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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Polyelectrolyte core/hydrophobic shell polymer particles by double emulsion templating polymerisation for environmental applications

Menzel, Cristian January 2015 (has links)
Herein two novel synthetic strategies for the synthesis of sub-millimetre sized core–shell particles comprising a polyelectrolyte core and a porous hydrophobic shell are presented. In the first method, a water-in-oil-in-water (W/O/W) double-emulsion was used as a template for the simultaneous polymerisation of both the internal aqueous and the intermediate oil phases, via suspension polymerisation, leading to the formation of a cross-linked poly(acrylic acid-co-bisacrylamide) core contained in a porous poly(4-tert-butylstyrene-co-divinylbenzene) shell. It was found that the formation of core–shell morphology was favoured by the effect of acrylic acid which was responsible for the selective destabilization of the internal aqueous/oil (W/O) interface. It was found that rapid internal phase coarsening promoted the formation of single-core structures. A rapid gel-point of the oil phase, on the other hand, reduced the internal aqueous phase diffusion towards the external phase. The detrimental effect over internal emulsion stability was replicated using ethanol, 2-propanol, n-butanol and propionic acid which were used as a co-solvent in the internal aqueous phase to promote core/shell morphology formation. The second method involved the use of a flow-focusing device for the formation of monodisperse W/O/W emulsion droplets which were photo-polymerised. Anionic poly(sodium acrylate), poly(sodium vinyl sulfonate), and cationic poly(3-acrylamidopropyl)trimethylammonium chloride) hydrogels were encapsulated within a porous poly(trimethylolpropane triacrylate-co-methyl methacrylate) shell. Control over both particle diameter and shell thickness was achieved by tuning the flow rates of the different phases. The use of these novel hydrogel core/shell particles as novel material for environmental applications, including the scavenging of radionuclides, was investigated. It was found that hydrophilic substances including dyes and metal ions were rapidly adsorbed and encapsulated within the core region after diffusing through the permeable porous shell. Part of the results obtained in this work have been published in the article J. Mater. Chem. A, 2013, 1, 12553-12559.
2

Primena protein-polimer interakcije za formiranje mikrokapsula sa kontrolisanim otpuštanjem aktivne supstance / Application of the protein-polymer interaction for the formation of microcapsules with controlled release of the active substance

Fraj Jadranka 25 November 2016 (has links)
<p>Mikrokapsule, kao nosači aktivnih supstanci, imaju sve veću primenu u različitim granama industrije, naročito prehrambene i farmaceutske. Inkorporiranje biolo&scaron;ki aktivnih supstanci unutar mikrokapsula omogućava maskiranje neprijatnih mirisa i ukusa, za&scaron;titu osetljivih i lako isparljivih komponenata.<br />Cilj ove doktorske disertacije je dobijanje mikrokapsula za istovremeno inkorporiranje hidrosolubilnih i liposolubilnih aktivnih materija, radi njihove za&scaron;tite i kontrolisanog otpu&scaron;tanja. Mikrokapsule su formirane iz duplih emulzija tipa voda-ulje-voda (V/U/V) metodom koacervacije, odnosno deponovanjem koacervata, koji nastaje u sistemu dva suprotno naelektrisana proteina, želatina i natrijum kazeinata (NaKN), na granicu faza ulje/voda. Kao model supstance za hidrosolubilne i liposolubilne biolo&scaron;ki aktivne materije, kori&scaron;ćeni su vitamini C i E.<br />Najpre su detaljno ispitane interakcije u sistemu želatin/NaKN primenom različitih metoda (merenje zeta potencijala, tenziometrija, viskozimetrija, reolo&scaron;ka ispitivanja). Na osnovu ovih rezultata definisane su promene, kako na granici faza, tako i unutar rastvora, kao i mehanizama formiranja koacervata između ova dva suprotno naelektrisana proteina. Utvrđeno je da se pri masenom odnosu želatin:NaKN od 2:1 dolazi do formiranja nerastvornog koacervata. Ispitan je uticaj interakcija u ovom sistemu na osobine duplih, V/U/V emulzija dobijenih emulgovanjem primarnih voda/ulje (V/U) emulzija u sme&scaron;i želatin/NaKN, pri njihovim odabranim masenim odnosima i zaključeno je da interakcija između proteina u kontinualnoj fazi utiče na<br />osobine emulzija.<br />S obzirom da je prvi korak ka dobijanju stabilne V/U/V emulzije, dobijanje stabilne primarne V/U emulzije, ispitana je mogućnost primene lipofilnih emulgatora, poliglicerol poliricinoleata (PGPR) i poliglicerol estra jestivih masnih kiselina i njihovih sme&scaron;a, za dobijanje 20% V/U emulzija. Ispitivanjem uticaja sastava sme&scaron;e emulgatora i njegove koncentracije na formiranje adsorpcionog sloja na graničnoj povr&scaron;ini ulje/voda i osobine formiranih V/U emulzija odabran je najpogodniji sistem za stabilizaciju primarnih emulzija.<br />Nakon formulisanja stabilnih duplih V/U/V emulzija sa inkorporiranim vitaminima C i E, optimizovani su uslovi za dobijanje mikrokapsula umrežavanjem kompleksa proteina na kapima ulja pomoću genipina, a njihovo izdvajanje iz rastvora ostvareno je primenom Spray drying postupka. Karakterizacijom dobijenih mikrokapsula (ispitivanjem morfologije povr&scaron;ine, efikasnosti inkapsulacije vitamina C i E, kinetike otpu&scaron;tanja vitamina C u in vitro uslovima) zaključeno je da na osobine mikrokapsula utiče koncentracija umreživača, kao i interakcija između želatina i NaKN u kontinualnoj fazi emulzija V/U/V.</p> / <p>Microcapsules, as active substance carriers, have increasing application in different industries, especially in food and pharmaceutical industry. Incorporation of the biologically active substances inside the microcapsules allows masking of unpleasant taste and smell, protection od sensitive and volatile components.<br />The aim of this thesis is preparation of microcapsules for parallel incorporation of water and oil soluble active substances for their protection and controlled release. Microcapsules were formed from double water-oil-water emulsions (W/O/W) by coacervation method, depositing the coacervate formed in the system of two oppositely charged proteins, gelatin and sodium caseinate (NaCN), at the water/oil interface. As a model for water and oil soluble biological active substances, vitamins C and E were used.<br />First of all, interactions in the gelatin/NaCN system were investigated in detail, by using different methods (measuring of zeta potential, tensiometry, vicometry, rheological investigations). Based on these results, changes at the interface and in the bulk of the system, as well as mechanisms of coacervate formation were defined. It has been determined that at gelatin:NaCN mass ratio of 2:1 non soluble coacervate were formed.<br />Influence of the interactions in this system on properties of the W/O/W double emulsions, made by emulsification of primary water/oil (W/O) emulsions in gelatin/NaCN mixtures, at desired mass ratios of proteins, was investigated. It was concluded that interactions between proteins in continuous phase of emulsions have influence on their properties.<br />As the first step in formation of stable W/O/W emulsions is<br />obtaining stable primary W/O emulsion, possibility of using lipophilic emulsifiers, polyglycerol polyricinoleate (PGPR) and polyglycerol esters of edible fatty acids and their mixtures, for 20% W/O emulsions formation were investigated. Results of these investigations showed that composition of emulsifiers mixtures and their concentrations have an influence on adsorption layer, at the water/oil interface, formation, as well as on stability of W/O emulsion, and based on these results the most suitable system of emulsifiers were chosen.<br />After formulation of stable double W/O/W emulsions with incorporated vitamins C and E, conditions for microcapsules formation, by crosslinking of proteins complex at oil droplets with genipin, were optimized, and for their separation from dispersion spray drying method was applied. Characterization of obtained microcapsules (investigation of the surface morphology, efficiency of the vitamins C and E encapsulation, release kinetics of vitamin C under in vitro conditions) showed that concentration of crosslinking agent, as well as interaction between gelatin and NaCN, have an influence on microcapsules properties.</p>
3

Physico-Chemical and Microfluidic Approaches Toward Engineering Oscillating and Communicating Chemical Droplets / Approches physicochimiques et microfluidiques vers l'ingénierie oscillante et les gouttelettes chimiques communicantes

Torbensen, Kristian 28 September 2016 (has links)
La génération, propagation et la réception d’informations (bio/chimiques) entre les organismes individuels sont la clé de voûte de nombreux systèmes communicants intelligents et sont omniprésents dans la nature. Les colonies de lucioles synchronisent leurs flashs, et la contraction et l’expansion des muscles cardiaques sont quelques exemples parmi d’autres, où les signaux bio / chimiques générés par des sources synchronisées produisent un comportement coopératif. L’objectif final de cette thèse est de développer une plateforme fiable pour générer des réseaux de communication de liposomes, en encapsulant la réaction de Belousov-Zhabotinsky (BZ) en tant que source d’information ou un signal transmis, et d’étudier la dynamique d’un tel système. Pour atteindre cet objectif, plusieurs questions ont été abordées par une approche “bottom-up” et multi-échelle. Tout d’abord, nous avons étudié l’interaction entre des liposomes de DMPC dopés et non-dopés avec le cholestérol, l’acide myristique, tétradécylsulfate, tétradécylamine, et les espèces impliquées dans la reaction BZ en utilisant la diffusion de rayons X aux petits angles et par spectrophotométrie UV-visible. Des rangées 1D de micro-gouttelettes ont été fabriquées en encapsulant la réaction BZ en microgouttelettes au moyen de la microfluidique et la communication entre les gouttelettes adjacentes a été étudiée. Plus tard, nous avons démontré un système microfluidique facile à monter / démonter avec une conception robuste et une géométrie modulable pour générer des emulsions doubles d’eau dans l’huile dans l’eau (E/ H / O). Enfin, le comportement de ces doubles emulsions générées dans système microfluidique en utilisant des phosphoplipides comme tensioactif et du chloroforme comme phase huileuse, est rapporté. Nous avons montré, avec cette composition de la phase d’huile, que le comportement dynamique des émulsions doubles sous écoulement donne lieu à des phénomènes riches incluant la déformation et du “tip-streaming”. / Generation, propagation and reception of (bio/chemical) information between individual organisms are the keystone of many intelligent communicating systems, and are ubiquitous in Nature. Colonies of fireflies synchronize their flashes, and contraction and expansion of heart muscles are few examples among others, where bio/chemical signals generated by synchronized sources produce a cooperative behaviour. The final objective of this thesis is to develop a reliable platform for generating communicative networks of liposomes, encapsulating the Belousov-Zhabotinsky (BZ) reaction as source of information or transmitted signals, and to study the dynamics of such a system. To reach this goal, several issues were addressed by following bottom-up and multi-scale approaches. First we investigated the interaction between both bulk DMPC liposomes, and liposomes doped with cholesterol, myristic acid, tetradecylsulfate, tetradecylamine, and the species involved in the BZ-reaction by using small angle X-ray scattering (SAXS) and UV-visible spectrophotometry. Than 1D arrays of micro-droplets were fabricated by encapsulating the BZ reaction into microdroplets by means of microfluidics, and the communication between adjacent droplets was studied. Later, we demonstrated an easy to assemble/disassemble and robust design for a microfluidic device with adjustable geometry, for generating monodisperse water-in-oil-in-water (w/o/w) double emulsions. Finally, the behavior of w/o/w double emulsions generated in a microfluidic device, using phospholipids as surfactant and chloroform as the oil phase, was reported. We showed, with this composition of the oil phase, that the dynamic behaviour of the double emulsions under flow gave rise to different phenomena, such as deformation and tip-streaming.
4

Quelques opérations élémentaires en microfluidique digitale : encapsulation, fragmentation et trafic de gouttes / Few elementary operations in digital microfluidics : encapsulation, fragmentation and traffic of droplets

Schmit, Alexandre 25 September 2015 (has links)
Les écoulements de trains périodiques de gouttes monodisperses confinées dans des microcanaux sont largement utilisés pour diverses applications haut-débits en microfluidique digitale. Pour cela, il est nécessaire de réaliser différentes opérations sur ces gouttes comme les fragmenter, les fusionner ou les trier. Dans ce manuscrit, nous discutons de trois de ces opérations expérimentalement et théoriquement. La première concerne l’encapsulation d’un train de gouttelettes dans des gouttes. Nous étudions la dynamique d’encapsulation et nous présentons une nouvelle méthode d’encapsulation. Par suite, nous investiguons deux modes de fragmentation de gouttes, tous deux influencés par des interactions hydrodynamiques entre gouttes consécutives dans un train. Enfin, nous cherchons à comprendre la sélection du chemin suivi par des gouttes à des bifurcations successives. / Flows of periodic trains of monodisperse drops confined in microchannels are widely used for numerous high-throughput applications in digital microfluidics. The development of such applications requires performing and combining various operations on these drops like breakup, fusion or sorting. In this manuscript, we study experimentally and theoretically three of these operations. We first discuss the encapsulation of a train of droplets inside drops, focusing on the encapsulation dynamics. Also, we present a new way to encapsulate drops to produce double emulsions. We then investigate two ways to break drops against micro-obstacles, both being influenced by hydrodynamics interactions between two consecutives drops in a train. Lastly, we report the investigation of the path selection of drops at successive bifurcations.
5

Desenvolvimento de emulsões múltiplas cosméticas contendo óleo de girassol e óleo de gergelim: estudos de estabilidade físico-química / Development of cosmetic multiple emulsions containing sunflower oil and sesame oil: studies of physicochemical stability

Maciel, Náira Rezende 03 October 2012 (has links)
Atualmente, tem se dado grande importância à criação de novos sistemas de liberação de princípios ativos. Na área cosmética, os sistemas em destaque são nanoemulsões, emulsões múltiplas e emulsões contendo cristais líquidos/fase gel lamelar. Nas emulsões múltiplas coexistem emulsões dos tipos O/A e A/O. Elas possuem inúmeras vantagens sobre outros sistemas de liberação, como por exemplo, a possibilidade de veicular dois ativos incompatíveis em compartimentos diferentes e controlar o perfil de liberação dos mesmos. Além disso, possuem biocompatibilidade, completa biodegradabilidade e podem ser usados diferentes óleos e tensoativos. Outra tendência recente em cosmetologia é o emprego de matérias-primas vegetais associadas a sistemas de liberação de princípios ativos, para formulação de novos produtos com apelo comercial e sustentável. O objetivo deste trabalho foi desenvolver um novo sistema de emulsão múltipla, por etapa única, que tivesse estabilidade características diferenciadas. Para tanto, elegeu-se dois óleos vegetais: girassol e gergelim, que foram usados separadamente no desenvolvimento dessas emulsões. O método de emulsificação utilizado foi o método de inversão de fases (EPI). Foi determinado o EHL crítico para cada um dos óleos, 6,5 para o óleo de girassol e 5,0 para o óleo de gergelim. Os pares de tensoativos escolhidos para o estudo foram Steareth 2 - Steareth 20 para óleo de girassol e Span® 60 - R400 para óleo de gergelim. Foram construídos dois diagramas pseudoternários, um para cada sistema, com o objetivo de definir variáveis relevantes à composição (fração aquosa, fração oleosa, porcentagem de tensoativo). Foram selecionadas as melhores emulsões para prosseguimento dos estudos de estabilidade, avaliada por meio dos seguintes testes físico-químicos: medições de pH, condutividade elétrica, granulometria e medidas reológicas. O método de emulsificação em etapa única por inversão de fases se mostrou eficiente na produção de emulsões múltiplas estáveis. Foi desenvolvida uma emulsão múltipla com características diferenciadas a partir do óleo de girassol: emulsão múltipla contendo fase gel-lamelar, um sistema ainda não descrito na literatura. As características das emulsões múltiplas descritas nesse trabalho, a saber: o uso de óleos vegetais como os óleos de girassol e gergelim; baixas concentrações de tensoativos; multiplicidade dos glóbulos e fase gel lamelar no mesmo sistema; são características desejáveis para a indústria cosmética, o que as tornam potenciais sistemas de liberação de ativos. / Currently, it has been given great importance to the creation of new delivery systems for active ingredients. In the cosmetic area, the highlighted systems are nanoemulsions, multiple emulsions and liquid crystal/lamellar gel phase emulsions. In multiple emulsions coexist O/W and W/O types of emulsions. They have several advantages over other delivery systems, such as the possibility of carry out two incompatible active ingredients in different compartments and the control of the release of the same. Moreover, they have biocompatibility, biodegradability and different oils and surfactants can be used. Another recent trend in cosmetology is the use of vegetable raw materials associated with the delivery systems for active ingredients, to formulate new products with commercial and sustainable appeal. The objective of this study was to develop a new system of multiple emulsion, in one step emulsification, which have stability and distinctive features. It was selected two vegetable oils: sunflower and sesame, which were used separately in the development of the multiple emulsions. The method of emulsification used was emulsion phase inversion (EPI). The critical HLB of oils was, 6.5 for sunflower oil and 5.0 for sesame oil, respectively. The pairs of surfactants chosen for the study were Steareth 2 - Steareth 20 for sunflower oil and Span® 60 - R400 for sesame oil. We constructed two pseudo-ternary diagrams, one for each system, in order to define variables relevant to the composition (water and oil fraction, percentage of surfactant). We selected the best emulsions for further investigation. Stability of the emulsions was evaluated by the following physico-chemical tests: measurements of pH, electrical conductivity, particle size and rheological measurements. The method of one-step emulsification was efficient in producing stable multiple emulsions. A multiple emulsion from sunflower oil was developed with distinctive features: gel-lamellar phase multiple emulsion, a system not described yet. The characteristics of multiple emulsions described in this work, to know: use of vegetable oils, as sunflower and sesame oils; low concentrations of surfactants; multiplicity of droplets and lamellar gel phase at same system; they are desirable characteristics for the cosmetic industry, and they make these multiple emulsion potential delivery systems.
6

PROBIÓTICOS ENCAPSULADOS APLICADOS EM PRODUTO CÁRNEO / Encapsulated probiotics applied in meat product

Cavalheiro, Carlos Pasqualin 20 May 2016 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to encapsulate probiotic microorganisms, evaluating their resistance against harsh environments and the use in dry fermented sausages. L. plantarum ATCC 8041 and E. faecium ATCC 700221 were encapsulate in alginate beads in association with inulin, milk powder and trehalose through extrusion technique and submitted to stressful environments such as high temperatures, high concentrations of sodium chloride and sodium nitrite and refrigerated storage period. Subsequently, L. plantarum was added to dry fermented sausages as free cells or encapsulated using extrusion, emulsion and double emulsion techniques. Encapsulation was effective to protect probiotics against stress treatments, mainly 70 ºC temperature and high concentrations of sodium chloride and sodium nitrite. Furthermore, encapsulated probiotics kept their viability throughout 70 days of refrigerated storage. In addition, the use of encapsulated L. plantarum did not change physico-chemical properties of dry fermented sausage during processing and storage. However, the extrusion technique seems to be more effective to keep higher counts of L. plantarum in dry fermented sausages during processing and storage. The addition of L. plantarum encapsulated in emulsion and double emulsion increased lipid oxidation in dry fermented sausages. Furtermore, in sensory analysis, dry fermented sausages containing L. plantarum encapsulated in emulsion had lower scores than control treatment in flavor, hardness, texture and overall acceptance attributes. / Este trabalho teve por objetivo encapsular microrganismos probióticos, avaliar sua resistência frente à condições adversas de processamento e estudar a aplicação em embutido cárneo fermentado. Para isso o L. plantarum ATCC 8041 e E. faecium ATCC 700221 foram encapsulados através da técnica de extrusão usando alginato de sódio juntamente com inulina, leite em pó e trealose como materiais de cápsula e submetidos à condições adversas de processamento como altas temperaturas, altas concentrações de cloreto de sódio e nitrito de sódio e armazenamento sob refrigeração. Posteriormente, o L. plantarum foi adicionado na forma livre e encapsulado através das técnicas de extrusão, emulsão simples e emulsão dupla em embutido fermentado e avaliado durante seu processamento e armazenamento. Observou-se que a encapsulação foi eficaz na proteção dos probióticos às condições adversas, especialmente quando submetidos à temperatura de 70 ºC e altas concentrações de cloreto e nitrito de sódio. Os probióticos encapsulados se mantiveram em níveis adequados durante os 70 dias de armazenamento sob refrigeração. Ainda, a adição de L. plantarum encapsulado por diferentes técnicas não alterou as características físico-químicas do embutido fermentado durante seu processamento e armazenamento. No entanto, a encapsulação através da técnica de extrusão se mostrou mais viável em manter as contagens de L. plantarum em níveis mais elevados no produto durante o processamento e armazenamento. A adição de L. plantarum encapsulado em emulsão simples e emulsão dupla aumentou a oxidação lipídica dos embutidos fermentados. Ainda, na análise sensorial, os produtos contendo L. plantarum encapsulado em emulsão simples apresentaram notas inferiores ao controle nos quesitos sabor, dureza, textura e aceitação geral.
7

Desenvolvimento de emulsões múltiplas cosméticas contendo óleo de girassol e óleo de gergelim: estudos de estabilidade físico-química / Development of cosmetic multiple emulsions containing sunflower oil and sesame oil: studies of physicochemical stability

Náira Rezende Maciel 03 October 2012 (has links)
Atualmente, tem se dado grande importância à criação de novos sistemas de liberação de princípios ativos. Na área cosmética, os sistemas em destaque são nanoemulsões, emulsões múltiplas e emulsões contendo cristais líquidos/fase gel lamelar. Nas emulsões múltiplas coexistem emulsões dos tipos O/A e A/O. Elas possuem inúmeras vantagens sobre outros sistemas de liberação, como por exemplo, a possibilidade de veicular dois ativos incompatíveis em compartimentos diferentes e controlar o perfil de liberação dos mesmos. Além disso, possuem biocompatibilidade, completa biodegradabilidade e podem ser usados diferentes óleos e tensoativos. Outra tendência recente em cosmetologia é o emprego de matérias-primas vegetais associadas a sistemas de liberação de princípios ativos, para formulação de novos produtos com apelo comercial e sustentável. O objetivo deste trabalho foi desenvolver um novo sistema de emulsão múltipla, por etapa única, que tivesse estabilidade características diferenciadas. Para tanto, elegeu-se dois óleos vegetais: girassol e gergelim, que foram usados separadamente no desenvolvimento dessas emulsões. O método de emulsificação utilizado foi o método de inversão de fases (EPI). Foi determinado o EHL crítico para cada um dos óleos, 6,5 para o óleo de girassol e 5,0 para o óleo de gergelim. Os pares de tensoativos escolhidos para o estudo foram Steareth 2 - Steareth 20 para óleo de girassol e Span® 60 - R400 para óleo de gergelim. Foram construídos dois diagramas pseudoternários, um para cada sistema, com o objetivo de definir variáveis relevantes à composição (fração aquosa, fração oleosa, porcentagem de tensoativo). Foram selecionadas as melhores emulsões para prosseguimento dos estudos de estabilidade, avaliada por meio dos seguintes testes físico-químicos: medições de pH, condutividade elétrica, granulometria e medidas reológicas. O método de emulsificação em etapa única por inversão de fases se mostrou eficiente na produção de emulsões múltiplas estáveis. Foi desenvolvida uma emulsão múltipla com características diferenciadas a partir do óleo de girassol: emulsão múltipla contendo fase gel-lamelar, um sistema ainda não descrito na literatura. As características das emulsões múltiplas descritas nesse trabalho, a saber: o uso de óleos vegetais como os óleos de girassol e gergelim; baixas concentrações de tensoativos; multiplicidade dos glóbulos e fase gel lamelar no mesmo sistema; são características desejáveis para a indústria cosmética, o que as tornam potenciais sistemas de liberação de ativos. / Currently, it has been given great importance to the creation of new delivery systems for active ingredients. In the cosmetic area, the highlighted systems are nanoemulsions, multiple emulsions and liquid crystal/lamellar gel phase emulsions. In multiple emulsions coexist O/W and W/O types of emulsions. They have several advantages over other delivery systems, such as the possibility of carry out two incompatible active ingredients in different compartments and the control of the release of the same. Moreover, they have biocompatibility, biodegradability and different oils and surfactants can be used. Another recent trend in cosmetology is the use of vegetable raw materials associated with the delivery systems for active ingredients, to formulate new products with commercial and sustainable appeal. The objective of this study was to develop a new system of multiple emulsion, in one step emulsification, which have stability and distinctive features. It was selected two vegetable oils: sunflower and sesame, which were used separately in the development of the multiple emulsions. The method of emulsification used was emulsion phase inversion (EPI). The critical HLB of oils was, 6.5 for sunflower oil and 5.0 for sesame oil, respectively. The pairs of surfactants chosen for the study were Steareth 2 - Steareth 20 for sunflower oil and Span® 60 - R400 for sesame oil. We constructed two pseudo-ternary diagrams, one for each system, in order to define variables relevant to the composition (water and oil fraction, percentage of surfactant). We selected the best emulsions for further investigation. Stability of the emulsions was evaluated by the following physico-chemical tests: measurements of pH, electrical conductivity, particle size and rheological measurements. The method of one-step emulsification was efficient in producing stable multiple emulsions. A multiple emulsion from sunflower oil was developed with distinctive features: gel-lamellar phase multiple emulsion, a system not described yet. The characteristics of multiple emulsions described in this work, to know: use of vegetable oils, as sunflower and sesame oils; low concentrations of surfactants; multiplicity of droplets and lamellar gel phase at same system; they are desirable characteristics for the cosmetic industry, and they make these multiple emulsion potential delivery systems.
8

Development of microfluidic and low-energy emulsification methods for the production of monodisperse morphologically-complex nanocarriers : application to drug and contrast agent encapsulation / Développement de méthodes d’émulsification microfluidique et basse énergie pour la production de nanovecteurs monodisperses de morphologies complexes : application à l’encapsulation d’un principe actif ou d’un agent de contraste

Ding, Shukai 30 November 2016 (has links)
L’objectif de ce travail fut de développer et d’appliquer des technologies avancées de mélange et d’émulsification pour la préparation de nanovecteurs de morphologies complexes potentiellement utilisables en tant que produits pharmaceutiques. Premièrement, un procédé de nanoprécipitation assisté par micromélangeur fut utilisé pour obtenir et contrôler la taille de nanoparticules de PMMA chargées en Kétoprofène (100-200 nm). Combiné avec un appareil de séchage par pulvérisation, des nanoparticules sèches purent être obtenues dont les propriétés physico-chimiques furent proches de celles des particules non séchées. Ce microprocédé de nanoprécipitation permit également d’encapsuler des nanoparticules d’oxyde de fer (6 nm) dans des nanoparticules de PMMA de 200 nm avec une fraction massique de 60%. Pour augmenter la fraction solide de ces nanosuspensions et obtenir des particules sphériques de tailles plus petites (100 nm), une méthode de nanoémulsification basée sur un fort écoulement élongationnel fut employée. Deuxièmement, des émulsions et nanohydrogels doubles encapsulant un médicament hydrophile modèle dans leur cœur aqueux furent obtenus par couplage d’un microfluidiseur commercial pour l’obtention de l’émulsion primaire et d’une méthode d’émulsification basse énergie (émulsification spontanée) pour la double émulsification. La taille des nanovecteurs doubles a pu être variée grâce au rapport massique surfactant/huile (SOR) dans la gamme 80-80 nm. La colocation de deux sondes fluorescentes, placées dans le cœur et dans l’écorce, a pu être confirmée par microscopie confocale en fluorescence. La méthode d’émulsification spontanée fut également employée pour produire des nanolipogels (60 nm) chargées ou non de nanoparticules d’oxyde de fer et d’or (6 nm). / The aim of this work was to develop and apply advanced technologies in mixing and emulsification for the preparation of morphologically-complex nanocarriers for potential uses in pharmaceutics. Firstly, a micromixer- assisted nanoprecipitation process was used to get and to easily tune the size of Ketoprofen-loaded PMMA nanoparticles (100-200 nm). Combined with a commercial spray dryer, dry-state drug-loaded polymeric nanoparticles (NPs), which main physicochemical properties were close to those of non spray-dried NPs, were successfully produced. This nanoprecipitation microprocess also allowed encapsulating 6 nm iron oxide NPs into 200 nm PMMA nanoparticles with a weight ratio of 60%. To increase the solid content of the above nanosuspension and get spherical polymeric NPs of smaller sizes (100 nm), an elongational-flow nanoemulsification method was used. Secondly, double nanoemulsions/nanohydrogels encapsulating a hydrophilic model drug in the aqueous core droplets/hydrogel were obtained by the combination of a commercial microfluidizer for the primary emulsion and a low energy emulsification method (spontaneous emulsification) for the double emulsification. The size of the double nanocarriers was varied by means of the surfactant to oil ratio (SOR) in the range 80 to 180 nm. Colocation of two fluorescent probes located in the core and in the shell was confirmed by fluorescence confocal microscopy. The spontaneous emulsification method was also employed to produce nanolipogels whose size could be tuned down to 60 nm. These nanolipogels were also loaded with iron oxide nanoparticles (6 nm) or gold nanoparticles (6 nm).

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