Many important therapeutic agents are associated with significant undesired side effects which often limit treatment duration and dosing. Specifically, most major classes of antitumor chemotherapeutics have deleterious effects on cell division and DNA synthesis throughout the body due to systemic biodistribution. Engineering systems for controlled drug delivery allows for improved quality of life during treatment; as well as higher localized therapeutic concentrations by isolating toxic drugs used in many diseases to specific physiological compartments. An important drug delivery strategy for controlled release of therapeutics is based on responsive polymer matrices, which undergo swelling transitions in response to environmental stimuli. Biologically relevant factors which may trigger the release of therapeutics from responsive polymers include pH, ionic strength, and temperature. Temperature responsive polymers integrated into a composite system with metal nanoparticles allow for on demand drug release via an externally-applied optical or magnetic energy source. The intent of this work was to develop a temperature-responsive drug delivery platform for controlled therapeutic release, as well to expand the toolbox for rational design of responsive hydrogel nanoparticles intended for therapeutic delivery. Temperature-responsive hydrogels were synthesized and examined in the form of nanoparticles and bulk polymer networks. These materials are based on interpenetrating polymer networks (IPNs) of polyacrylamide (PAAm) and poly(acrylic acid) (PAA), which exhibit a positive volume swelling response with respect to temperature. Since this system responds to pH, ionic strength, and temperature, these IPNs were characterized over a wide range of solution conditions. Critical synthesis parameters needed to optimize thermal responses for specific solution conditions were identified, as were the specific effects of pH and ionic strength on network swelling and stability. The reverse emulsion process used to synthesize IPN nanoparticles was characterized to determine how particle growth proceeds during preparation. To enhance biocompatibility, IPN nanoparticles were surface-modified with a corona of poly(ethylene glycol) to reduce protein adsorption, a common strategy to improve in vivo performance. Due to the large amounts of surfactants employed in the preparation of IPN nanoparticles, purification methods needed to improve safety of IPN nanoparticles were optimized, and studied in vitro to ensure cellular compatibility. / text

Advances in medical treatment are leading away from generalized care towards intelligent systems or devices which can sense and respond to their environment. With these devices, the burden of monitoring and dosing for treatment can be removed from the doctor (or the patient) and be placed on the device itself. Implicit closed-loop control systems will allow the device to respond to its environment and release therapeutic agent in response to a specific stimulus. Environmentally responsive hydrogels show great promise in being incorporated in such an intelligent device, such as pH-responsive hydrogels which can swell and deswell in response to changes in the pH of the media. Thus, pH changes can be exploited for controlled and intelligent drug delivery when used in combination with these pH-responsive hydrogels. In this work, heterogeneous, thermal-redox initiated free-radical polymerizations were developed to synthesize novel pH-responsive hydrogels, microparticles, and nanogels. The specific disease of interest was type I diabetes, which requires daily doses of insulin both at a basal amount and either a postprandial or preprandial bolus in order to maintain blood glucose levels within safe limits. To allow pH-responsive hydrogels to be sensitive to glucose, glucose oxidase was incorporated which oxidizes glucose to gluconic acid. A novel inverse-emulsion polymerization method was developed for the synthesis of poly[2-(diethylaminoethyl methacrylate)-grafted-polyethylene glycol monoethyl ether monomethacrylate] (P(DEAEM-g-PEGMMA)) nanogels (100-400 nm) for intelligent insulin delivery. The new polymerization method allowed the incorporation of hydrophilic components, such as glucose oxidase and catalase, as well as PEG surface tethers of lengths 400 Da up to 2000 Da. Surface tethers successfully decreased the surface charge of the nanogels. Insulin loading and release was determined for microparticles which were able to imbibe substantial amounts of insulin from solution when swollen, entrap the insulin when collapsed, and then release the insulin in response to either a pH or glucose stimulus. / text

abstract: Many therapeutics administered for some of the most devastating illnesses can be toxic and result in unwanted side effects. Recent developments have been made in an alternative treatment method, called gene therapy. Gene therapy has potential to rectify the genetic defects that cause a broad range of diseases. Many diseases, such as cancer, cystic fibrosis, and acquired immunodeficiency (AIDS) already have gene therapy protocols that are currently in clinical trials. Finding a non-toxic and efficient gene transfer method has been a challenge. Viral vectors are effective at transgene delivery however potential for insertion mutagenesis and activation of immune responses raises concern. For this reason, non-viral vectors have been investigated as a safer alternative to viral-mediated gene delivery. Non-viral vectors are also easy to prepare and scalable, but are limited by low transgene delivery efficacies and high cytotoxicity at effective therapeutic dosages. Thus, there is a need for a non-toxic non-viral vector with high transgene efficacies. In addition to the hurdles in finding a material for gene delivery, large-scale production of pharmaceutical grade DNA for gene therapy is needed. Current methods can be labor intensive, time consuming, and use toxic chemicals. For this reason, an efficient and safe method to collect DNA is needed. One material that is currently being explored is the hydrogel. Hydrogels are a useful subclass of biomaterials, with a wide variety of applications. This class of biomaterials can carry up to a thousand times their weight in water, and are biocompatible. At smaller dimensions, referred to as micro- and nanogels, they are very useful for many biomedical applications because of their size and ability to swell. Based on a previously synthesized hydrogel, and due to the advantages of smaller dimension in biomedical applications, we have synthesized aminoglycoside antibiotic based nanogels and microgels. Microgels and nanogels were synthesized following a ring opening polymerization of epoxide-containing crosslinkers and polyamine-containing monomers. The nanogels were screened for their cytocompatibilities and transfection efficacies, and were compared to polyethylenimine (PEI), a current standard for polymer-mediated transgene delivery. Nanogels demonstrated minimal to no toxicity to the cell line used in the study even at high concentrations. Due to the emerging need for large-scale production of DNA, microgels were evaluated for their binding capacity to plasmid DNA. Future work with the aminoglycoside antibiotic-based nanogels and microgels developed in this study will involve optimization of nanogels and microgels to facilitate in better transgene delivery and plasmid DNA binding, respectively. / Dissertation/Thesis / M.S. Chemical Engineering 2014

Current treatment for posterior segment ocular diseases requires intravitreal injections administered every 4-6 weeks. The potential for siRNA to be used to treat these diseases is extremely attractive due to the specificity of these molecules and their potential for making long term changes to the expression patterns of the cells. Due to physiological recognition, however siRNA undergoes rapid degradation upon application. The development of cationic nanogels using polymeric “smart” biomaterials with degradable components to transport siRNA is described. pH – sensitive N, N dimethylaminoethyl methacrylate (DMAEMA) was crosslinked with thermo-sensitive diethylene glycol methacrylate (DEGMA), by free radical emulsion-precipitation polymerization. Size, charge and morphology were analyzed to assess potential as a nanovehicle. Through modification of the particle composition, cationic nanogels, determined by zeta potential, with sizes of approximately 160 nm confirmed with dynamic light scattering (DLS), were synthesized. A composition of 55:45 (DEGMA:DMAEMA); a size and charge ideal for cellular uptake. These particles had minimal impact on cell proliferation and exhibited spherical morphology when imaged by TEM at physiological pH. The structure was maintained between pH 3.5-9. Sensitivity to pH was shown by DLS through swelling at physiological pH, which may be useful can be taken advantage of in future studies for loading and release. Degradation with a reducing agent was shown using gel permeation chromatography, DLS and turbidity analysis. The results suggest this formula will undergo degradation in the cell. Reducing environments mimicking intracellular conditions that promoted degradation of the crosslinker showed enhanced release of dexamethasone phosphate as a model drug. Ongoing work is focused on examining gene silencing using these formulations. / Thesis / Master of Applied Science (MASc)

Les nanogels sont de bons candidats pour la délivrance d’actifs. Ces réseaux de polymères réticulés et de taille nanométrique, sont gonflés d’eau. Ils sont donc capables d’encapsuler une protéine à l’intérieur de leurs pores et de la libérer en fonction de l’état de gonflement du réseau. Cet état peut être modulé par la densité de réticulation du réseau ou par l’application d’un stimulus externe tel que le pH, la température ou encore une biomolécule telle que le glucose. Ainsi, les nanogels sensibles au glucose se présentent comme des candidats idéaux pour administrer l’insuline de façon asservie à la glycémie. Afin de satisfaire aux critères de biocompatibilité et de biorésorption des vecteurs, nous avons choisi de développer des nanogels à base de polysaccharide, en particulier à base d’acide hyaluronique (HA). Ceux-ci sont obtenus par réticulation du HA, préalablement modifié par des fonctions réticulables telles que les méthacrylates, dans des nanogouttes d'émulsion eau-dans-huile. Des nanogels de taille et de porosité modulables ont été synthétisés grâce à un bon contrôle 1) de la modification chimique des précurseurs par des fonctions réticulables (taux de méthacrylation), 2) de l’émulsion matricielle (taille, stabilité), 3) des conditions de réticulation par photopolymérisation gouvernant le taux de conversion des méthacrylates. Ce savoir-faire a ensuite été appliqué à la synthèse de nanogels modifiés par des dérivés de l’acide phénylboronique, ligand du glucose, afin d’obtenir des matériaux dont le taux de gonflement varie en fonction de la glycémie. L’intérêt applicatif de ces objets a été évalué vis-à-vis des propriétés d’encapsulation de l’insuline, de dégradabilité enzymatique, et de biocompatibilité. / Nanogels are an attractive class of delivery systems. These soft particles, made of highly swollen polymer network, can physically entrap a drug and release it at a rate depending on its diffusion though the network. Therefore, any change in the swelling degree can trigger the release kinetics. This parameter can be tuned by modifying the density of cross-links in the gel matrix or by changing the environmental conditions such as pH, temperature or analyte such as glucose. Thus, glucose-responsive nanogels are good candidates to be used as self-regulated systems for insulin delivery. To fulfill both biocompatibility and biodegradability criteria, our attention has been focused on the design of new nanogels made of polysaccharides, in particular made of hyaluronic acid (HA), as a main constituent. HA was at first covalently modified with polymerizable methacrylate functions and confined in nanoreactors during photopolymerization using water-in-oil miniemulsions as template. Biodegradable nanogels with a well-defined size and various cross-linking degrees were thus achieved, thanks to a good control of 1) the chemical modification of HA with methacrylates (degree of methacrylation) 2) the emulsion template (size, stability), 3) the photopolymerization conditions which governed the conversion rate of the polymerization. Further modification of the polysaccharide with phenylboronic acid as a glucose-sensitive group yielded nanogels whose swelling behavior could vary as a function of glucose concentration. These systems were further studied as insulin delivery systems. Moreover, their biodegradability, stability and biocompatibility were assessed.

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

Hidrogéis (redes poliméricas tridimensionais capazes de absorver grandes quantidades de água) micro e nanoestruturados têm grande potencial como biomateriais em aplicações tais como dispositivos de liberação de fármacos e agentes embólicos. Neste trabalho foram estudadas técnicas de produção desses hidrogéis micro e nanoestruturados à base de poli(N-vinil-2-pirrolidona) (PVP), a partir da reticulação do polímero através de reações de Fenton, foto-Fenton e fotólise direta. Microgéis de PVP foram obtidos a partir da reticulação de esferas obtidas por eletropulverização ou de gotículas de solução aquosa do polímero em emulsão a/o. No primeiro caso, obtiveram-se partículas que, quando reticuladas com a reação de Fenton durante o processo de eletropulverização, apresentaram formato indefinido. No segundo caso, foram obtidas microesferas de PVP, tanto pela reticulação com a reação de Fenton, obtendo-se partículas menores da - ordem de 1 µm - como com a reação de foto-Fenton, que gerou partículas maiores de - 34 µm. Hidrogéis sub-micrométricos foram obtidos a partir da formatação em vesículas de lecitina e reticulados por meio da reação de foto-Fenton. Essas vesículas foram capazes de encapsular grande quantidade de polímero, mesmo sendo este de alta massa molar média. Os hidrogéis sintetizados apresentam estreita distribuição de diâmetro, porém sem forma definida e com baixo índice de intumescimento. Por fim, nanogéis (nanopartículas de hidrogéis) foram obtidos da reticulação de PVP com a reação de Fenton (Fe2+ na presença de H2O2), utilizando como sistema formatador o interior aquoso de micelas reversas de CTAB. Os nanogéis assim formados são esféricos e apresentam propriedades interessantes, como fator de intumescimento de até 6000, inédito na literatura, que os colocam na categoria de hidrogéis superabsorventes. Além disso, o intumescimento é passível de controle tanto pela remoção dos íons Fe3+ complexados, como pela acidez e composição iônica do meio. Durante o desenvolvimento da síntese dos nanogéis foi possível estudar a influência do Fe3+ na estruturação da solução polimérica e do hidrogel. Além disso, a cinética da reticulação do polímero dentro das micelas e uma comparação entre dois sistemas micelares diferentes na formatação do nanogel foram analisados. A análise do produto também permitiu constatar a baixa toxicidade do material obtido com testes in vitro utilizando macrófagos e fibroblastos. / Micro and nanostructured hydrogels (three-dimensional polymeric networks capable of absorbing large amounts of water) have great potential as biomaterials in applications such as drug delivery devices and embolic agents. In this work techniques to produce micro and nanostructured hydrogels from poly(N-vinyl-2-pyrrolidone) (PVP) were studied from various crosslinking reactions like Fenton, photo-Fenton and direct photolysis. PVP microgels were obtained from crosslinking of polymer spheres obtained by electrospraying a polymer solution or from droplets of aqueous polymer solution in w/o emulsion. In the first case, particles were obtained that, when crosslinked with the Fenton reaction, showed undefined morphology. In the second case, spherical PVP hydrogel microparticles were obtained, which were formed by crosslinking with Fenton reaction, resulting in smaller particles - about 1µm - while with photo-Fenton reaction it generated larger particles - about 34 µm. Sub-micrometric hydrogels were obtained from lecithin vesicles as formatting system through crosslinking with photo-Fenton reaction. These vesicles were able to encapsulate large amounts of polymer, in spite of its high average molecular weight. Hydrogels synthesized by this method are formless, with narrow diameter distribution and low swelling properties. Finally, nanogels (hydrogel nanoparticles) were obtained from crosslinking of PVP by the Fenton reaction (Fe2+ in presence of H2O2), using aqueous pool of CTAB reverse micelles as formatting system. The thus formed nanogels are spherical and present interesting properties such as swelling ratio of 6000, a level unreported in literature, which classifies them as superabsorbent hydrogels. Moreover, the swelling is susceptible to control either by the removal of complexed Fe3+ ions or by acidity and ionic composition of the medium. During the nanogels synthesis development, the influence of Fe3+ in the arrangement of the polymer solution and of the hydrogel was studied. Morever, the polymer crosslinking kinetics inside the micelles and a comparison between two different micellar systems in formatting of nanogel were analyzed. The product analysis also revealed low toxicity of the obtained material by in vitro experiments using macrophages and fibroblasts.

Hydrogel micro- and nanoparticles (microgels and nanogels) are a promising class of drug delivery vehicles. Composed of hydrophilic polymers arranged into a cross-linked network structure, nanogels show several attractive features for the delivery of macromolecule therapeutics. For instance, the hydrated, porous internal cavity of the nanogel may serve as a high capacity compartment for loading macromolecules, whereas the periphery of the nanogel may be used as a scaffold for conjugating cell-specific targeting moieties. This dissertation presents recent investigations of nanogels as targeted delivery vehicles for oligonucleotides to cancer cells, while exploring new nanogel chemistries that enable future in vivo applications. For instance, synthetic efforts have produced particles capable of erosion into low molar mass constituents, providing a possible mechanism of particle clearance after repeated administration in vivo. In another example, the microgel network chemistry was tuned to promote the encapsulation of charged proteins. In parallel with those synthetic efforts, new light scattering methodologies were developed to accurately quantify the particle behaviors (e.g. loading, erosion). Using multiangle light scattering (MALS), changes in particle molar mass and radius were measured, providing a quantitative and direct approach for monitoring nanogel erosion and macromolecule encapsulation. The new particle chemistries demonstrated, together with enabling light scattering methods, will catalyze the development of improved delivery vehicles in the near future.

This thesis studies the formation of mobile and surface-bound electric charges in nonpolar liquids. Unlike aqueous media with their natural abundance of charged species, liquids of low dielectric constant do not readily accommodate charges, but can do so in the presence of certain surfactant additives. Surfactant-mediated charging in nonpolar oils has long been exploited industrially, but the underlying charging mechanisms are far from understood. The present work seeks clarification by comparing the effect of ionic and nonionic surfactants on the conductivity of nonpolar solutions and the electrophoretically observable surface charge of suspended polymer particles. Both types of surfactant are found to generate mobile ions in solution as well as particle charge; and in the more surprising case of nonionic surfactants, the occurrence of particle charge and screening ions is confirmed independently by measurements of the electrostatic particle interaction energy. A systematic variation of the particle material and functionalization, the residual water content, and the surfactant concentration above and below the critical micelle concentration provides insights about the possible charging pathways. Reverse surfactant micelles are explored not only as charging agents, but also as reactors and templates for the synthesis of novel nanogels with promise for drug delivery. Synthesis via copper-free Click chemistry is shown to allow for better control of the particle size than a more conventional polymerization scheme, while avoiding metal catalysts and free radicals that are considered hazardous for most biomedical applications.

Actuellement, la mise au point de systèmes de vectorisation d'agents chimio-thérapeutiques performants fait l'objet d'une intense recherche. Les nanoparticules en particulier sont étudiées, car elles permettent de solubiliser des molécules hydrophobes en milieux aqueux tout en diminuant leur toxicité et leur dégradation. Toutefois, le devenir à long terme des nanoparticules est un paramètre important qu'il faut considérer dans la conception de ces nanovecteurs. Pour cette raison, le développement de nanoparticules auto-assemblées constituées de copolymères à bloc entièrement biocompatibles, biodégradables et aux propriétés de libération contrôlée est recommandé. Dans cette perspective, nous avons étudié les propriétés d'auto-organisation de copolymères greffés amphiphiles de type chitooligosaccharide-grafted-polycaprolactone. Le premier chapitre révèle l'utilisation de l'aniline et de son dérivé alcyne comme un outil efficace pour l'amination réductrice de chitooligosaccharides. Dans le second chapitre, différentes familles de polycaprolactone avec des fonctions azide latérales sont décrites. Le troisième chapitre traite du couplage par chimie " click " de chaque bloc ainsi que de la caractérisation physico-chimique des nanoparticules en solution aqueuse. La réticulation de ses particules a permis d'obtenir les nanogels finaux. Pour conclure, des tests d'encapsulation et de libération contrôlée de la Doxorubicine (avec ou sans ajout de glutathion) ont été effectués