indicaram a formação de morfologia núcleo-casca na maioria dos casos estudados para os dois sistemas propostos. Por sua vez...

Emulsifier in broiler diets containing different fat sources

Guerreiro Neto, AC; Pezzato, AC; Sartori, JR; Mori, C; Cruz, VC; Fascina, VB; Pinheiro, DF; Madeira, LA; Gonçalvez, JC
Fonte: Fundação APINCO de Ciência e Tecnologia Avícolas Publicador: Fundação APINCO de Ciência e Tecnologia Avícolas
Tipo: Artigo de Revista Científica Formato: 119-125
ENG
Relevância na Pesquisa
27.65%
This present study aimed at evaluating the effect of the addition of an emulsifier to diets containing soybean oil, poultry fat or their blend, on the performance, carcass traits, serum lipid levels, pancreatic lipase concentration and nutrient digestibility of broilers. A randomized block design was applied using a 3 x 2 factorial arrangement, with three fat sources (soybean oil, poultry fat, and a blend of 50% soybean oil and 50% poultry fat) and the addition or not of an emulsifier. In experiment I, broiler performance, carcass traits, serum cholesterol, HDL, and triglyceride levels, and pancreatic lipase activity in 42-day-old broilers were evaluated. In experiment II, dry matter (DM), ether extract (EE), crude protein (CP) and crude fiber (CF) coefficients of digestibility were analyzed. Broilers fed the diet containing soybean oil and emulsifier presented higher body weight, weight gain and better feed conversion ratio. When birds were fed poultry fat and the fat blend (soybean oil and poultry fat) and the emulsifier was added to the diets, pancreatic lipase concentration increased. It was concluded that the use of soybean oil, poultry fat and their blend does no in the diet does not influence the performance, carcass traits...

Effect of Various Thickening Agents on the Rheological Properties of Oil-in-Water Emulsions Containing Nonionic Emulsifier

Isaac, V. L. B.; Cefali, L. C.; Chiari, B. G.; Almeida, M. G. J.; Ribeiro, H. M.; Corrêa, M. A.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 880-885
ENG
Relevância na Pesquisa
37.35%
The knowledge of rheological characteristics can indicate the emulsions properties, thus, nowadays rheology is used in the cosmetic and pharmaceutical industries, even to study the influence of rheological additives on them. Ten emulsions were prepared with 5% and 10% of nonionic emulsifier. Two of them were used as controls while in the others were added thickening agents. Rheological analyses were performed. The results showed that all emulsions are non-Newtonian, thixotropics and viscoelastics fluids. The thickening agents could modify the rheological characteristics of the emulsions and knowing the influence of them is easy to adopt one to reach the desirable performance. © 2013 Copyright Taylor and Francis Group, LLC.

Desenvolvimento de pastas alimenticias instantaneas por processo de extrusão termoplastica : influencia do tipo de trigo, teor de emulsificantes e parametros do processo na qualidade do produto.; Development of instantaneous pastas for thermoplastic extrusion process: influence of the type of wheat, text of emulsifier and parameters of the process in the product quality.

Matheus Depieri
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/04/2004 PT
Relevância na Pesquisa
27.65%
O presente trabalho analisou a produção de pastas instantâneas feitas a partir de dois tipos de matérias-primas, a farinha de trigo comum e a semolina de trigo durum, utilizando o processo de extrusão termoplástica. O objetivo principal do trabalho foi comparar a qualidade dos dois tipos de pastas obtidos, já que pelo processo convencional de produção de massas alimentícias, a matéria-prima mais usada e que garante melhor qualidade às pastas é a semolina de trigo durum, que, por outro lado, apresenta um maior custo. Procurou-se, através do processo de extrusão, obter produtos de características semelhantes, mesmo usando uma matéria-prima de qualidade inferior e custo mais baixo, que é o caso da farinha de trigo comum. Para isso foi utilizado um extrusor termoplástico de rosca simples Brabender mod. 1014/2, seguindo um planejamento experimental do tipo composto central rotacional com 3 variáveis independentes, a temperatura na 2ª zona do extrusor (x1), umidade da mistura inicial (x2) e teor de emulsificante na mistura inicial (x3). Foram analisadas, além da composição centesimal e características reológicas das matérias-primas, as seguintes respostas para as pastas instantâneas obtidas: umidade, cor, tempo ótimo de cozimento...

Estudo da sintese de esteres de cera utilizando lipases em diferentes sistemas de reação; Study on the synthesis of wax esters with lipases in different reaction systems t

Danielle Branta Lopes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/03/2009 PT
Relevância na Pesquisa
27.35%
O aumento da demanda por esteres obtidos naturalmente ou por processos biotecnologicos, para aplicacoes como aditivos em alimentos, cosmeticos, industrias farmaceuticas e de lubrificantes, faz necessario o desenvolvimento de catalisadores altamente especificos. Por esta razao, o uso de enzimas como catalisadores para a sintese de esteres de alto valor agregado vem sofrendo um rapido desenvolvimento, por proporcionar a possibilidade de obtencao de um produto atraves de um processo biologico. Embora destinada pela natureza para realizar a hidrolise de lipideos, lipases (E.C. 3.1.1.3) podem, sob condicoes apropriadas de reacao, promover a formacao de esteres atraves de reacoes de acidos e álcoois (esterificacao). Comparadas com processos quimicos ja realizados em uma escala industrial, reacoes enzimaticas ocorrem sob condicoes brandas (e ecologicamente mais favoraveis) apesar de poderem ser mais lentas. A grande vantagem e a especificidade apresentada pelas enzimas, que permite a formacao de derivados lipidicos, os quais nao sao facilmente preparados por processos laboratoriais convencionais. Neste trabalho, foi avaliado o desempenho de lipases microbianas e vegetais, nao-comerciais, e comparadas a uma lipase comercial, na síntese de esteres com possiveis propriedades emulsificantes...

Efeito da aidição de emulsificantes na cristalização de gorduras baixo trans para recheio de biscoito; Emulsifier addition effects on low trans biscuit fat filling crystalization

Fernanda Zaccarelli Davoli
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/08/2010 PT
Relevância na Pesquisa
37.53%
As comprovações científicas que demonstram os danos causados à saúde pelo consumo de ácidos graxos trans, aliadas às novas legislações que restringem a quantidade de ácidos graxos trans ou determinam a necessidade de suas quantidades serem especificadas nas tabelas nutricionais dos rótulos dos alimentos, tornaram a interesterificação e as técnicas de misturas de diferentes fontes de gorduras, ferramentas fundamentais para o desenvolvimento de gorduras e alimentos livres de ácidos graxos trans. A indústria de alimentos precisa de conhecimento sobre a funcionalidade e aplicabilidade de gorduras formuladas com baixo conteúdo de ácidos graxos trans e sobre o efeito de aditivos, como os emulsificantes, nas suas características físico-químicas. Neste trabalho, três gorduras comerciais com baixo conteúdo de ácidos graxos trans (duas para recheio de biscoito tipo wafer e uma para recheio de biscoito tipo sanduíche) foram aditivadas com cinco emulsificantes diferentes, a uma dosagem constante de 3%. Os emulsificantes utilizados foram 5 versões de mono e mono-diglicerídios saturados, que diferiam com relação à matéria-prima usada na sua produção e o teor de monoglicerídio contido no produto. As características físico-químicas determinadas nas gorduras foram: perfil de sólidos...

Isolamento e caracterização de composto ativo de superfície produzido por gordonia amicalis; Isolation and characterization of a SAC produced by Gordonia amicalis

Fernanda Franzoni Pescumo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/02/2013 PT
Relevância na Pesquisa
27.05%
Biossurfactantes e bioemulsificantes são compostos ativos de superfícies (CAS) produzidos por micro-organismos. Desempenham várias funções biológicas, e sua característica anfifílica, juntamente com baixa toxicidade, biodegradabilidade e resistência a extremos de pH, temperatura e salinidade, tem despertado o interesse para a aplicação dessas moléculas em processos biotecnológicos. Porém, o alto custo aliado à baixa produção ainda são impedimentos para a utilização em larga escala. Os desafios para se implementar a produção são: desenvolvimento de estratégias para tornar a produção economicamente viável e o isolamento de moléculas e microorganismos mais eficientes. Neste trabalho, foi estudada a produção, isolamento, extração e caracterização de um CAS por Gordonia amicalis. O micro-organismo foi cultivado em meio GYP (glucose, extracto de levedura, peptona) por 7 dias, e a extração foi feita por precipitação com sulfato de amônio, que resultou em uma concentração de 0,5 g/L do extrato bruto em meio líquido. O CAS não reduziu significativamente a tensão superficial do meio GYP, e apresentou um balanço hidrofílico-lipofílico (HBL) de caráter lipofílico, apresentando mais emulsões do tipo água em óleo (A/O) do que óleo em água (O/A). A molécula apresentou estabilidade a temperaturas de 25ºC a 100ºC...

Emulsifier in broiler diets containing different fat sources

Guerreiro Neto,AC; Pezzato,AC; Sartori,JR; Mori,C; Cruz,VC; Fascina,VB; Pinheiro,DF; Madeira,LA; Gonçalvez,JC
Fonte: Fundação APINCO de Ciência e Tecnologia Avícolas Publicador: Fundação APINCO de Ciência e Tecnologia Avícolas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 EN
Relevância na Pesquisa
27.65%
This present study aimed at evaluating the effect of the addition of an emulsifier to diets containing soybean oil, poultry fat or their blend, on the performance, carcass traits, serum lipid levels, pancreatic lipase concentration and nutrient digestibility of broilers. A randomized block design was applied using a 3 x 2 factorial arrangement, with three fat sources (soybean oil, poultry fat, and a blend of 50% soybean oil and 50% poultry fat) and the addition or not of an emulsifier. In experiment I, broiler performance, carcass traits, serum cholesterol, HDL, and triglyceride levels, and pancreatic lipase activity in 42-day-old broilers were evaluated. In experiment II, dry matter (DM), ether extract (EE), crude protein (CP) and crude fiber (CF) coefficients of digestibility were analyzed. Broilers fed the diet containing soybean oil and emulsifier presented higher body weight, weight gain and better feed conversion ratio. When birds were fed poultry fat and the fat blend (soybean oil and poultry fat) and the emulsifier was added to the diets, pancreatic lipase concentration increased. It was concluded that the use of soybean oil, poultry fat and their blend does no in the diet does not influence the performance, carcass traits...

Effect on the enzymatic hydrolysis of lipids from dairy wastewater by replacing Gum Arabic emulsifier for sodium chloride

Mendes,Adriano Aguiar; Castro,Heizir Ferreira de
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
Relevância na Pesquisa
27.05%
The objective of this work was to evaluate the replacement of Gum Arabic for sodium chloride to reduce fat and organic contents in dairy wastewater using two low cost commercially available lipase preparations from animal source (Kin Master - LKM and Nuclear- LNU). The best performance was achieved when lipase Nuclear (LNU) was used as catalyst. In addition, this lipase preparation has also lower cost, which makes its use a quite promising technique for reduction of suspended solids as proteins and lipids contents found in wastewater generated by dairy industries.

Evaluation of emulsifier stability of biosurfactant produced by Saccharomyces lipolytica CCT-0913

Lima,Álvaro Silva; Alegre,Ranulfo Monte
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2009 EN
Relevância na Pesquisa
37.35%
Surface-active compounds of biological origin are widely used for many industries (cosmetic, food, petrochemical). The Saccharomyces lipolytica CCT-0913 was able to grow and produce a biosurfactant on 5% (v/v) diesel-oil at pH 5.0 and 32ºC. The cell-free broth emulsified and stabilized the oil-in-water emulsion through a first order kinetics. The results showed that the initial pH value and temperature influenced the emulsifier stability (ES), which was the time when oil was separated. The biosurfactant presented different stabilization properties for vegetable and mineral oil in water solution, despite the highest values of the ES occurring with vegetable oil. The biosurfactant presented smallest ES when compared to commercial surfactants; however, this biosurfactant was not purified.

Influence of emulsifier content on properties and durability of cutting fluids

Rao,D. Nageswara; Srikant,R. R.; Rao,Ch. Srinivasa
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 EN
Relevância na Pesquisa
37.53%
The use of cutting fluids is well recognized for several years. To cater the needs of state- of- art machining processes, several fluid formulations are available in the present day market. Of such available fluids, water-soluble fluids are dominant. Though, the need of cutting fluids is explored, the functionality of different ingredients of the fluid is not much investigated. The present work is an attempt to study the role of emulsifier on the properties and performance of cutting fluid. In the present part of the paper, estimation of basic properties and microbial contamination of the fluids with varying emulsifier contents is dealt.

Mathematical Modeling of the Influence of Emulsifier Content on Performance of Cutting Fluids

Srikant,Revuru Revuru; Rao,Damera Nageswara; Rao,Chalamalasetti Srinivasa; Subrahmanyam,Mendu Siva
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2008 EN
Relevância na Pesquisa
37.53%
The present work is an attempt to study the role of emulsifier on the effectiveness of cutting fluids. Cutting tests have been carried out and influence on different parameters is estimated. A mathematical model is proposed to estimate the influences of emulsifier content on tool wear.

Emulsifier of Arthrobacter RAG-1: isolation and emulsifying properties.

Rosenberg, E; Zuckerberg, A; Rubinovitz, C; Gutnick, D L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1979 EN
Relevância na Pesquisa
27.74%
The oil-degrading Arthrobacter sp. RAG-1 produced an extracellular nondialyzable emulsifying agent when grown on hexadecane, ethanol, or acetate medium. The emulsifier was prepared by two procedures: (i) heptane extraction of the cell-free culture medium and (ii) precipitation with ammonium sulfate. A convenient assay was developed for measurement of emulsifier concentrations between 3 and 75 micrograms/ml. The rate of emulsion fromation was proportional to both hydrocarbon and emulsifier concentrations. Above pH 6, activity was dependent upon divalent cations; half-maximum activity was obtained in the presence of 1.5 mM Mg2+. With a ratio of gas oil to emulsifier of 50, stable emulsions were formed with average droplet sizes of less than 1 micron. Emulsifier production was parallel to growth on either hydrocarbon or nonhydrocarbon substrates during the exponential phase; however, production continued after growth ceased.

Emulsifier of Arthrobacter RAG-1: Chemical and Physical Properties

Zuckerberg, A.; Diver, A.; Peeri, Z.; Gutnick, D. L.; Rosenberg, E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1979 EN
Relevância na Pesquisa
27.05%
The extracellular emulsifier of Arthrobacter RAG-1 was deproteinized by hot phenol treatment and purified by fractional precipitation with (NH4)2SO4. The active fraction, precipitating between 30 and 35% saturation [EF-RAG(UET) WA], appeared to be homogeneous by immunodiffusion and sedimentation analysis. EF-RAG(UET) WA had an intrinsic viscosity of 750 cm3/g, a sedimentation constant of 6.06S, a diffusion constant of 5.25 × 10−8 cm2 s−1, and a partial molar volume of 0.712 cm3 g−1. From these data a weight average molecular weight of 9.76 × 105 and a viscosity average molecular weight of 9.88 × 105 were calculated. EF-RAG(UET)WA contained 46.7% C, 7.01% H, and 6.06% N. Titration of the nonreducing polymer gave a single inflection point (pK′ = 3.05), corresponding to 1.5 μmol of carboxyl groups per mg. Direct estimation of O-ester and hexose content of the highly acidic polymer yielded 0.65 and 0.29 μmol/mg, respectively. Mild alkaline hydrolysis released fatty acids with an average molecular weight of about 231. Strong acid hydrolysis of EF-RAG(UET)WA yielded d-glucose (minor), d-galactosamine (major), and an unidentified amino uronic acid (major).

Effects of Supplemental Exogenous Emulsifier on Performance, Nutrient Metabolism, and Serum Lipid Profile in Broiler Chickens

Roy, Amitava; Haldar, Sudipto; Mondal, Souvik; Ghosh, Tapan Kumar
Fonte: SAGE-Hindawi Access to Research Publicador: SAGE-Hindawi Access to Research
Tipo: Artigo de Revista Científica
Publicado em 05/07/2010 EN
Relevância na Pesquisa
27.65%
The effects of an exogenous emulsifier, glyceryl polyethylene glycol ricinoleate, on performance and carcass traits of broiler chickens were assessed. The emulsifier was added to the diet at dose rates of 0 (control), 1 (E1) and 2 (E2) % of added fat (saturated palm oil). Live weight gain (P < .07) and feed conversion ratio (P < .05) in 39 days were higher in the E1 dietary group. Gain: ME intake and gain: protein intake during the grower phase improved quadratically (P < .05). Gross carcass traits were not affected. Body fat content and fat accretion increased (P < .05) and liver fat content decreased (P < .05) linearly with the level of emulsifier in diet. Fat excretion decreased (P < .001) leading to increased ileal fat digestibility (P < .06) in the E1 group (quadratic response). Metabolizable intake of N (P < .1) and fat (P < .05) increased quadratically due to supplementation of emulsifier in diet. Metabolism of trace elements and serum lipid profiles were not affected. The study revealed that supplementation of exogenous emulsifiers in diets containing moderate quantities of added vegetable fats may substantially improve broiler performance.

Oil-in-water emulsion lotion providing controlled release using 2-methacryloyloxyethyl phosphorylcholine n-butyl methacrylate copolymer as emulsifier

Ishikawa, Akiko; Fujii, Makiko; Morimoto, Kumi; Yamada, Tomomi; Koizumi, Naoya; Kondoh, Masuo; Watanabe, Yoshiteru
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 01/02/2012 EN
Relevância na Pesquisa
27.05%
Lotion is a useful vehicle for active ingredients used to treat skin disease because it can be applied to the scalp, can cover large areas of skin, and it is easy to spread due to low viscosity. An emulsion lotion (EL) containing 2-methacryloyloxyethyl phosphorylcholine n-butyl methacrylate copolymer (PMB) as an emulsifier that provides controlled-release was developed. Diphenhydramine (DPH) was used as a model drug. Formulation with 5% DPH, 5% soybean oil, and 4% PMB in water was emulsified using a high-pressure homogenizer. Polysorbate 80 (TO) was used instead of PMB for comparison. They were applied in vitro to Yucatan micropig intact or stripped skin at a practical dose (2 μL/cm2). For stripped skin, penetration of DPH from 4% PMB EL was slower than that from 1% TO EL; results for intact skin were similar. The same phenomenon was observed with application to rabbit skin in vivo. When 4% PMB EL dried on the skin, it made a thin film matrix incorporating the oil phase, which controlled the release of DPH. The release rate could be controlled by the ratio of oil phase to PMB. The EL with PMB shows promise as a vehicle for long-acting treatment of skin diseases.

Influence of α-Helices on the emulsifying properties of proteins; Influence of alpha-helices on the emulsifying properties of proteins

Poon, S.; Clarke, A.; Currie, G.; Schultz, C.
Fonte: Japan Soc Biosci Biotechn Agrochem Publicador: Japan Soc Biosci Biotechn Agrochem
Tipo: Artigo de Revista Científica
Publicado em //2001 EN
Relevância na Pesquisa
27.05%
A peptide derived from apomyoglobin by cyanogen bromide cleavage was found to be an active emulsifier. This molecule, peptide 1-55, has two potential amphipathic α-helices and a hydrophilic C-terminal domain. The importance of this molecule was investigated by testing the products of gene constructs based on the sequence of peptide 1-55, but lacking one of the three domains. The emulsifying activity of the peptides lacking either of the α-helices was correlated with the hydrophobic moments of their respective helices. The hydrophobic moment is a measure of the amphipathicity of α-helices; a hydrophobic moment analysis of other emulsifying peptides supports the hypothesis that a high hydrophobic moment contributes to good emulsifying properties in a molecule which contains α-helices.

Facile size-controllable syntheses of highly monodisperse polystyrene nano- and microspheres by polyvinylpyrrolidone-mediated emulsifier-free emulsion polymerization

Du, X.; He, J.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
27.05%
Abstract not available; Xin Du, Junhui He

Einfluss von Cyclodextrinen auf HPMC-stabilisierte Öl-in-Wasser-Emulsionen; Influence of cyclodextrins on oil-in-water emulsions containing hypromellose (HPMC) as a polymeric emulsifier

Rother, Patrick
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
27.35%
Ziel der vorliegenden Arbeit war es, in systematischen Untersuchungen abzuklären, inwiefern O/W-Emulsionen, die mit HPMC als Polymeremulgator stabilisiert werden, von der Zugabe von Cyclodextrinen, einer Gruppe bekannter pharmazeutischer Komplexbildner, profitieren können. Es sollte geklärt werden, welche Eigenschaften der Emulsionen durch den Komplexbildner beeinflusst werden, und zwar sowohl was das Grenzflächenverhalten von Polymer und Komplexen als auch was die galenischen Eigenschaften anbetrifft. Um die Mechanismen, aufgrund derer der Komplexbildner die Emulsionsstabilität beeinflussen kann, zu verstehen, ist die Untersuchung seines Verhaltens an der Phasengrenzfläche unerlässlich. Sie kann jedoch aus praktischen Gründen nicht in den fertigen Emulsionen stattfinden, sondern erfolgt vielmehr an Modellgrenzflächen. An diesen wurde die dynamische Grenzflächenspannung gemessen sowie die Grenzflächendilatationsrheologie charakterisiert. Zunächst wurde mit Hilfe eines Screening-Verfahrens ermittelt, welche Ölphase für die Emulsionsherstellung am geeignetsten ist. Dabei ergab sich ein starker Einfluss der Ölphase auf das Grenzflächenverhalten der gebildeten Cyclodextrin-Lipid-Komplexe. Z.B. ist 2-Ethylhexylstearat als Ölphase offenbar geeignet...

Vitamin E TPGS Used as Emulsifier in the Preparation of Nanoparticulate Systems

Bernabeu, Ezequiel Adrian; Chiappetta, Diego Andrés
Fonte: American Scientific Publishers Publicador: American Scientific Publishers
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
27.35%
In recent years, nanoparticulate systems have matured from simple devices to multifunctional and more complex systems. They are biodegradable, stable in blood, non-toxic, and non immunogenic construct, capable of delivering drugs in a specific site, thereby improving efficacy. Their capabilities as drug delivery system and the interaction with the biological cells in the target tissue are dependent on their physicochemical properties such as particles size, size distribution, surface charge and morphology. Polymeric nanoparticles are usually produced by two classical methods: nanoprecipitation and emulsion-solvent evaporation technique. In such process, a number of preparation parameters can affect the nature of the nanoparticles as: drug, polymer concentration, temperature, solvent volume, aqueous:organic phase ratio, type and concentration of emulsifier and so forth. One of the most important formulation parameters involves the emulsifier, which is necessary as surfactant stabilizer in the process to form nanoparticles. D-α-tocopheryl polyethylene glycol (PEG) 1000 succinate (TPGS) is a water soluble derivate of natural source vitamin E. It is amphipathic and hydrophilic, exhibiting the characteristics of a typical surface-active agent. This review summarizes recently available information regarding the emulsifying effects of TPGS on the preparation...