Дисертації з теми "Encapsulation de cellules"
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Geisler, Hubert. "Structuration d'hydrogels thermoactivables pour l'analyse de cellules uniques." Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS001.
We present in this work a new microfluidic technology aiming at isolating single cells by the use of thermoactuable polymers. One of the polymers we use is polyNIPAM, a polymer that can expand its volume by 400% in water when the temperature is set under 32°C and can shrink down when it is set over 34°C. We use this reversible swelling capability to open and close compartments embedded in a microfluidic chip.Grafting and structuring these hydrogel features relies on thiol-en click chemistry, initiated thermally or by UV irradiation. We have developed methods and microfabrication protocols in order to diversify the substrate materials (from glass to PDMS, COC, PMMA, etc), to expand the structures thickness range (from few microns to a tenth of microns) and to strengthen our knowledge regarding the fabrication impact on the hydrogel’s behavior. A robust protocol of photolithography has finally been worked on allowing the design of any type of 2D features on a large choice of substrates.One of the realistic applications detailed here is the development of microfluidic chips aiming at isolating single cells in hydrogel compartments. (confidential)
Le, Vot-Morales Sophie. "Microsystème pour l’encapsulation de cellules pancréatiques." Université Joseph Fourier (Grenoble ; 1971-2015), 2009. http://www.theses.fr/2009GRE10191.
This study is devoted to the development of a microfluidic system for the encapsulation of islets of Langerhans. These clusters of cells secrete a pancreatic hormone (insulin) in order to regulate the blood glucose level. Encapsulation allows a considerable reduction in the amount of immunosuppressive therapy since the polymer capsule isolates the transplanted cells from the immune system. Major challenge for cell encapsulation are now to automate the encapsulation process and to control accurately the size, the polydispersity, and the shape of the capsules. The main purpose of this study was to evaluate the potential of microfluidics as a new technology for cell encapsulation. The immobilization material selected in this study is the alginate since it is the most commonly used polymer for cell encapsulation. Using a flow focusing geometry (MFFD), alginate droplet formation in an oil flow is characterized. Influence of viscosity and viscoelasticity of alginate solutions on droplet pinch-off is scrutinized. The gelling of alginate droplet has been investigated. A new gelling process has been developed, and its advantages on the classical gelation methods are discussed. It is recalled that the main challenges of the gelation on chip are to maintain the spherical shape of the capsules, and to respect the cell viability (pH7,4). Using the microfluidic devices that have been produced. Encapsulations of islets of Langerhans have been performed
Morlier, Arnaud. "Propriétés barrières de structures hybrides. Application à l'encapsulation des cellules solaires." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENI056.
Materials used in organic electronic devices or new generation photovoltaics undergo degradation byoxygen and water. In order to prevent their degradation, the devices should be encapsulated withmaterials showing a low permeability to oxygen and water vapor. For organic solar cellsencapsulation, material permeability to water (WVTR) and oxygen (OTR) should not exceed 10-3 g.m-2.d-1 and 10-3 cm3.m-2.d-1 respectively. The aim of this work is to study and develop a solutionprocessed,flexible, transparent and gas-barrier multilayer inorganic/organic hybrid structure, and tounderstand the mechanisms involved in diffusion limitation through these barriers.Firstly, this work has been dedicated to the realization on a polymer substrate of a thin silicon oxidelayer from an inorganic precursor: the perhydropolysilazane (PHPS). Different precursor conversionpaths have been studied and compared. The best barrier layers on polymer substrate have shownoxygen and water permeabilities of about 0,1 g.m-2.d-1 and 0,1 cm3.m-2.d-1 respectively. This result iscomparable to the permeability of plasma deposited layers.Multilayer hybrid structures have been realized by introducing a polymer layer between inorganiclayers in order to decorrelate the thin layer defects. This achieved permeabilities below 10-2 g.m-2.d-1for water and 10-3 cm3.m-2.d-1 for oxygen.The photovoltaic performances of encapsulated organic solar cells under illumination have beencompared over time. Encapsulation with the best barrier material developed during this work resultedin good device stability.This study has shown that entirely solution-processed barrier materials are a promising option for largescale organic solar cells encapsulation
Berthuy, Ophélie. "Puce à cellules multiplexée pour l'étude de réponses cellulaires parallélisées." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10133/document.
The work reported in this thesis focuses on the development of a multiplexed cell chip for the study of parallelized cellular responses. The lineage of cells from Prostate cancer LNCaP cells, were used as a study model thanks to their ability to secrete prostate-specific antigen (PSA) and β-2-microglobulin (B2M) in response to induction by hormones such as dihydrotestosterone (DHT). We were able to detect in real time these label-free molecules and their secretion by small populations of adherent LNCaP cells (from 1 to 100 cells) at specified positions on a SPRi biochip. Three different approaches were considered for this biochip. The first was to pattern the gold surface of a SPRi slide to obtain microwells whose bottom reveals the gold surface (cytophilic area) and an outer shell composed of polystyrene (cytophobe) to create an adhesive/non-adhesive surface for cell culture. Antibodies were immobilized in a controlled manner in the microwells using a piezo electric spotter. In this miniaturized system, different cell lines were co-cultured on a surface of 1 cm², paving the way for multiplexing. A small population of cells (1 to 100) was deposited in an automated manner into each microwell. In order to maintain the cells in a hydrated environment during deposition, a biocompatible alginate polymer was used. This method allows the encapsulation of cells in a very small volume (<50 nL). The ability of the hydrogel to maintain the encapsulated cells in a given position on the support led to the design of a second approach for the production of the biochip. In this second approach the surface is not altered and biological compounds (antibodies and cells) are directly deposited in an automated manner on the gold layer. Finally, a last approach was developed by immobilizing the cells on a patterned substrate placed in front of the sensitive layer SPRi. In all three approaches, the kinetics of PSA secretion and secreted B2M could be followed by SPRi
Gaume, Julien. "Etude du photovieillissement de matériaux nanocomposites pour l'encapsulation de cellules solaires organiques." Thesis, Clermont-Ferrand 2, 2011. http://www.theses.fr/2011CLF22173.
This work was devoted to the study of the photochemical behavior of polymer / clay nanocomposites with the aim to use these nanocomposites in a multilayer organic / inorganic coating for organic solar cells encapsulation. The goal of this work was to obtain polymer / clay nanocomposite films that are flexible, transparent, which can be processed by solution, and that are photochemically stable. In the first part, the characterization of nanocomposites based on polyvinyl alcohol (PVA) has shown their ability to be inserted into a multilayer system, particularly for gas barrier properties. The study of the photochemical behavior of PVA with the identification of photodegradation products allows us to propose a photooxidation mechanism of PVA and to determine the effects of photoageing on the film properties (roughness, permeability, transparency). The insertion of lamellar nanofillers (Montmorillonite, Laponite or Layered Double Hydroxide) in PVA induces different effects (prodegradant or stabilising) depending on the nature of the clay (natural or synthetic). However, in absence of oxygen, the PVA and PVA / clay nanocomposites are very photostable. Finally, encapsulation alternating inorganic SiOx layer and PVA or PVA / clay nanocomposite layer permits to obtain the permeability levels required for organic solar cells in niche markets (consumer electronics)
Dalle, Prisca. "Système intégré pour l'encapsulation monocouche de cellules." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENS036/document.
Epileptic seizures arise from pathological synchronization of neuronal ensemble.Seizures originating from primary motor cortex are often pharmacoresistant, and many times unsuitable for respective surgery because of location of epileptic focus in eloquent area. Basal ganglia play important role in seizure propagation. Micro electrode recordings performed during previous studies indicated that input structures of basal ganglia such as GPe, Putamen and Subthalamic nucleus (STN) are strongly modified during seizures. For example the mean firing rate of neurons of the STN and Putamen increased and the percentage of oscillatory neurons synchronized with the ictal EEG was higher during seizures as compared to interictal periods. Pilot studies in humans have shown the possible beneficial effect of chronic DBS applied to STN in treatment of pharmacoresistant motor seizures. Our study was aimed at studying the therapeutic effect of electrical stimulation of input structures of basal ganglia . We first developed a stable, predictable primate model of focal motor epilepsy by intracortical injection of penicillin and we documented it's pharmacoresistence. We then stereotactically implanted DBS electrodes in the STN and Putamen. The stimulator was embedded at the back of the animals. Subthreshold electrical stimulations at 130 Hz were applied to STN. Stimulator was turned ON when penicillin was injected. Sham stimulation at 0 volt was used as a control situation, each monkey being its own control. The time course, number and duration of seizures occurring in each epochs of 1 h were compared during ON and sham stimulation periods. Each experimental session lasted uptoo 6 hours,We also studied preventive high frequency stimulation of STN and subthershold low frequency stimulation of Putamen with 5 Hz and 20 Hz in the same model .Finally we studied combined effects of high frequency STN and low frequency Putamen stimulation in one monkey Results: Data was analysed from 1572 seizures in 30 experiments in three monkeys for chronic STN stimulation , 454 seizures in 10 experiments in one moneky during preventive STN stimulation ,289 seizures from 14 experiments in two monkeys during LFS putamen stimulation and 477 seizures from 10 sessions during combined STN and Putamen stimulation in one monkey The best results were observed during chronic STN stimulation The occurrence of first seizure was significantly delayed as compared to sham situation. Total time spent in focal seizures was significantly reduced by ≥69% on an average (p ≤0.05) after STN stimulation, due to a significant decrease in the number of seizures especially so during the first 3 hours after stimulation. The duration of individual seizures reduced moderately. Bipolar and monopolar stimulation modes were equally effective Preventive HFS STN (in one specimen) was not found to be superior to acute stimulation. LFS Putamen alone was effective but mainly in first two hours of stimulation .In a combined HFS STN and LFS Putamen stimulation the effect of stimulation in terms of seizure control was modest and poor compared to HFS STN alone or LFS Putamen alone. This study provides original data in primates showing the potential therapeutic effect of chronic HFS-STN DBS to treat focal motor seizures . A discussion explaining these
Authesserre, Claire. "Système microfluidique pour le contrôle et l'optimisation de l'encapsulation de cellules pour la thérapie du diabète." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS017.
Transplantation of microcapsules containing pancreatic islets, cell clusters regulating blood sugar, show promising results for type 1 diabetes therapy. However, many challenges remain to improve long-term graft functionality. The lack of standardization of current encapsulation technologies has aroused interest in microfluidic systems that enable more precision and automation.This thesis focuses on two of the current encapsulation technologies stakes: improving system productivity and microcapsules surface.In the first part of this thesis, we characterized a pressure-driven microfluidic flow focusing device (MFFD) droplet generation system. Analytical and numerical models were developed in order to determine and predict flow rates. Droplet formation was characterized as a function of the system input parameters. This study led to scaling laws enabling to predict these system input parameters in order to optimize alginate microcapsules production frequency.In the second part of this thesis, a microfluidic system enabling the production of core-shell microcapsules was developed. First experiments of pancreatic islets encapsulation have shown the ability of this system to minimize the immune reaction towards these capsules.This work is a first step towards encapsulation system optimization, which eventually, may provide capsules that meet all the capsule requirements for transplantation
Brousse, Benoit. "Réalisation et caractérisation de cellules photovoltaïques organiques obtenues par dépôt physique." Limoges, 2004. http://aurore.unilim.fr/theses/nxfile/default/18ec08d7-8895-42e8-841f-8700f4977e59/blobholder:0/2004LIMO0042.pdf.
Capone, Stéphanie. "Encapsulation d'hépatocytes dans un biomatériau poreux en vue d'une implantation dans un modèle animal." Compiègne, 2012. http://www.theses.fr/2012COMP2033.
Further to the lack of therapeutic solutions and the low number of hepatic transplants available to treat some hepatic diseases, tissue engineering and implantation of reconstructed tissue are possible alternatives to explore. Our approach is based on microencapsulation of hepatic cells in porous alginate beads. In a first time, this thesis work allowed to set up new combinations of materials based on alginate and to analyze their influence on bead mechanical behavior and on HepG2 C3A behavior. The results of this study shown that the adding of collagen and/or of poly-L-lysine coating increased the rigidity of the beads and decreased the mass transfer coefficients inside the bead while allowing a proliferation and a preservation of the functionality of HepG2 C3A. Then, the beads were implanted in small animal model of immunocompetent mice to estimate the biocompatibility of the different materials. In a second time, the primary human hepatocytes were encapsulated in beads of alginate mixed or not with type I collagen and cultivated during 7 to 14 days. The results have shown a basal loss of the level of the expressions and the activities of cytochromes P450 3A4 and 1A1, the functionality and the differentiation of encapsulated primary human hepatocytes. In a last time, encapsulated primary human hepatocytes were cultivated in two types of bioreactors in order to analyze the effect of dynamic culture conditions. The datas shown that the dynamic culture in fluidized bed bioreactor enhanced the functionality and the differentiation of encapsulated hepatocytes. This culture condition could be used before implantation of encapsulated hepatocytes in order to assure an optimal viability and a good maintenance of metabolic functions essential in a context of hepatic suppliance
Hached, Fahd. "Encapsulation de cellules stromales mésenchymateuses humaines dans les hydrogels polysaccharidiques : potentielle application dans le traitement de l'arthrose." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT1038/document.
Existing drug therapies for osteoarthritis (OA) provide, at best, symptomatic relief from pain and fail to prevent cartilage damage. Mesenchymal Stromal Cells (MSC) have generated interest since they secrete immunomodulatory factors. Direct injection of MSCs in OA suffers major limitations. To overcome these limitations, several studies have proposed to entrap MSC within biomaterials. However, their immunomodulatory properties after encapsulation have not been investigated. In this context, this work aimed to entrap MSC within spherical particles derived from alginate or from silanized hydroxypropyl methylcellulose (Si-HPMC) and to investigate their biofunctionality. First, a protocol of Si-HPMC particles generation was assessed. Alginate and Si-HPMC particles were characterized. Size, diffusion and mechanical properties of generated particles were studied and compared. Secondly, MSC were entrapped within alginate or Si- HPMC. Their viability and their ability to proliferate were evaluated for up to one month after encapsulation. Lastly, the biofunctionality of encapsulated MSC was investigated in order to harness their therapeutic properties for the treatment of OA. In summary, we have shown that: (i) alginate and Si-HPMC particles exhibit different properties; (ii) both alginate and Si-HPMC particles support MSC survival and (iii) MSC encapsulated in alginate or Si-HPMC are sensitive to pro-inflammatory cytokines and respond to this stimulation by increasing their secretion of bioactive factors. These findings are promising for a potential application of encapsulated MSC to OA treatment
Magisson, Jordan. "Validation préclinique de dispositifs implantables de délivrance d’insuline et d’encapsulation de cellules pour le traitement du diabète de type 1." Electronic Thesis or Diss., Strasbourg, 2022. http://www.theses.fr/2022STRAJ097.
Current treatments for type 1 diabetes aims to normalize glycemia via insulin therapy or pancreas and islet grafts. However, these approaches are limited by non-physiological administration route for insulin therapy and use of immune-suppresive drugs for grafts.To overpass these limitations, our work focused on validation of a physiological insulin delivery device and a cell encapsulation device which is immune protective.We demonstrated efficacy of our insulin delivery device, which was well tolerated in both small and large animal models, allowing efficient correction of glycemia via an hepatic first pass. Our cell encapsulation device, thanks to its pre-vascularization period, ensured survival and sustained function of insulin secreting cells on diabetic rats. In parallel, the device prevented formation by the recepient, of antibodies against encapsulated cells.Taken together, these data allow to consider these two approach as potential new treatments for type one diabetes
Grogg, Julien. "A novel Encapsulated-Cell technology for the delivery of therapeutic proteins : from bench to bedside." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASQ013.
Encapsulated cell therapy (ECT) holds a great potential to deliver sustained levels of highly potent therapeutic proteins to patients and improve chronic disease management. Yet the translational leap to clinical success has been hindered by the scarcity of an allogeneic cell line suitable for human therapeutic applications along with an adapted versatile and biocompatible encapsulation device that is scalable, and easy to administer, retrieve, or replace. Here, we report on the development of a biocompatible, cargo-agnostic, macroencapsulation device with optimized features for protein delivery. Such device is compatible with adherent and suspension cells, and can be administered and retrieved without burdensome surgical procedures. We showed that different cell lines producing different therapeutic proteins can be combined in the device. In parallel, we have generated a stable, immortalized human myoblast (IHM) cell line that can be genetically engineered to secrete diverse functional proteins. We performed ECT using these two components and assessed their combination both in vitro and in vivo for long term, sustained protein delivery. We demonstrated the ability of cytokine-secreting IHM cells encapsulated in our device and implanted in human skin to mobilize and activate antigen-presenting cells, which could potentially serve as an effective adjuvant strategy in cancer immunization therapies. Finally we investigated the efficacy of sustained, low-dose human anti-CTLA-4 delivered by genetically engineered IHM encapsulated in our device in the peritumoral region of human CTLA4 knock-in mice subcutaneously engrafted with MC38 colon adenocarcinoma cells. Overall, our results support that our technology may contribute to cell therapies for cancer, and potentially metabolic disorders, and protein-deficient diseases
Bobbara, Sanyasi. "Effect of Encapsulation and Light-soak on Charge Transport Properties in Organic Semiconductor –based Diodes." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0022/document.
Organic semiconductors (OSs) have garnered a great attention in the recent years due to their ease of processibility, optical and electrical property-tunability, and to their cost-effectiveness. They form the class of materials most suitable for flexible electronics and bioelectronics, especially in association with solutionprocessable inorganic/hybrid materials. However, the charge mobility in these materials is strongly affected by their structural and energetic disorder introduced by the defects that ‘trap’ the charge carriers. Depending upon the physical location of the traps and their distribution in energy, they could significantly affect the charge transport in a device. The present work strives to probe the interface and bulk defect states in polymer-based diodes. In lieu of that, a part of the study involved characterizing the device with and without encapsulation, using techniques to record steady-state current-voltage (IV)behaviour, transients of charge extraction by linearly increasing voltage (CELIV) and dark-injection transient currents (DiTC), as well as photoluminescence (PL) and electroluminescence (EL) off the devices. The same characteristics have been carried out to observe the effect of ultra-violet (UV) lightsoak on the devices. All the tests were performed on three different polymers, namely P3HT, MDMO:PPV and PCDTBT. The comparison of the encapsulated versus unencapsulated devices gives an insight into characteristic differences in the measurables upon exposure to air and moisture. The light-soak tests indicate the modification of the cathode work function after a UV-assisted oxygen desorption off the polymer/cathode interface. A simultaneous effort went into an in-situ investigation of charge transport dynamics in organic semiconductors over wide time range at a microscopic scale
Tran, Nhu Mai. "Microencapsulation de cellules hépatiques pour des études de virologie." Compiègne, 2012. http://www.theses.fr/2012COMP2023.
Three dimensional (3D) hepatocyte cell culture and tissue engineering nowadays finds new applications in bioengineering, and more specifically in virologyand for hepatitis C studies. Indeed, the establishment of new antiviral strategies requires culture model for hepatitis C virus (HCV) that mimics the physiology of natural infection. New culture models permissive to HCV would thus appear as a promising innovation for HCV studies and mass production of virus. This PhD thesis is part of this perspective and focuses on the development of a 3D culture model of human hepatic cells. It is based on the microencapsulation of a hepatic cell line (Huh-7), permissive to HCV in calcium alginate porous beads. Our experimental approach is based on the physical and biological characterization of this model, after changes in the composition of the material (viscosity and concentration of sodium alginate, or polyethylene glycol (PEG) grafting). The results of these studies permitted to identify a condition for encapsulation which combines a matrix porosity compatible with viral infection with an adequate cell behavior due to a 3D cell organization and the expression of HCV membrane receptors. This culture model was submitted to various infection tests with HCV and others hepatotropic viruses. In contrast with the hypothesis leading to optimal encapsulation conditions, we showed that hepatic cells were not infected or did not produce viral particles, regardless of the virus and infection conditions used. These unexpected results open up innovative prospects in the context of cell transplantation
Obscur, Jean-Charles. "Amélioration des performances des cellules solaires organique par l'ingénierie de bandes aux interfaces électrodes semi - conducteurs." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0021/document.
The current context of strong growth in energy demands in the world requires diversification of its production, in particular towards renewable sources while limiting as far as possible the emission of greenhouse gases. Among the most promising and abundant renewable energies is solar energy and it is evident that solar, thermal or photovoltaic energy represents a crucial issue to reduce the consumption of fossil energy. Currently 90% of the solar generators are made of crystalline silicon, which poses a problem of supply of raw material, as silicon producers did not know how to anticipate the strong expansion of the solar sector. Innovative concepts present a high potential in terms of cost of production and application, in particular organic and hybrid (organic / metal oxide) dies. In Europe, France is very active in this area of research, particularly with regard to the use of new organic nanostructured materials or hybrid structures. This is why Disasolar, a French start-up specializing in flexible photovoltaics, wants to develop this activity by developing flexible solar modules by inkjet printing. The objectives of this thesis are to study new printable interface materials and to evaluate the effect of nanoparticle size on the topology and performance of devices. And secondly, the study will focus on the printing of interface materials and the stability of organic solar cells
Barulina, Elena. "Study of the photostability of organic solar cells : impact of materials and encapsulation processes." Electronic Thesis or Diss., Aix-Marseille, 2020. http://theses.univ-amu.fr.lama.univ-amu.fr/201209_BARULINA_247fcnnrd470uh345hs973z_TH%20(1).pdf.
Despite a strong increase in the electrical conversion efficiencies of organic solar cells, their long-term stability is a key factor for their commercial viability and therefore needs to be examined in detail. The objective here was to study the lifetime of organic solar cells by varying the active materials in the D:A mixture, the cell architecture, the interfacial layers, the treatments applied and the encapsulation process. Regardless of these parameters, a high stability could be obtained for PC71BM-based devices under LED. On the other hand, under AM1.5, a post-annealing process considerably improves the stability of the devices, but the choice of the cell structure remains the key parameter where only cells with normal structure showed a high stability over time. These layers were studied by absorption spectroscopy, AFM, XRD and analytical TEM. PC71BM-based devices can thus serve as a reference in the study of the stability of mixtures based on NFAs (PBDB-T:ITIC and PBDB-T-2F:ITIC-4F). Regardless of the illumination (LED or AM1.5) and the various parameters, NFA-based solar cells are unstable. Under LEDs, ITIC-4F-based solar cells have a better stability than ITIC-based solar cells, but this degradation also depends very strongly on the chemical nature of the electron extraction layer. Flexible encapsulation processes on ink-jet-printed modules from Dracula Technologies have been evaluated. These modules demonstrated relatively stable properties after 1000 hours of continuous illumination by a non-UV-filtered xenon lamp
Chabert, Max. "MICROFLUIDIQUE DE GOUTTES POUR LES ANALYSES BIOLOGIQUES." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00180994.
Dans une première partie, nous décrivons la conception d'un système permettant d'effectuer en flux et sans contamination la réaction de PCR dans des microgouttes transportées par une huile immiscible. Cette étude a débouché sur une plateforme automatisée au débit théorique de 3000 échantillons par jour, égalant les systèmes actuels avec une consommation 50 fois moindre en réactifs.
Dans les parties suivantes, nous présentons deux nouvelles idées pour la manipulation d'objets en microfluidique digitale : l'utilisation de phénomènes hydrodynamiques pour encapsuler des cellules uniques dans des microgouttes et les trier, et l'application de champs électriques pour induire mélange et coalescence de gouttes aqueuses. La combinaison de ces deux méthodes au sein d'une même puce est le premier pas vers un système intégré d'analyse de cellules uniques.
Kuehn, Carina Brigitte. "Développement et études comparatives de méthodes pour améliorer la survie et les fonctions de cellules productrices d'insuline et d'îlots pancréatiques endocriniens porcins en conditions de culture in vitro et de stress apoptotiques." Thèse, Université de Sherbrooke, 2014. http://hdl.handle.net/11143/5411.
Ogier, Stéphane. "Étude et optimisation de procédés d’encapsulation de cellules photovoltaïques." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0396/document.
Photovoltaic (PV) cells, for solar modules or panels, are protected from environmental stresses by polymeric encapsulants, which are mostly crosslinked elastomers. The optimization and the control of the encapsulation step have a twofold interest by increasing PV module lifetime and productivity, thus leading to a decrease of the cost of generated electricity. Two main directions have been investigated in this work: 1) The first one is related to the study of the crosslinking degree of the main industrial PV polyolefin encapsulant, EVA, which is a copolymer composed of ethylene and vinyl acetate, used currently in film form. Indeed, poor crosslinking level can lead to its creep, impacting directly the module lifetime. To overcome this problem, the quality control needs to be improved, by the evaluation of the crosslinking degree obtained while using the conventional encapsulation process (through lamination of encapsulant foils). Thus, the comparison of several methods to evaluate this degree are led ;2) The second direction concerns the study of a new encapsulation process. Indeed, the conventional lamination process potentially creates mechanical stresses in the PV cells, which as a consequence may limit the PV module lifetime. Moreover, lamination requires a relatively long processing time. To overcome this problem, the development of a new encapsulation process using a photopolymerizable encapsulant, initially liquid, decreases the production costs of PV modules and potentially increases their lifetime. The rheology properties and the polymerization kinetics of the new encapsulant are studied. At the end of the present work, both encapsulation processes are compared. Electrical performances of PV cells are measured before and after encapsulation as well as before and after ageing cycles. It has been revealed that the new encapsulation process presents at least as good, if not better performances than the standard process, thus highlighting its big potential for the manufacturing of PV modules
Bouhlel, Wafa. "Procédé d'encapsulation à base d'hydrogels pour le développement de micro-tissus cellulaires." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS414.
This thesis concerns the improvement of a hydrogel encapsulation process for three-dimensional cell culture. Submillimetric capsules are formed via high speed co-extrusion of macromolecules solutions, thereby forming a compound jet. The drops resulting from the fragmentation of the jet have a core/ shell type geometry where shell is composed of alginate. This layer is then solidified after immersion in a gelling bath. The use of biological materials required the implementation of a sequential injection system to manipulate small volumes, less than 1 mL. This approach is then accompanied by a longitudinal variation of the concentration of the suspended particles flowing in the injection tube. This dispersion can be inhibited by adding air bubbles at each end of the sample to segment it. A destabilization of the suspension initially homogeneous is observed when liquid inertia comes into play at the particle’s scale. These micrometric particles induce a flapping motion and jet speed fluctuations causing the coalescence of the drops and thus a size polydispersity. Finally, a collagen hydrogel, which mimics an extracellular matrix, has been implemented in the capsule’s core to promote adhesion of epithelial cells forming intestine and bile ducts. Within this matrix, the cells form a polarized and functional epithelium. The formation of these collagen capsules required the formulaiton of the collagen solution compatible with the process and the physiological conditions of the cells
Gautier, Aude. "Etude des écoulements et des transferts de masse dans différentes géométries de foie bioartificiel." Phd thesis, Université de Technologie de Compiègne, 2008. http://tel.archives-ouvertes.fr/tel-00360206.
Dans ce travail, l'objectif a été de caractériser différentes géométries de foie bioartificiel en comparant les fonctionnalités de mêmes cellules (C3A):
1) lit fluidisé classique (la référence) avec des billes d'alginate de 1000 µm de diamètre
2) nouveau type de fluidisation avec des billes de diamètre plus faible (600 µm)
3) dispositifs à fibres creuses utilisés classiquement par des équipes concurrentes
4) système Air Lift doté d'un apport d'air permettant la circulation du fluide
Dans chaque système, les écoulements et les transferts de matière des nutriments et des métabolites ont été caractérisés en absence et en présence de cellules de façon expérimentale et à l'aide de modèles mathématiques.
Dans les cas 1 et 2, il s'est avéré que les transferts de masse étaient quasiment identiques pour les diamètres de billes 600 et 1000 µm. La viabilité et les fonctionnalités des cellules ont été étudiées sur 48h de culture montrant des résultats très satisfaisants et prouvant ainsi l'innocuité du dispositif. Dans le cas 3, différents types de fibres creuses ont été caractérisées, permettant de déduire que la membrane de porosité intermédiaire est la plus prometteuse en vue de l'application clinique. Dans le cas 4, le système Air Lift a pour avantage d'avoir un coefficient de transfert de masse plus important que dans le cas du lit fluidisé, en absence de cellules
Pasqua, Mattia. "Preclinical studies on an extracorporeal bioartificial liver." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2557.
For all patients suffering of acute liver failure, there is an urgent need of alternatives to liver transplantation. Due to a variety of factors, those patients do not always have easy access to an available organ and die waiting for a transplant. Therefore, it is imperative to find viable alternatives to liver transplantation. Among the various alternatives that emerged in recent years, our group has mainly investigated the concept of bioartificial liver. It is an extracorporeal circulation device equipped with artificial elements (activated charcoal and ionic resin) and a biological element (hepatic biomass) capable of supporting the failing organ. This device has the role of providing hepatic functions, lost due to the disease, helping the patient to remain alive until an organ is available or, otherwise, capable of promoting natural liver regeneration. This thesis retraces the evolution of these devices over time, describing their principle of operation and the main results proposed by the literature. The focus is then moved on the development of our liver supply device and the scientific path that allowed optimizing the hepatic biomass at best. This thesis work led to the development of a ready-to-use BAL device on animal models of acute liver failure
Laporte, Camille. "Potentiel cytoprotecteur des cellules souches mésenchymateuses sur les îlots exposés à des cytokines pro-inflammatoires ou encapsulés : identification de facteurs pouvant améliorer leur statut oxydatif et inflammatoire." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAS015.
Although, the metabolic results of islets transplantation for patient with type 1 diabetes are now well documented, they are counteracted by the adverse effects of immunosuppressive therapies and the long-term loss in graft functionality.During this thesis, we worked on two complementary approaches offering the perspective of avoiding immunosuppressive treatment while protecting islets from apoptosis and loss of functionality induced by the mechanisms of isolation, culture and transplantation. These two tools are islet immunoisolation in capsules composed of specific biomaterials and islets co-transplantation with mesenchymal stem cells (MSCs) described for their immunomodulatory, proangiogenic and cytoprotective properties.In the european project of bioartificial pancreas BIOCAPAN, we have evaluated in vitro the biocompatibility of several biomaterials and we have highlight a combined effect of the presence of MSCs and tripeptides RGD on the viability and the functionality maintenance of the encapsulated islets. Subsequent in vivo validation of the biocompatibility and the added effect of the BIOCAPAN capsule on diabetic animals will allow the final validation of the capsule to be proposed for clinical trials.We also demonstrated, in an islet co-culture model with MSCs under conventional culture conditions and exposed to pro-inflammatory cytokines, that MSCs regulate the secretory capacity of islets probably via the regulation of heme oxygenase 1 (HO-1) described for its antioxidant and anti-inflammatory properties. The identification of transcription factors regulating HO-1 as well as mediators, allowing communication between the two cell types, are development perspectives.This work underlined the interest, within an immuno-isolation approach, of the reconstitution of a favorable environment within the capsule allowing the preservation of islet physiology thanks to the use of MSCs
Heitfeld, Kevin A. "Hydroxypropyl Cellulose for Flavor Encapsulation." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1163785195.
Moustafa, Tarek Mohamed Mohamed. "Microencapsulation de cellules chromaffines bovines dans le traitement des douleurs chroniques rebelles : étude de faisabilité in vitro et in vivo." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/45/.
Adrenal medullary chromaffin cells secrete a combination of pain reducing neuroactive substances including catecholamine and opioid peptides that alleviate both acute and chronic pain not only in several animal models but also in some clinical applications. But, the xenografts can not maintain their survival in central nervous system for a long period without the implication of immunosuppressive drug. In this context, the concept of immune-isolation by cell encapsulation seems to have a great interest in the field of cell therapy in order to protect the transplant from the host’s immune system. In the present study, we report the viability and functionality of bovine chromaffin cells (BCC) encapsulated in microcapsules of alginate/poly-L-lysine/alginate (APA) with a liquefied inner core both in vitro and in vivo in rats. The microencapsulation of BCC not only allows the cells to keep their viability and functionality but also to retain their pharmacological integrity as indicated by expression of tyrosine hydroxlase, met-enkephalin and secretion of catecholamine. The in vivo study concerning the implantation of both microencapsulated chromaffin cells and empty microcapsule in the central nervous system of rats aimed to evaluate the cellular viability and functionality of microencapsulated cells and to determine the host reaction against the implanted microcapsules. This study showed that the microencapsulated cells maintain their viability and their functionality three weeks after implantation in sub-arachnoid space of rats. In addition, this study gave us an account very interesting concerning the absence of immunological response against the implanted microcapsules. This approach may offer a useful potential for cell transplantation in the management of many clinical problems including intractable pain and degenerative diseases. However, other investigations are still necessary before application of this strategy in human clinics
Legrand, Alain. "Liposomes cibles et vecteurs retroviraux pour le transfert et l'expression du gene de la preproinsuline i de rat dans des cellules eucaryotes." Orléans, 1987. http://www.theses.fr/1987ORLE2011.
David, Bertrand. "Mise en place et validation d'un modèle in vitro pour l'étude des propriétés mécaniques, diffusives et métaboliques d'un Foie bioartificiel à lit fluidisé." Phd thesis, Université de Technologie de Compiègne, 2002. http://tel.archives-ouvertes.fr/tel-00003223.
Haji, mansor Muhammad. "Functionalized polymer implants for the trapping of glioblastoma cells Development of a non-toxic and non-denaturing formulation process for encapsulation of SDF-1α into PLGA/PEG-PLGA nanoparticles to achieve sustained release Reversing the Tumor Target: Establishment of a Tumor Trap". Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0015.
Glioblastoma (GBM) is the most common and lethal form of brain cancer. The diffusive nature of GBM means the neoplastic tissue can not be removed completely by surgery. Often, residual GBM cells can be found close to the border of the resection cavity and these cells can multiply to cause tumor recurrence in ≥90% of GBM patients. An implant that can sustainably release chemoattractant molecules called stromal cell-derived factor-1α (SDF-1α), which bind selectively to CXCR4 receptors on the surface of GBM cells, may be useful for inducing chemotaxis and recruitment of the residual GBM cells. This may then give access to selective killing of the cells and ultimately reduce tumor recurrence. In this work, SDF-1α was initially encapsulated into poly-lactic-coglycolicacid (PLGA)-based nanoparticles. A high encapsulation efficiency (76%) could be achieved using a simple phase separation process. The SDF-1α-loaded nanoparticles were then incorporated into a chitosan-based scaffold by electrospinning to obtain nanofibrous implants that mimic the brain extracellular matrix structure. In vitro release study revealed that the implant could provide sustainedSDF-1α release for 5 weeks. The gradual SDF-1αrelease will be useful for establishing SDF-1α concentration gradients in the brain, which is critical for the chemotaxis of GBM cells. A 7-day in vivo biocompatibility study revealed evidence of inflammation at the implantation site without any visible signs of clinical deterioration in the animal subjects. A long-term study (100 days) aiming to confirm the in vivo safety of the implants before proceeding to efficacy studies in a suitable GBM resection model is currently underway
Celebi, Duygu. "Oxidised cellulose gels and films for encapsulation and release." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675724.
Najberg, Mathie. "Development, physico-chemical characterization and biological evaluation of silk fibroin/hyaluronic acid freeze-dried sponges for the trapping of Glioblastoma cells Reversing the tumor target: Establishment of a tumor trap Development of a non-toxic and non-denaturing formulation process for encapsulation of SDF-1α into PLGA/PEG-PLGA nanoparticles to achieve sustained release". Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0040.
Glioblastoma (GBM) is a devastating tumour of the central nervous system. Despite an aggressive treatment, recurrence is inevitable, and the application of an effective therapeutic strategy remains a challenge. The breakthrough concept of cancer cell trap may offer new hopes and opportunities. The goal is to attract and confine the residual cancer cells surrounding the surgical cavity in a biomimetic polymeric scaffold delivering chemoattractive molecules. The stromal cell-derived factor-1α (SDF-1α), also called CXCL12, binds selectively to the CXCR4 receptor on the surface of infiltrative GBM cells and may be useful for inducing chemotaxis and the recruitment of residual GBM cells. In this work, series of freeze-dried sponges were prepared by combining silk fibroin (SF), hyaluronicacid (HA), poly-L-lysine (PLL) and heparin crosslinked with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimidehydrochloride (EDC) and N-hydroxysulfosuccinimidesodium salt (NHS). Sponges showed high porosity (near 90%) with mean pore diameters ca. 60 μm and contained up to 95% water once hydrated. They presented a soft texture close to the one of a brain with a Young’s Modulus down to 6 kPa. Moreover, addition of SF in the formulation yielded sponges with greater stability in PBS than the HA-PLL sponges. SF-HA and SF-HA-hep sponges were able to retain 75% and 93% of the SDF-1 protein respectively after 7 days in PBS supplemented with enzymes (hyaluronidase and heparinase). In vivo studies showed that the SF-HA and SF-HA-hep sponges were well tolerated in rats’ brain and that the SF-HA-hep sponge did not release SDF-1α after 7 days in the brain
Abdi, Sofia. "Preparation and process optimization of encapsulating cellulose microspheres." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174287.
Topolniak, Ievgeniia. "Photodegradation of polymer nanocomposites for encapsulation of organic solar cells." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22630.
The goal of this work was to develop EVOH/zeolite nanocomposites based on inorganic fillers such as zeolites for potential encapsulation of OSCs and to investigate their photochemical behaviour. The research was focused on the photooxidation mechanism of pristine EVOH copolymers and on the impact of the filler addition on this mechanism. EVOH/zeolite nanocomposites functional properties were characterised taking into account different particle sizes and filler contents. Properties of EVOH copolymers and EVOH/zeolites nanocomposites such as optical transparency, surface morphology, mechanical and thermal properties, and water uptake properties were investigated. On the basis of obtained results, the best candidate(s) for encapsulation of organic solar cells has been proposed. The chemical degradation mechanism of pristine polymers has been proposed, the materials photostability and the impact of the zeolite particles on the photochemical behaviour of the polymer have been studied. Electrical calcium test and performance of encapsulated OSCs were carried out in order to evaluate the ability of the studied materials to be used as potential candidates for efficient and stable encapsulation coatings for OSCs applications
Heitfeld, Kevin A. "Smart Membranes: Hydroxypropyl Cellulose for Flavor Delivery." Cincinnati, Ohio : University of Cincinnati, 2007. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1179357187.
Advisor: Dale Schaefer. Title from electronic thesis title page (viewed Apr. 2, 2009). Keywords: Flavor; Encapsulation; Smart Polymers; Responsive Polymers; Controlled Release; Spray Drying. Includes abstract. Includes bibliographical references.
Finn, Kristina Kateri. "Cellular Encapsulation Techniques: Camouflaging Islet Cells from the Immune and Inflammatory Responses Associated with Islet Transplantation." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_theses/231.
Garenne, David. "Etude d'un système de transition basé sur des acides gras dans les processus d’encapsulation de biomolécules : vers un nouveau modèle de cellule minimale." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0365/document.
Compartmentalization is of importance for our understanding of the emergence of life on earth but also for the development and design of minimal cells. Coacervation phenomenon allows spontaneous sequestration by molecular diffusion from aqueous medium but do not allow encapsulation of molecule inside. On the contrary, vesicular systems do not allow spontaneous encapsulation of molecules inside. Here we introduce a model built from saturated long chain fatty acids. This system can form both membranous vesicles and membrane free coacervated droplets that result from clouding by decreasing ph. We have shown that a large amount of proteins is encapsulated into vesicles after pre-crowding into coacervated. Encapsulation of enzyme in vesicles allow to increase the reaction rate compared to the reaction rate in diluted medium. Synthesis of proteins by cell-free system and metabolic reactions with proteins of mollicutes have not clearly been shown but they represent an essential element in the development of a minimal cell
Levin, David Michael. "An integrin required for the encapsulation immune response in the tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae)." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/412.
Leslie, Shirae. "The controlled release of rat adipose-derived stem cells from alginate microbeads for bone regeneration." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48946.
Cahall, Calvin Frank. "SURFACE FUNCTIONALIZATION VIA PHOTOINITIATED RADICAL POLYMERIZATION FOR RARE CELL ISOLATION AND MECHANICAL PROTECTION." UKnowledge, 2018. https://uknowledge.uky.edu/cme_etds/93.
Fors, Lisa. "Ecology and evolution in a host-parasitoid system : Host search, immune responses and parasitoid virulence." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-115243.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.
Harris, James Patrick. "The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439.
Nelson, Kimberly Lynn. "Enhanced performance and functionality of titanium dioxide papermaking pigments with controlled morphology and surface coating." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24645.
Committee Chair: Yulin Deng; Committee Member: Arthur Ragauskas; Committee Member: Jeff Empie; Committee Member: Jeffery Hsieh; Committee Member: Preet Singh
Lieber, Diana. "Functional assays for screening antibody activity in droplet-based microfluidics." Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/LIEBER_Diana_2010.pdf.
High-throughput, cell-based assays require small sample volumes to reduce assay costs and to allow for rapid sample manipulation. However, further miniaturisation of conventional microtiter plate technology is problematic due to evaporation and capillary action. To overcome these limitations, we developed droplet-based microfluidic platforms in which cells are grown in aqueous microcompartments separated by an inert perfluorocarbon carrier oil. Furthermore, this system allowed for an automated analysis of individual compartments subsequent to an incubation period as required for high-throughput, cell-based assays. In addition, we focused on the development of functional assays for screening antibody activity, e. G. Neutralisation of HIV or the inhibition of ACE-1. Common high throughput approaches for antibody screening use phage display or hybridoma cells. Phage display is powerful but based on binding properties rather than neutralising effects. Hybridoma cells allow for direct screening of neutralising activity, but are very restricted in the number of clones that can be screened due to their generation and proliferation as required for conventional screens. The aim of this study was the development of novel screening technology with the ultimate goal of screening single antibody-releasing cells (hybridoma cells). This system should also allow for direct B-cell screening. Once established, this technology could be used for the screening/ selection of many more therapeutic antibodies
Langlois, Geneviève. "Effets de la purification d’alginate et de la co-encapsulation avec des cellules canaliculaires sur la survie et fonction d’îlots de Langerhans microencapsulés." Thèse, 2010. http://hdl.handle.net/1866/3676.
Islets transplantation can normalize glycaemia in diabetic patients but only with the use of immunosuppressive drugs. The elaboration of an alginate microcapsule to immunoprotect the islets has been developed to overcome the use of those harmful drugs. However, one problem still subsists: the limited survival of the transplant. Two different aspects to overcome this problem will be discussed in this thesis: the use of purified alginate and the co-encapsulation of islets with pancreatic duct cells. The first study investigated a new proposition: the direct effects of non-purified alginate, compared to the purified one, on the survival of encapsulated islets. This was demonstrated by in vitro studies on the islets long-term viability, function and the incidence of their death by apoptosis and necrosis. These investigations helped us to conclude that purified alginate can maintain a better long-term survival and function of encapsulated islets. This investigation also demonstrated that alginate contaminants have a direct influence on encapsulated cells besides their role in immune cell activation; which have an indirect implication in the encapsulated islets death. The second study investigated the possible effects of pancreatic duct cells when co-encapsulated with islets of Langerhans. The results showed no significant effects on the viability of co-encapsulated islets, by viability and cellular death assays, and neither on their function in vivo tested with implantations in a mouse immmunodeficient model. To conclude, alginate purification appeared to improve the survival of encapsulated islets while pancreatic duct cells failed to do the same.
Chuang, Kai-En, та 莊鍇恩. "Encapsulation of β-Carotene by microfabrillated Cellulose". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/m3fsyk.
國立臺灣大學
食品科技研究所
105
Encapsulation is an expanding technique used in food industry. By coating sensitive target ingredient with wall material, many benefits will be provided. And one of the most important advantages is to improve the chemical stability. Light, heat and oxygen can be resisted by wall material, and extend shelf life of core. In this study, milled cellulose, a potential wall material, is used to encapsulate β-carotene by spray-drying. The influence of different homogenization methods of spray-dried infeed solution on encapsulation efficiency is investigated. And the effect of protection to β-carotene will be evaluated through storage stability analysis. 5.5 %(w/w) cellulose was media milled for 45 minutes, and then 3 % (cellulose base) β-carotene was added. The mixtures were processed by rotor-stator mixing (polytron) or 1-5 passes high pressure homogenization (HPH 1-5) to be infeed solution, and spray dried at 130 oC. It showed that the viscosity of infeed solution increased when HPH times increased, and particle size of cellulose became larger. HPH disperse β-carotene more evenly. HPH1 show highest effect of Encapsulation of β-carotene. During 28 days storage at dark conditions, β-carotene retention were increased after encapsulated. And half-life value was prolonged. It indicates that encapsulation can protect β-carotene from degradation when storage, and HPH1 is the best method to preparation the mixture.
Luo, Shao-Jyun, and 羅少君. "Morphology and encapsulation of media milled cellulose after spray drying." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/73977019802149917449.
國立臺灣大學
食品科技研究所
103
The change in particle morphology has resulted in variations of physicochemical properties and functions. Spray drying is a method to fabricate particles with a controllable size and morphology. During solvent evaporation, colloidal particles were self-assembled inside the droplet toward a close-packed array. With different particle sizes, which is one of the factors aggregating final particle morphology. In our laboratory, spherical cellulose particles have been prepared by utilizing media milling and spray drying. This study was to investigate the effect milling time on morphology and media-milled and spray dried cellulose, its encapsulation efficiency for b-carotene was also evaluated. 5% (w/w) microcrystalline cellulose was media milled for 15, 30, 45 and 90 minutes, and successively was spray dried at 130℃. The data showed that the particle size was decreased as the milling time increased. It appeared that, smaller particles particularly nano/submicron particle were prone to aggregate under the condition of nano/submicron scale particle size. Scanning electron micrograph, the spray dried cellulose powder from 15 min media-milled cellulose exhibited has highly rough surface. When the media milling time increased, the percentages of nano/submicron particles were increased. And the surface spray dried powder became smoother; with a decrease in apparent density and surface area. Data of porosity and density showed that the spray dried cellulose powders were dense particles. Obviously, raw cellulose would not the alike encapsulate b-carotene (encapsulation efficiency of 2.52%). The encapsulation efficiency of media-milled cellulose for 15, 30, 45 and 90 were 19.38, 23.57, 26.36 and 21.19%, respectively. It indicated that size reduction enhanced significantly the encapsulation behavior of cellulose. Among all the milling time tested, 45 min-milling was better choice for encapsulation.
WANG, YI-MIN, and 王逸民. "Micronization of Hydroxypropyl Cellulose and Drug Encapsulation Using Supercritical Assisted-atomization Process." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/77828959454855115628.
明志科技大學
化學工程系碩士班
104
The hydroxypropyl cellulose (HPC) and drug-carrier composite particles were prepared by a supercritical assisted-atomization (SAA) process, carbon dioxide as spraying medium and ethanol as solvent. The experimental results showed that the mean sizes of HPC particles decreased with decreasing the concentration of HPC solution, the optimal SAA parameters for smaller HPC particles were: saturator temperature of 353.2 K, saturator pressure of 8 MPa, precipitator temperature of 363.2 K, and the flow ratio of carbon dioxide to HPC solution of 0.8. The model drug in this study is a poorly water-soluble drug, beclometasone dipropionate (BDP). BDP-HPC composite particles were prepared using SAA process with the above optimal condition. The effect of different mass ratio of HPC to BDP (Z = HPC/BDP) on in vitro dissolution test of HPC/BDP composite particles was investigated in this study. In vitro dissolution test showed that the dissolution rate was enhanced because increasing durg wettability in conjunction with water-soluble HPC in BDP-HPC composite particles. Additionally, in vitro aerodynamic behavior of the water-soluble mannitol (MAN) particles was evaluated by cascade impactor. The mannitol particles were prepared using SAA process with different concentrations of MAN solution and different ethanol content in MAN solution. The effect of the morphology and the particles size of mannitol on powder flowability and de-agglomeration were investigated. In vitro aerosolization test showed that the powder flowability and de-agglomeration of the mannitol particles prepared at higher concentrations of MAN solution and ethanol contest in MAN solution could be enhanced.
Chang, Li-Wen, and 張力文. "Process conditions on the morphology and encapsulation capacity of spray-dried media-milled cellulose powder." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/92964649926042001545.
國立臺灣大學
食品科技研究所
103
In powder technology, control of particle morphology has received a lot of attention. The change of shapes has caused unprecedented chemical and physical properties that differ markedly from those of raw material. Spray dried technique is suggested to be a prospective way to produce various morphologies. Changing parameters of spray dryer is one of the strategy to control the morphology, including inlet temperature, solid concentration, gas flow rate, and so on. In this experiment, 3 different concentration (1% (w/w), 3% (w/w) and 5% (w/w)) of media milled cellulose and 4 different temperature (100℃, 115℃, 130℃ and 200℃) are chosen to spray dry. Physical properties and morphology of the cellulose spray dried powder would be analyzed. It shows that higher feed concentration produces larger spray dried particles. The particle size of 5% (w/w) feed concentration is two times as big as 1%(w/w). According to scanning electron micrograph, the spray dried cellulose powder at high concentration and high inlet temperature seems to form more spherical particle. It may relate to the evaporation rate, which affects the powder morphology, during drying. Higher inlet temperature and higher feed concentration result in faster evaporation, which leads to morphology variance. Also, the porosity of 5% feed concentration is the lowest, which infers to less open pore volume of the powder. Then, to assess the potential of media cellulose as a carrier, β-carotene is added into, according to the spray dried conditions mentioned above. It indicates that at 1% (w/w) feed concentration, the loading capacity is around 12-19%, while 5% (w/w) feed concentration is around 36-45%. The result implies that the particles at 130℃ inlet temperature and 5% (w/w) feed concentration show the highest loading capacity.
Hsu, Hong-Wen, and 徐鴻文. "Improvement of the digestion stability and the colorectal cancer cellular uptake of EGCG through microsphere encapsulation." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/45918158804999648719.
國立臺灣大學
食品科技研究所
104
EGCG is a polyphenol which has been well known for its potential to affect human health and disease such as obesity and matabolic syndrome. Recently, some researches suggest that EGCG can inhibit the proliferation of colorectal cancer cells and the expression of indoleamine 2, 3-dioxygenase(IDO) which is an immunosuppresive enzyme. Thus, EGCG can be considered as a potential agent for antitumor immunotherapy. However, ECGC would be rapidly oxidized and broken down into small compounds in intestinal tract. Thus, it is different to reach colon and be absorbed by colorectal cancer cells. To improve its digestion stability, we will encapsulate EGCG into liposome to prevent it from oxidation and hydrolysis catalyzed by enzymes. In addition, we plan to make our drug carriers selectively deliver EGCG to colon cancer cells. Because the surface charge of cancer cells will become more negative due to aberrant sialylation in the progress of cancerization, we can use cationic liposomes as drug carriers to increase its selectivity. There are some factors which will affect this selectivity such as the level of surface charge, the charge mobility and the membrane fluidity of drug carriers. So, we will go deep to investigate their effects on the selectivity of drug delivery. However liposomes cannot protect EGCG in intestinal tract because of lipases, we need to further encapsulate liposomes into pH responsive materials to avoid premature drug release. In our cellular drug uptake experiments, we find liposome can enhance drug delivery efficiency. Fluid phase liposomes have more drug deliver efficiency than gel phase and positive surface potential liposomes can deliver more drug than neutral & negative surface potential liposomes during the same period. But, if liposomes have high positive surface potential, gel phase liposome can deliver more drug than fluid phase liposome. We also evaluate the physicochemical characterizations of different liposomes and find fluid phase liposomes have better encapsulation efficiency and small average size. However, liposomes can not keep inside of EGCG in wet preservation but some of them can still keep their surface potential. In coating material dissolution experiments, we find that coating material need to have pH-responsive solubility and sustained release properties to help them to deliver drug to large intestine.
Wu, Sheng-Tsung, and 吳昇聰. "To Preparate the Encapsulation Epidermal Growth Factor in Microencapsulate Composed of Methyl Cellulose via Non-Solvent Emulsification Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/32869183817256079975.
亞洲大學
生物資訊學系碩士在職專班
98
In this study, using emulsion non-solvent phase separation,to f o r m t h e e n c a p s u l a t i o n E p i d e r m a l G r o w t h F a c t o r i n Microencapsulate Composed of Methyl Cellulose. The microcapsules to achieve the protection of epidermal growth factor activity, to prevent deactivation, and was released,to demonstrate the expected efficacy,and because dispersed in the microcapsules, and to increase contact surface area for the purpose. In this subject,to improve the microcapsules's structure and appearance was used the PVP K30 for good adhesion capacity, can easily be adsorbed on the surface of colloidal particles play the role of protective colloid, which demonstrate the film-forming so easy to adhesion between microcapsules to achieve the purpose of uniform release efficacy.Experiments on the preparation of the dried samples of microcapsules were f o l l o w t h e f r e e z e - d r y i n g a n d s p r a y d r y i n g m e t h o d . In this subject, to purchased the NIH/3T3 mouse embryonic fibroblast cells for non-toxic test,in the resultant,the Emulsion non-solvent can complete to release the medicinal properties.
McKinney, Jay Michael. "Intra-articular delivery of encapsulated human mesenchymal stem cells reduces osteoarthritis progression in a rat model." Thesis, 2017. https://hdl.handle.net/2144/23714.
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