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ABSTRACT: Microencapsulation is used for protection and release of bioactive compounds. Combination of encapsulation methods allows the production of matrices with better technological properties compared to the application of one of the methods alone. Use of ionic gelation produces porous microparticles, and coating it with a protein, by electrostatic interaction, may contribute to a better protection of the active compound. The objective of the research was to produce alginate microparticles (AG) through ionic gelation and to coat them with soluble protein from soy protein concentrate. Two factors were studied, calcium concentration during ionic gelation (0.8, 1.6 and 2.4% w/w) and pH (3.5 and 7.0) of the protein solution for electrostatic interaction. Zeta potential (ZP) of biopolymers and microparticles were determined. Microparticles were characterized according to its morphology, average size and size distribution, as well as protein adsorption. Microparticles presented (154-334μm) multinuclear distribution of active compound, continuous and smooth surface, with a great standard deviation considering average size. The calcium concentration did not influence the protein adsorption on microparticles.The pH used in protein adsorption showed significant effect, with higher adsorption occurring at pH 3.5 (6.5 to 6.7% w/w, dry basis,db, of adsorbed protein) compared to pH 7.0 (<2.0% w/w, db, of adsorbed protein) indicating that electrostatic interaction was determinant for the protein coating. At this situation, ionic gelation microparticles and proteins presented ZP with opposite charges (pH>pKa AG<Isoelectric point, IP).
RESUMO: A microencapsulação é utilizada para a proteção de compostos bioativos e controle de sua liberação. A combinação de métodos de encapsulação permite a obtenção de matrizes com melhores propriedades tecnológicas em relação às técnicas utilizadas individualmente. Na gelificação iônica são produzidas micropartículas porosas, e o recobrimento por interação eletrostática com uma proteína permite a obtenção de micropartículas mais protetivas. O objetivo do trabalho foi produzir micropartículas de alginato (AG) através da gelificação iônica e recobri-las com proteínas solúveis de concentrado proteico de soja. Dois fatores foram estudados, o teor de cálcio utilizado na gelificação iônica (0,8,1,6 e 2,4% m/m) e o pH (3,5 e 7,0) para o recobrimento eletrostático com uma camada proteica. Os potenciais zeta (PZ) dos biopolímeros e das micropartículas foram determinados. As micropartículas foram caracterizadas quanto a morfologia, tamanho médio e sua distribuição e quanto ao teor de proteína adsorvida nas situações estudadas. As micropartículas obtidas apresentaram-se (154-334μm) com recheio distribuído de forma multinuclear, com superfície continua e visualmente lisas, porém com variação grande no tamanho médio. A variação do teor de cálcio não foi significativa na adsorção proteica. O pH utilizado na adsorção proteica foi significativo, com adsorções muito maiores em pH 3,5 (6,5 - 6,7% m/m de proteína adsorvida, base seca) comparado ao pH 7,0 (<2,0% m/m de adsorção proteica, base seca), indicando que a interação eletrostática foi determinante no recobrimento proteico. Nesta situação, micropartículas AG e a proteína apresentam PZ com cargas opostas (pH>pKa AG<ponto isoeletrico, PI).
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Aims: In the present investigation, an attempt has been made to explain lipase immobilization by adsorption on three minerals matrixes, i.e. Celite 545, Silica gel (60G) and Avicel (PH 101). Study Design: immobilization by absorption on minerals matrixes, water content by volumetric karl Fischer titration and surface potentials using a particle charge detector Mutek PCD 03 were used. Place and Duration of Study: Walloon Centre of Industrial Biology (CWBI) Unit of Bio- Industries, University of Liege, Gembloux Agro-Bio Tech, Passage des Deportes 2, B- 5030 Gembloux, Belgium between Jun 2012 and jun 2013. Methodology: A methodical order was developed whereby the influences of water content, surface potentials and pH, on immobilization by adsorption were explored. Adsorbed YLL was used to understand an interesterification reaction between rapeseed oil and milk fat in comparison with a commercial silica-granulated Thermomyces lanuginosus lipase (Lipozyme TL IM). Results: Maximum immobilization yield was obtained with Celite (70%) and the lowest with silica gel (29%). Total water content of free and immobilized lipase was determined by volumetric Karl Fischer titration. The water content of Silica gel was higher than the one of other supports. Water content of silica gel could prevent the enzyme fixation. These results could be explained by the adsorption being governed mainly by electrostatic interactions between the enzyme and matrix. This hypothesis was further reinforced by measurements of electrical potential. They showed a lowest negative potential of Silica gel after enzyme adsorption in comparison to Celite. Conclusion: From these results celite was designated as an efficient matrix to immobilize Yarrowia lipolytica lipase (YLL) by adsorption. This performed system was used to realize an interesterification reaction between rapeseed oil and milk fat in comparison with a commercial silica-granulated Thermomyces lanuginosus lipase (Lipozyme TL IM).
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OBJECTIVE: To review the development of the novel cationic nanoemulsion drug delivery system. METHODS: Making a comparison between nanoemulsion and cationic nanoemulsion on the basis of a decade of research literatures, then describing the application status and the key technical problem of this novel drug delivery system in detail. RESULTS AND CONCLUSION: Cationic nanoemusion was mainly by electrostatic and muco-adhensive approaches to promote the absorption and bioavailability of drugs. It's designed to improve the solubility of poorly soluble drugs and the permeability of nucleic and protein drugs. Nowadays, as ideal novel drug delivery system with the advantages of simple preparation and having the characters of good stability and safety, cationic nanoemusion was recently a promising alternative formulation approach for delivery of drug by oral, mucosal and transdermal drug delivery systems.
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For the evaluation on the efficacy of activated charcoal as an antidote in acute diquat poisoning, the adsorption characteristics of diquat in distilled water and in physiological saline solution were investigated.<BR>The amount of diquat adsorbed onto activated charcoal in physiological saline solution was larger than that in distilled water. The enhancing effect of sodium chloride on diquat removal by activated charcoal was observed.<BR>The adsorption rate of diquat onto activated charcoal was also enhanced by the addition of saline. The correlations between the adsorptivity for diquat and properties of activated charcoal were not significant.<BR>These results suggest that the increase of adsorptivity of activated charcoal for diquat might be due to the increase in electrostatic interaction between the surface on which an electrical double layer was formed by saline and diquat.