Les écoulements de suspensions dans des milieux poreux sont particulièrement complexes, notamment à cause du couplage d’écoulements de cisaillement et d’écoulements élongationnels (Herzig, Leclerc et Goff, 1970). On les retrouve fréquemment dans les applications industrielles, l’une des applications principales se trouvant lors des opérations de production de pétrole et de gaz. Lors de la construction d'un puits, des additifs polymères anti perte de fluide empêchent à plusieurs étapes l'écoulement de fluide entre le puits et la formation de roche poreuse environnante. La perte de fluide est un problème grave si elle n’est pas maîtrisée ; elle s’ajoute alors au coût total des opérations et pourrait surtout avoir des conséquences néfastes pour l’environnement et les opérateurs. Parmi les technologies disponibles, des additifs polymères connus sous le nom d'additifs anti perte de fluide, tels que des microgels et des particules de latex, sont ajoutés aux fluides injectés pour limiter les pertes de fluide (généralement de l'eau) via un mécanisme de colmatage / blocage de pores du support poreux.Le comportement de blocage de beaucoup de ces additifs anti perte de fluide a été testé par des méthodes conventionnelles qui impliquent l'application d'une différence de pression élevée (typiquement 35-70 bars) sur le fluide formulé comprenant les additifs contre un filtre représentatif de la taille typique des pores de la formation (une grille métallique, de la céramique ou du papier filtre) et la mesure du volume de filtrat en fonction du temps. Cependant, ces méthodes standard ne permettent pas de comprendre le mécanisme sous-jacent de la dynamique de blocage des supports poreux. Par conséquent, une meilleure compréhension du mécanisme de blocage d’un support poreux par des additifs industriels anti perte de fluide est nécessaire.Dans ce travail, nous utilisons des suspensions de microgels réticulés chimiquement comme additifs anti perte de fluide et nous étudions leur comportement de blocage dans des milieux poreux modèles transparents. Nous utilisons des dispositifs à base de polydiméthylsiloxane (PDMS) comme modèle de support poreux permettant l'observation directe du processus de blocage couplée à des mesures quantitatives. Nous fabriquons des dispositifs microfluidiques de filtration frontale et de filtration latérale avec différentes tailles de pores afin de déterminer comment des paramètres tels que la mouillabilité de la surface, la concentration en particules, la taille des particules et le débit affectent la formation du gâteau de filtration.Nous présentons une méthode de contrôle de la taille des particules constituant les suspensions de microgels. Nous décrivons ensuite une approche pour préparer des suspensions à plus haute concentration et étudions la rhéologie des suspensions en fonction de la concentration en particules. De plus, nous présentons un procédé simple pour former un gâteau de filtration à partir de la suspension de microgels sur une membrane et estimons la perméabilité à l’eau du gâteau de filtration formé selon la loi de Darcy. / The flow of suspensions in porous media is a complex phenomenon due to the mechanisms involved such as both shear and extensional flows (Herzig, Leclerc, & Goff, 1970). Their use in industrial applications is quite extensive with one of the major applications being at various stages of oil and gas production operations. At several stages of a well construction, flow of fluid between the well and the surrounding porous rock formation is prevented thanks to the polymeric fluid loss control additives. Fluid loss is a severe problem if not controlled, which would add up to the total cost of operations and more importantly could have hazardous impacts on the environment or operators. Among several technologies industrially available, polymeric additives popularly known as fluid loss additives such as microgels and latex particles are added to the injected fluids to limit the loss of fluid (usually water) via the mechanism of pore clogging/jamming in porous media.Many of these fluid loss additives have been tested for their jamming behaviour by conventional methods which involve the application of a high pressure difference (typically 35-70 bars) on the formulated fluid comprising of the additives against a filter representative of the formation’s typical pore size (either a metallic grid, ceramic or filter paper) and the measurement of the filtrate volume versus time. However, these standard methods do not give any insight in understanding the underlying mechanism of jamming dynamics in porous media, hence, a better understanding of the mechanism of jamming in porous media by industrial fluid loss additives is needed.In this work, we use chemically cross-linked microgel suspensions as the fluid loss additive and study its jamming behaviour in transparent model porous media. We make use of polydimethylsiloxane (PDMS) devices as model porous media which allows direct observation of the jamming process coupled with quantitative measurements. We fabricate microfluidic devices for frontal flow filtration and lateral flow filtration with different pore sizes to see how parameters like surface wettability, particle concentration, particle size and flow rates affect the filter cake formation.We present a method of controlling the size of the microgel suspensions. We then describe an approach for preparing higher concentration suspensions and investigate the rheology of the suspensions as a function of concentration. Furthermore, we present a simple method of forming a filter cake of the microgel suspension on a supporting membrane and estimate the permeability of the filter cake formed for the flow of water using Darcy’s law.

Des émulsions particulièrement stables peuvent être formulées à l'aide de particules colloïdales (émulsions dites de Pickering). L'objectif de cette étude est d'accéder à la compréhension des mécanismes de stabilisation des interfaces, ainsi que du lien entre propriétés interfaciales et propriétés macroscopiques des émulsions. Dans ce cadre, la stratégie adoptée repose sur l'utilisation de particules colloïdales dont les caractéristiques peuvent être variées continûment à la fois en amont par la chimie de synthèse (variation de la mouillabilité, de la déformabilité) et in situ par un stimulus (pH, sel, température...). De plus, les émulsions stabilisées par de telles particules deviennent, elles aussi, sensibles aux stimuli et la déstabilisation des émulsions peut être déclenchée à la demande. Les mécanismes d'adsorption, les interactions entre particules aux interfaces et les propriétés résultantes des émulsions sont étudiés. L'établissement de concepts généraux régissant la stabilisation/déstabilisation des émulsions permet d'en contrôler, via la formulation ou le procédé (température, cisaillement), les propriétés d'usage. Enfin les émulsions stabilisées par des particules colloïdales peuvent être utilisées en tant que précurseurs dans la formulation de matériaux plus complexes : ceci est illustré par l'élaboration de capsules à libération thermostimulée.

The main goal of this work is design and synthesis of novel composite hydrogel-based core-shell microparticles and their application for fabrication of coatings, which provide the “inverse-switching” behaviour to the surface, namely, to become more hydrophobic in water environment. Since contact angle of heterogeneous surfaces is dependent on the nature and ratio of surface components, an increase of amount of more hydrophobic component on the surface will cause the reducing of surface wettability. It was suggested that core-shell particles having water-swellable hydrogel core and hydrophobic, but permeable for water shell when deposited on the hydrophilic substrate should increase the total amount of hydrophobic component on the surface when the cores of particles will swell in water. During the work different approaches to obtain freely dispersed and surface-immobilized core-shell particles with required structure were developed. Obtained particles were applied for preparation of coatings with ability to display “inverse-switching” behaviour. It was demonstrated that properly designed and properly prepared core-shell particles could be successfully used for creation of smart adaptive coatings having the ability to alter the surface properties upon changing of the environment.

Polyketides are natural products with complex chemical structures and immense pharmaceutical potential that are synthesized via secondary metabolic pathways. The in-vitro synthesis of these molecules requires high supply of building blocks such as acetyl Co-enzyme A, and cofactors (adenosine triphosphate (ATP). These precursor and cofactor are synthesized from respective soluble enzymes. Owing to the expensive nature of the enzymes, it is important to immobilize enzymes to improve the process economics by enabling multiple uses of catalyst and improving overall productivity and robustness. The polymer-based particles of nano and submicron size have become attractive material for their role in the life sciences. With the advances in synthetic protocols of the microgels and commercial availability of many of the monomers, it is feasible to tune the properties of the particles as per the process requirement. The core shell microgel with functional shell allows high loading of ligands onto the microgel particles due to increased availability of functional group on the outer surface. The aim of the thesis thus was to study biochemical reactions on the smart microgels support using single (acetyl CoA synthetase (Acs)) and dual (pyruvate kinase (Pk) and L-lactic dehydrogenase (Ldh)) enzyme/s systems. The study indicated that the enzyme immobilization significantly depends on the enzyme, conjugation strategy and the support. The covalent immobilization provides rigidity to the enzyme structure as in case of Acs immobilized on PNIPAm-AEMA microgels but at the same time leads to loss in enzyme activity. Whereas, in the case of covalent immobilization of Ldh on microgel showed improved in enzyme activity. On the other hand adsorption of the enzyme via ionic interaction provide better kinetic profile of enzymes hence the membrane reactor was prepared using PNIPAm-PEI conjugates for acetyl CoA synthesis. The better outcome of work with PNIPAm-PEI resulted in its further evaluation for dual enzyme system. This work is unique in the view that the immobilization strategies were well adapted to immobilize single and dual enzymes to achieve stable bioconjugates for their respective applications in precursor biosynthesis (Acetyl Co enzyme A) and co-factor dependent processes (ACoA and ATP). The positive end results of microgels as the support (particles in solution and as the thin film (membrane)) opens further prospective to explore these systems for other precursor biomolecule production.

Dans le lait on peut distinguer les protéines sériques et les caséines. Les protéines sériques sont des protéines globulaires qui se trouvent dans le sérum du lait et elles sont connues pour leurs propriétés fonctionnelles exceptionnelles. Quand une solution de protéines sériques est chauffée, elles perdent leur structure native et peuvent s'agréger. Elles forment des agrégats de différentes formes, tailles et densités : des cylindres, des agrégats fractals, des microgels et des agrégats fibrillaires. De l'autre côté, les caséines sont organisées dans des micelles de caséine d'un rayon environ 100-200 nm stabilisées par du phosphate de calcium colloïdal.Au cours de ce travail, nous avons cherché à comprendre comment les agrégats de protéines sériques pouvaient être utilisés en mélange avec les micelles de caséine pour obtenir et contrôler la texture de produits laitiers. Dans un premier temps, nous avons étudié le processus de « cold gelation » induit par ajout de calcium et/ou acidification d'agrégats et de microgels de protéines sériques seuls. Dans une deuxième partie, nous nous sommes intéressés à la fonctionnalité des agrégats dans les mélanges plus complexes avec les autres protéines laitières et en présence de minéraux. L'addition de petites quantités d'agrégats fractals dans des suspensions de micelles diminuait leur température critique de gélification, augmentait le module élastique et diminuait la synérèse des gels.Les agrégats de protéines sériques peuvent être utilisés pour modifier la viscosité des mélanges, comme gélifiant ou pour enrichir la teneur en protéine du milieu sans en augmenter la viscosité. / The proteins of milk can be divided into whey proteins and caseins. Whey proteins are compact globular proteins that are found in the aqueous phase of milk. They are well-known for their exceptional functional properties. Upon heating, individual whey proteins denature and aggregate, forming aggregates of different morphologies and sizes, such as strands, fractal aggregates, microgels and fibrillar aggregates, depending on the heating conditions. On the other hand, the caseins in milk are organized in complex protein units with a diameter of 100-200 nm called casein micelles stabilized by colloidal calcium phosphate (CCP).The current work is an endeavor to understand how whey protein aggregates might be used in mixtures with other dairy proteins, such as casein micelles, in order to get a particular texture in a dairy product. We first extended the understanding of so-called “cold gelation” of pure WPI aggregates induced by calcium and acidification and then studied how the aggregates work in more complex mixtures of proteins and minerals. Interestingly, addition of small amounts of fractal aggregates to suspensions of casein micelles has been demonstrated to decrease the critical gelation temperature, increase the elastic modulus and decrease the syneresis of the gels.The aggregates are to be used to modify the viscosity of dairy products, as a gelling agent and for protein enrichment. The properties of strands, fractal aggregates and microgels have been studied and compared. WPI aggregates might be considered as “clean label” texturizing ingredients that do not require approval from the European Food Safety Authority (EFSA).

No description available.

Composite materials formed from two or more functionally different materials offer a versatile avenue to create a tailored material with well defined traits. Within this dissertation research, multi-functional composites were synthesized based on organic and inorganic materials. The functionally of these composites was experimentally tested and a semi-empirical model describing the sedimentation behavior of these particles was developed. This first objective involved the fabrication of microcomposites consisting of titanium dioxide (TiO2) nanoparticles confined within porous, microgels of a thermo-responsive polymer for use in the photocatalytic treatment of wastewater. TiO2 has been shown to be an excellent photocatalyst with potential applications in advanced oxidative processes such as wastewater remediation. Upon UV irradiation, short-lived electron-hole pairs are generated, which produce oxidative species that degrade simple organic contaminants. The rapid sedimentation of these microcomposites provided an easy gravimetric separation after remediation. Methyl orange was used as a model organic contaminant to investigate the kinetics of photodegradation under a range of concentrations and pH conditions. Although after prolonged periods of UV irradiation (~8-13 hrs), the titania-microgels also degrade, regeneration of the microcomposites was straightforward via the addition of polymer microgels with no loss in photocatalytic activity of the reformed microcomposites. The second objective within this dissertation involved the systematic development of abrasive microcomposite particles containing well dispersed nanoparticles of ceria in an organic/inorganic hybrid polymeric particle for use in chemical mechanical polishing/planarization (CMP). A challenge in IC fabrication involves the defect-free planarization of silicon oxide films for successful multi-layer deposition. Planarization studies conducted with the microcomposites prepared in this research, yield very smooth, planar surfaces with removal rates that rival those of inorganic oxides slurries typically used in industry. The density and size of these ceria-microgel particles could be controlled by varying the temperature or composition during synthesis, leading to softer or harder polishing when desired.

The main goal of this work is design and synthesis of novel composite hydrogel-based core-shell microparticles and their application for fabrication of coatings, which provide the “inverse-switching” behaviour to the surface, namely, to become more hydrophobic in water environment. Since contact angle of heterogeneous surfaces is dependent on the nature and ratio of surface components, an increase of amount of more hydrophobic component on the surface will cause the reducing of surface wettability. It was suggested that core-shell particles having water-swellable hydrogel core and hydrophobic, but permeable for water shell when deposited on the hydrophilic substrate should increase the total amount of hydrophobic component on the surface when the cores of particles will swell in water. During the work different approaches to obtain freely dispersed and surface-immobilized core-shell particles with required structure were developed. Obtained particles were applied for preparation of coatings with ability to display “inverse-switching” behaviour. It was demonstrated that properly designed and properly prepared core-shell particles could be successfully used for creation of smart adaptive coatings having the ability to alter the surface properties upon changing of the environment.

<p>Injectable, in-situ gelling magnetic plum pudding hydrogel composites were fabricated by entrapping superparamagnetic iron oxide nanoparticles (SPIONs) and thermosensitive N-isopropylacrylamide (NIPAM)-co–N-isopropylmethacrylamide (NIPMAM) microgels in a pNIPAM-hydrazide/carbohydrate-aldehyde hydrogel matrix. The resulting composites exhibited significant, repeatable pulsatile release of 4 kDa FITC-dextran upon exposure to an alternating magnetic field. The pulsatile release from the composites could be controlled by altering the volume phase transition temperatures of the microgel particles (with VPTTs over 37°C corresponding to improved pulsatile release) and changing the microgel content of the composite (with higher microgel content corresponding to higher pulsatile release). By changing the ratio of dextran-aldehyde (which deswells at physiological temperature) to CMC-aldehyde (which swells at physiological temperature) in the composites, bulk hydrogel swelling and thus pulsatile release could be controlled; specifically, lower CMC-aldehyde contents resulted in little to no composite swelling, improving pulsatile release. <em>In vitro</em> cytotoxicity testing demonstrated that the composite precursors exhibit little to no cytotoxicity up to a concentration of 2000 µg/mL. Together, these results suggest that this injectable hydrogel-microgel composite hydrogel may be a viable vehicle for <em>in vivo</em>, pulsatile drug delivery.<strong></strong></p> / Master of Applied Science (MASc)

[ES] La ingeniería tisular ha evolucionado hacia el modelado de la fisiología humana in vitro. El microambiente de la médula ósea (BM) es también hogar de procesos malignos. El mieloma múltiple (MM) es una neoplasia hematológica caracterizada por proliferación y acumulación en la BM de células plasmáticas monoclonales. Los tratamientos han mejorado, sin embargo, sigue siendo incurable. Moléculas de la matriz extracelular como fibronectina (FN) o ácido hialurónico (HA) tienen un papel reconocido en la resistencia a fármacos (DR). La inadecuación de los modelos preclínicos bidimensionales es una de las bases del problema de DR. Se han intentado diferentes enfoques in vitro, sin embargo, se basan en hidrogeles y andamios celulares diseñados para células adherentes, mientras que las células de MM presentan crecimiento en suspensión. El objetivo principal de esta Tesis es desarrollar, optimizar y validar una plataforma de cultivo 3D, denominada microgel, basada en microesferas en un medio líquido y que coexisten con células de MM creciendo dinámicamente en suspensión. Se desarrollaron y caracterizaron diferentes microesferas con diferentes funcionalizaciones. Optimizamos un protocolo de polimerización en suspensión para la obtención de microesferas a base de acrilatos con dos composiciones diferentes (presencia (10%) o ausencia (0%) de ácido acrílico (AA)) i dos distribuciones de tamaño diferentes (< 60 y > 70 ¿m). La FN se adsorbió en la superficie de la microesfera, mientras que el HA, colágeno I y diferentes secuencias peptídicas se injertaron covalentemente. Se modificaron las microesferas comerciales Cytodex 1 para adaptar sus características a la plataforma. Se utilizaron técnicas capa por capa (LbL) para introducir HA y sulfato de condroitina (CS) en su superficie. Por tanto, se ha generado un amplio repertorio de microesferas para desarrollar microgeles. Se optimizaron y validaron las condiciones de cultivo para la plataforma de microgel. Las condiciones óptimas se establecieron como 150 rpm de velocidad de agitación utilizando un agitador orbital y microesferas de < 60 ¿m. Los microgeles con diferentes composiciones y funcionalizaciones permitieron una buena proliferación de las líneas RPMI8226, U226 y MM1.S. Todos los sistemas respetaron el patrón de crecimiento en suspensión, factor que ha demostrado ser clave para su buen desempeño en cultivo 3D. En estudios iniciales de DR, la línea celular RPMI8226 cultivada en microgeles que contenían AA mostró una resistencia significativamente mayor a la dexametasona que sus cultivos en suspensión. Y las líneas RPMI8226, U226 y MM1.S cultivadas en microgeles que contenían AA mostraron una resistencia significativamente mayor a bortezomib que sus cultivos en suspensión. Por lo tanto, la presencia de AA en la matriz polimérica mostró un efecto positivo en la generación de DR in vitro y requerirá más estudios. Se ha validado la reducción de escala del sistema para trabajar con volúmenes más pequeños de microesferas y números reducidos de células, lo que es de gran relevancia para su traslación clínica. Finalmente, se han realizado cultivos preliminares con la línea celular RPMI8226 en los microgeles basados en Cytodex 1. Las microesferas de Cytodex 1 sin modificación tuvieron un efecto negativo sobre la viabilidad de las células de MM. La modificación mediante LbL con los pares quitosano/CS y quitosano/HA aumentó la viabilidad y proliferación. Sin embargo, estos sistemas no respetaron el carácter no adherente de las células MM. Hemos desarrollado y validado un novedoso sistema de cultivo basado en un medio 3D semisólido definido por microesferas y células de MM especialmente diseñado para células en suspensión. Este sistema constituye una herramienta versátil que debe explorarse más a fondo para el cultivo 3D de neoplasias hematológicas y para estudios de resistencia a fármacos in vitro. / [CAT] L'enginyeria tissular ha evolucionat cap al modelat de la fisiologia humana in vitro. El complex microambient de la medul·la òssia (BM) és també llar d'alguns processos malignes. El mieloma múltiple (MM) és una neoplàsia hematològica caracteritzada per una proliferació i acumulació a la BM de cèl·lules plasmàtiques monoclonals. Els tractaments han millorat, no obstant, el MM segueix sent incurable. Molècules de la matriu extracel·lular com fibronectina (FN) o àcid hialurònic (HA) tenen un paper reconegut en la generació de resistència a fàrmacs (DR) en MM. La inadequació dels models preclínics bidimensionals és una de les bases del problema de DR. Per això, s'han intentat diferents aproximacions in vitro, tanmateix es basen en hidrogels i andamis cel·lulars dissenyats per a cèl·lules adherents, mentre que les cèl·lules de MM presenten creixement en suspensió. L'objectiu principal d'aquesta Tesi és desenvolupar, optimitzar i validar una plataforma de cultiu 3D, denominada microgel, basada en microesferes en un medi líquid i que coexisteixen amb cèl·lules de MM que creixen dinàmicament en suspensió. S'han produït i caracteritzat diferents microesferes amb diferents funcionalitzacions. S'ha optimitzat un protocol de polimerització en suspensió per a l'obtenció de microesferes d'acrilats amb dues composicions diferents (presència (10%) o absència (0%) d'àcid acrílic (AA)) i amb dos distribucions de diàmetres diferents (< 60 y > 70 ¿m). La FN es va adsorbir, mentre que el HA, el col·lagen I i diferents seqüències peptídiques es van unir covalentment. S'han modificat microesferes comercials Cytodex 1 per tal d'adaptar les seves característiques a la plataforma del microgel. Mitjançant tècniques capa a capa (LbL) s'han introduït HA i sulfat de condroïtina (CS) a la seua superfície. Per tant, s'ha generat un ampli repertori de microesferes per desenvolupar microgels. Es van optimitzar i validar les condicions de cultiu per a la plataforma de microgel. Les condicions òptimes de cultiu es varen establir com a 150 rpm de velocitat d'agitació utilitzant un agitador orbital i microesferes de < 60 ¿m. Els microgels amb diferents composicions i funcionalitzacions van permetre una bona proliferació de les línies RPMI8226, U226 i MM1.S. Tots els sistemes van respectar el patró de creixement en suspensió, factor que ha demostrat ser clau per al seu bon rendiment en cultius 3D. En estudis inicials de DR línia cel·lular RPMI8226 cultivada en microgels que contenien AA va mostrar una resistència significativament major a la dexametasona que els seus cultius en suspensió convencionals. Línies RPMI8226, U226 y MM1.S cultivades en microgels que contenien AA mostraren una resistència significativament major a bortezomib que els seus cultius en suspensió convencionals. Per tant, la presencia d'AA a la matriu polimèrica de les microesferes va mostrar un efecte positiu en termes de generació de DR in vitro, cosa que requerirà estudis futurs. S'ha validat la reducció de l'escala del sistema per treballar amb volums més petits de microesferes i menys cèl·lules, el que és de gran rellevància per a la seva translació clínica. Finalment, s'han realitzat cultius preliminars amb la línia cel·lular RPMI8226 en els microgels basats en les Cytodex 1. Les microesferes de Cytodex 1 sense modificar van mostrar efecte negatiu sobre la viabilitat de les cèl·lules de MM. La modificació mitjançant LbL amb els parells quitosà/CS i quitosà/HA va augmentar la viabilitat i proliferació de cèl·lules MM. No obstant, aquests sistemes no respectaren el caràcter no adherent de les cèl·lules de MM. S'ha desenvolupat i validat un nou sistema de cultiu cel·lular basat en un medi 3D semisòlid definit per microesferes i cèl·lules de MM, especialment dissenyat per a cèl·lules no adherents. Aquest sistema constitueix una eina versàtil que ha de ser explorada per al cultiu 3D de neoplàsies hematològiques i per a estudis de resistència a fàrmacs in vitro. / [EN] Tissue engineering has evolved towards modeling of human physiology in vitro. The bone marrow (BM) microenvironment is likewise the home of some malignant processes. Multiple myeloma (MM) is a hematological neoplasia characterized by proliferation and BM accumulation of monoclonal plasma cells. Treatments have improved; however, MM remains incurable. Extracellular matrix molecules such as fibronectin (FN) or hyaluronic acid (HA) have a recognized role in drug resistance (DR). The inadequacy of two-dimensional preclinical models is one cause of the DR problem, different in vitro approaches have been developed, however, all these studies are based on hydrogels and scaffolds designed for adherent cells while MM cells are suspension growing cells. The main objective of this Thesis is to develop, optimize and validate a 3D culture platform, termed as microgel, based on microspheres suspended in a liquid media and coexisting with MM cells growing dynamically in suspension. Different microspheres with different functionalities were developed and characterized. We optimized a suspension polymerization protocol for the obtention of acrylates-based microspheres with two different compositions: with presence (10%) or absence (0%) of acrylic acid (AA). We obtained two different size distributions (< 60 and > 70 ¿m). FN was adsorbed on microsphere surface, while HA, collagen I and different peptide sequences were covalently grafted. Commercial Cytodex 1 microspheres were modified to adapt their characteristics to the microgel platform. Layer-by-layer (LbL) technics were used to introduce HA and chondroitin sulfate (CS) on Cytodex 1 surface. Therefore, a wide repertoire of microspheres has been generated to develop microgels. The culture conditions for the microgel platform were optimized and validated. Agitation is needed to keep microspheres and cells in suspension. Optimal culture conditions were 150 rpm of stirring speed using orbital shaker and < 60 ¿m diameter microspheres. Microgels with different compositions (0% AA, 10% AA) and functionalizations (none, HA, FN, collagen 1 and peptide sequences) allowed good proliferation of RPMI8226, U226 and MM1.S cells under 3D conditions. All the 3D systems respected the suspension growth pattern which appears as key factor for their good performance in 3D culture. In the initial DR studies, we found that MM cell line RPMI8226 cultured in microgels containing AA showed significantly higher resistance to dexamethasone than their conventional suspension cultures. And that MM cell lines RPMI8226, U226 and MM1.S cultured in microgels containing AA showed significantly higher resistance to bortezomib than their conventional suspension cultures. Thus, AA in the polymeric microsphere matrix showed a positive effect on the generation of DR in vitro and will require further studies. The scale-down of the system to work with smaller volumes of microspheres and reduced cell numbers has been validated, this is of great relevance for their clinical application. Finally, preliminary cultures with the cell line RPMI8226 have been performed with the Cytodex 1-based microgels. Cytodex 1 microspheres without modification had a negative effect on MM cells viability. LbL modification with the pairs chitosan/CS and chitosan/HA increased MM cells viability and proliferation. However, these systems did not respect the non-adherent character of MM cells. We have developed and validated a novel cell culture system based on a semi-solid 3D media defined by microspheres and MM cells which is specially designed for cells in suspension. It represents a versatile tool that should be further explored for the 3D culture of hematological malignancies and drug resistance studies in vitro. / Me gustaría agradecer al Servicio de Microscopía de la UPV y a sus técnicos por su valiosa ayuda con las técnicas de microscopía electrónica, a la Agencia Estatal de Investigación (proyecto PID2019-106099RB-C41 / AEI / 10.13039/501100011033) y al Ministerio de Ciencia, Innovación y Universidades (ayuda predoctoral FPU17/05810) que han financiado esta Tesis. / Clara Trujillo, S. (2022). Development of a 3D in Vitro Disease Model for Multiple Myeloma [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/186054