Orientador: Ana Flávia Nogueira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T23:28:35Z (GMT). No. of bitstreams: 1 Freitas_IvoBernardide_M.pdf: 1962051 bytes, checksum: f313acbe4cbb5d4065bb7bb26e42e3ac (MD5) Previous issue date: 2013 / Resumo: Neste trabalho foram estudados filmes finos multicamadas baseados em nanopartículas inorgânicas e um polieletrolito inerte, depositados pela técnica layer-by-layer (LbL). O trabalho está dividido em três partes: 1) Síntese e caracterização de nanopartículas de CdSe; 2) Montagem de filmes LbL baseados no cloreto de poli(diallildimetilamônio) (PDDA) e nanopartículas de CdSe e TiO2; e 3) Estudos fotoeletroquímicos dos filmes. As nanopartículas sintetizadas foram caracterizadas por espectroscopia de absorção no ultravioleta-visível (UV-vis), espectroscopia de fluorescência, microscopia eletrônica de alta resolução (HRTEM) e difração de raios-X (DRX). As partículas sintetizadas não apresentaram a mesma qualidade daquelas reportadas pela literatura, apresentando grande número de defeitos e larga distribuição de tamanhos. Como não foi possível a separação adequada de nanopartículas de diferentes tamanhos, optou-se por dar continuidade ao trabalho com somente um tamanho obtido. Foram fabricados filmes contendo TiO2 e PDDA, filmes contendo CdSe e PDDA e filmes contendo TiO2, CdSe e PDDA. Estes foram caracterizados por espectroscopia de absorção no UV-vis, espectroscopia de fluorescência, microscopia de força atômica (AFM) e espectroscopia Raman. Os filmes apresentaram um crescimento linear a cada bicamada realizada. Visando melhorar a qualidade dos filmes fabricados um tratamento com brometo de hexadeciltrimetilamonio (CTAB) foi utilizado. Os filmes de nanopartículas de CdSe com tratamento apresentaram uma quantidade de defeitos menor em relação aos filmes sem tratamento. Os fotoeletrodos foram caracterizados por medidas de fotocorrente em função do tempo (fotocronoamperometria). Os filmes contendo TiO2 e PDDA apresentaram valores de fotocorrente, entre 2 e 50 mA cm, exibindo comportamento de semicondutor do tipo-n. Ja os filmes contendo CdSe e PDDA apresentaram valores baixos de fotocorrente (2 mA cm). Mesmo após a realização do tratamento com CTAB e a incorporação de nanopartículas de TiO2 nos filmes não observou-se uma significante alteração nestes valores / Abstract: In this work, multilayered thin films based on inorganic nanoparticles and an inert polyelectrolyte deposited by the layer-by-layer technique were studied. The work was divided in three parts: 1) Synthesis and characterization of CdSe nanoparticles; 2) Assembly of LbL films based in poly(diallyldimethylammonium chloride) (PDDA) , CdSe and TiO2 nanoparticles; 3) Photoelectrochemical studies of the films. The nanoparticles synthetized were characterized by absorption spectroscopy, fluorescence spectroscopy, high resolution electron microscopy (HRTEM) and X-ray diffraction. The synthesized nanoparticles didn¿t show the same quality of those reported in literature. They presented a large number of defects and a broad size distribution. As it was not possible to obtain nanoparticles of different sizes, we decided to continue the work with only one nanoparticle size. Films were fabricated using CdSe and PDDA, TiO2 and PDDA, and CdSe, PDDA and TiO2. They were characterized by absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy (AFM) and Raman spectroscopy. The films showed a linear increase to each bilayer performed. In order to improve the films quality containing CdSe nanoparticles, a treatment using hexadecyltrimethylammonium bromide (CTAB) was performed. As a result, the treated films showed a smaller number of defects compared to the films without treatment. The photoelectrodes were characterized by measurements of photocurrent versus time (photochronoamperometry). The films containing TiO2 and PDDA showed appreciable values of photocurrent, between 2 and 50 mA cm, exhibiting an n-type semiconducting behavior. However, the films containing CdSe and PDDA showed low photocurrent values (2 mA cm). Even after the treatment with CTAB and the incorporation of the TiO2 nanoparticles in the films, no remarkable improvement in the photocurrent values was observed / Mestrado / Quimica Inorganica / Mestre em Química

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15613号 / 工博第3302号 / 新制||工||1498(附属図書館) / 28140 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 辻井 敬亘 / 学位規則第4条第1項該当

Le relargage contrôlé est un enjeu industriel auquel l'encapsulation peut répondre. Une méthode prometteuse pour fabriquer des micro-capsules consiste à déposer couche après couche des polymères à la surface de goutte d'huiles ou de bulles d'air. Cette thèse a pour objet ces assemblages en multicouches de polymères aux interfaces liquides. A partir d'expériences menées sur des interfaces modèles entre deux fluides non miscibles et leur modélisation, nous avons étudié l'effet des interactions à l'échelle des chaînes de polymère sur les propriétés rhéologiques de l'interface. Dans un premier temps nous avons utilisé la géométrie modèle qu'est la goutte pendante pour étudier indépendamment les différents phénomènes impliqués dans l'assemblage des multicouches et dans leur déformation. Nous avons revisité différents modèles classique pour décrire l'adsorption de nos polymères à l'interface, puis nous avons mesuré les modules interfaciaux de différents systèmes de polymères. Pour cela, à l'aide de mesures complémentaires, nous avons établi un cadre pour les mesures de modules élastiques en goutte pendante. Dans un second temps, nous avons utilisé la microfluidique pour fabriquer différents types de micro-capsules et pour mesurer leurs propriétés mécaniques. Celles-ci résultent des différents phénomènes étudiés dans la première partie de cette thèse. Nous avons établi un modèle et effectué des simulations numériques qui nous permettent d'extraire les principales propriétés interfaciales de nos capsules à partir de la mesure de leur déformation dans les canaux microfluidiques. / In order to improve control over the delivery of chemicals, industries seek a way to encapsulate them. A promising method to produce artificial micro-capsules consists in assembling several layers of polymer at the interface of an oil droplet or an air bubble. This thesis focuses on these multilayer assemblies of polymers at liquid interfaces. Through experimental observations on model interfaces and modeling, we studied the effect of the molecular interactions of polymer chains at an interface between two immiscible fluids on the rheological behaviour of this interface. In a first part, we used the model macroscopic geometry of the pendant drop to study independently the different phenomena taking place during the assembly and the deformation of the multilayers. We revisited classical models to describe the adsorption dynamics of our polymers, and we measured the interfacial dilational modulus of various systems. To this aim, by performing independent measurements, we delimited the range of validity of the pendant-drop apparatus. In the second part, we used microfluidics to create micro-capsules of different kinds and to probe their mechanical properties resulting from all the phenomena studied in the first part. We developed a model and we performed numerical simulations to extract the main interfacial properties of our capsules from the measurement of their deformation in the channels.

Orientadores: Miriam Dupas Hubinger, Vanessa Martins da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T08:01:27Z (GMT). No. of bitstreams: 1 Carvalho_AnaGabrieladaSilva_M.pdf: 18654651 bytes, checksum: b9cbc1f805b1d0974af4067819e06088 (MD5) Previous issue date: 2013 / Resumo: O óleo de café verde merece destaque na área cosmética por sua capacidade de bloquear a radiação solar UVB (290-320 nm) e por suas propriedades emolientes. Nesse contexto, para melhor aproveitar as propriedades desse óleo e aumentar a sua estabilidade oxidativa, pretendeu-se com este trabalho produzir micropartículas de óleo de café verde, pelo processo físico de spray drying. Como agentes encapsulantes foram utilizados lecitina, um fosfolipídeo de caráter aniônico quando em pH 3,0, quitosana, um polissacarídeo de caráter catiônico também em pH 3,0 e solúvel somente em sistemas ácidos diluídos, além de sólidos de xarope de milho ou amidos modificados derivados do milho, HiCap 100 e Snow-Flake. O preparo das emulsões foi feito através da técnica de estabilização por atração eletrostática de cargas opostas entre a lecitina e a quitosana. Com o propósito de se obter emulsões com dupla camada estáveis à separação de fase, foi utilizado um rotor-estator e um homogeneizador a alta pressão. As emulsões foram analisadas quanto à estabilidade, distribuição de tamanho e diâmetro médio das gotas, microscopia ótica, potencial zeta e comportamento reológico. As emulsões preparadas com Snow-Flake e xarope de milho/Snow-Flake (50/50) apresentaram comportamento pseudoplástico, além de apresentarem os maiores diâmetros de gota variando de 3,70 a 5,19 µm. Contudo, as emulsões com xarope de milho, HiCap 100 e xarope de milho/HiCap 100 (50/50) apresentaram comportamento de fluidos Newtonianos e diâmetros menores de gota, entre 1,15 e 1,51 µm. Para o processo de secagem foi utilizado um secador laboratorial do tipo mini spray dryer, com temperatura do ar de secagem de 170 °C. As micropartículas obtidas foram caracterizadas em relação ao conteúdo de umidade, atividade de água, distribuição de tamanho e diâmetro médio de partículas e microestrutura. Além disso, foram também determinados: a eficiência de encapsulação, o fator de proteção solar in vitro das micropartículas e estabilidade oxidativa pelo método Rancimat. As micropartículas apresentaram diâmetro entre 14,51 e 29,19 µm e excelentes valores de eficiência de encapsulação, superiores a 84%. As partículas produzidas com os amidos modificados apresentaram formato esférico sem rachaduras ou poros, já as micropartículas produzidas com somente xarope de milho apresentaram alguns poros e rachaduras, que causaram a menor estabilidade oxidativa dessas micropartículas. As micropartículas produzidas com HiCap 100 e xarope de milho/HiCap 100 (50/50) estabilizadas por lecitina-quitosana apresentaram maior estabilidade oxidativa. O fator de proteção das partículas variou entre 1,37 e 2,45, sendo de 2,12 para o óleo de café verde puro / Abstract: The green coffee oil stands out for its ability to block the UVB radiation (290-320 nm) and its emollient property. In this context, to improve the properties of this oil and increase its stability, the aim of this work was to produce microparticles of green coffee oil by spray drying. Encapsulating agents used were lecithin, a phospholipid with anionic character at pH 3.0, chitosan, a polysaccharide with cationic character also in pH 3.0 and soluble only in diluted acid solutions and corn syrup solids or corn modified starches as HiCap 100 and Snow-Flake. Emulsions preparation involved the technique of stabilization by electrostatic attraction between lecithin and chitosan. A rotor-stator homogenizer and a high pressure homogenizer were used in order to obtain stable emulsions by electrostatic layer-by-layer deposition. The emulsions were analyzed in relation to stability, size distribution and droplet diameter, optical microscopy, zeta potential and rheological behavior. The emulsions prepared with Snow-Flake and corn syrup/Snow-Flake (50/50) showed pseudoplastic behavior, besides having the biggest droplet diameters ranging from 3.70 to 5.19 µm. However emulsions prepared with corn syrup, HiCap 100 and corn syrup/HiCap 100 (50/50) showed Newtonian behavior and smaller droplet diameters ranging from 1.15 to 1.51 µm. For the drying process, a laboratory spray dryer and air temperature of 170 °C were used. Microparticles were characterized with respect to moisture content, water activity, particle size distribution and microstructure. Furthermore, encapsulation efficiency, sun protection factor in vitro and oxidative stability by the Rancimat method were determined. The microparticles had a diameter ranging from 14.51 and 29.19 µm and high values of encapsulation efficiency, above 84%. The particles produced with modified starches showed spherical shape without cracks or pores and those produced with only corn syrup showed some holes and cracks, that caused lower oxidative stability of these microparticles. The microparticles produced with HiCap 100 and corn syrup/HiCap 100 (50/50) stabilized by lecithin-chitosan showed the highest oxidative stability. The sun protection factor of particles ranged from 1.37 and 2.45 and 2.12 for the pure green coffee oil / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

A liberação controlada de fármacos é um tópico importante para várias iniciativas em nanotecnologia devido ao possível impacto para a sociedade, com a criação de sistemas otimizados que garantam a liberação num sítio específico e a uma taxa controlada. Dentre os vários paradigmas de liberação controlada destaca-se o uso de lipossomos, uma vez que muitos fármacos e drogas podem ser transportados. Este trabalho descreve a fabricação de filmes automontados de lipossomos que incorporam o fármaco ibuprofeno. Os lipossomos foram preparados de dipalmitoil fosfatidil colina (DPPC), dipalmitoil fosfatidil glicerol (DPPG) e palmitoil-oleoil fosfatidil glicerol (POPG), cujas camadas foram alternadas por interações eletrostáticas com camadas do dendrímero PAMAM geração 4. Medidas de espalhamento dinâmico de luz indicaram que a incorporação do ibuprofeno tornou os lipossomos de DPPC e DPPG mais estáveis, com uma diminuição no diâmetro médio de 140 para 74 nm e 132 para 63nm, respectivamente. Ao contrário, os lipossomos de POPG ficaram menos estáveis, com aumento do diâmetro de 110 para 160 nm. A influência na estabilidade foi confirmada em medidas de microscopia de força atômica nos filmes automontados, que mostraram grande tendência à ruptura nos lipossomos de POPG com a incorporação de ibuprofeno. O crescimento dos filmes automontados foi investigado com espectroscopia de fluorescência e uma balança de cristal de quartzo. A intensidade da fluorescência devida ao ibuprofeno aumentou exponencialmente com o número de camadas depositadas, mas não por causa de uma crescente adsorção de ibuprofeno. Ao contrário, a quantidade de material adsorvido nas primeiras camadas aumentou inicialmente, mas depois diminuiu drasticamente após a 6ª. bicamada, e o filme praticamente pára de crescer a partir da 10ª. bicamada. Portanto, a grande fluorescência para filmes espessos deve ser associada a um ambiente favorável, que aumenta a emissão quântica do ibuprofeno. A liberação do ibuprofeno, estudada com medidas de fluorescência, é mais lenta quando incorporado em lipossomos. Em experimentos com uma membrana de diálise, notamos que o tempo de decaimento do ibuprofeno puro é 5,2 h, enquanto este tempo aumentou para 9,2 e 8 h para ibuprofeno encapsulado em lipossomos de DPPG e POPG, respectivamente. O ibuprofeno também foi liberado de filmes automontados contendo lipossomos de DPPG e POPG, o que é promissor para o uso em bandagens (patches). / Controlled drug delivery is a key issue in a number of nanotechnology endeavors owing to the large impact on society that may achieved if improved systems are created which allows for delivery at a specific target and with a controlled rate. Among the various paradigms employed in drug delivery, the use of liposomes is prominent because a variety of drug molecules can be carried. This work describes the fabrication of layer-by-layer (LbL) films made with liposomes incorporating ibuprofen. The liposomes were made with dipalmitoyl phosphatidyl choline (DPPC), dipalmitoyl phosphatidyl glycerol (DPPG) and palmitoyl-oleoyl-phosphatidyl glycerol (POPG), whose layers were alternated with layers of the dendrimer PAMAM generation 4 via electrostatic interactions. According to dynamic light scattering measurements, the incorporation of ibuprofen caused DPPC and DPPG liposomes to become more stable, with a decrease in diameter from 140 to 74 nm and from 132 to 63 nm, respectively. In contrast, liposomes from POPG became less stable, with an increase in size from 110 to 160 nm. These results were confirmed with atomic force microscopy images of LbL films, which showed a large tendency to rupture for POPG liposomes. The film growth was monitored with fluorescence spectroscopy and a quartz crystal microbalance (QCM). The fluorescence intensity arising from ibuprofen increased exponentially with the number of layers, but this was not caused by an increased adsorption of ibuprofen. Instead, the QCM measurements showed that the amount of material adsorbed increases initially with the number of PAMAM/liposome(ibuprofen) layers, but after the 6th bilayer it decreases sharply and film growth practically stops after the 10th layer. Therefore, the inevitable conclusion is that the increased fluorescence is due to a favorable environment for the ibuprofen, whose quantum emission efficiency increases with the number of layers deposited. Also using fluorescence measurements, we noted that release of ibuprofen was delayed when incorporated in liposomes. For instance, in a membrane dialysis experiment, the characteristic decay time was 3.5 h for ibuprofen in solution, whereas this time increased to 9.2 and 8 h for ibuprofen encapsulated into DPPG and POPG liposomes, respectively. Ibuprofen could also be released from the LbL films made with DPPG and POPG liposomes, which is promising for further use in patches.

Neste trabalho foram estudadas as propriedades de adsorção de poli(omethoxianilina) (POMA) em filmes automontados, nos quais camadas de POMA foram alternadas com camadas de ácido polivinil sulfônico (PVS). Devido à baixa solubilidade da POMA, o método de preparação das soluções aquosas de POMA interfere nas características da adsorção. Para POMA com controle de massa molar, que contém fração de alta massa, a cinética de adsorção de uma camada de POMA em filmes de POMAlPVS obedece a um processo de dois estágios. O primeiro é um processo de primeira ordem enquanto o segundo é descrito pela função de Johnson-Mehl-Avrami com n=1, característico de crescimento de bastões. Este tipo de crescimento foi confirmado através de análises do tamanho dos agregados em medidas de microscopia de força atômica (AFM). As propriedades morfológicas desses filmes POMAlPVS foram analisadas usando leis de escala, onde a dimensão fractal foi 2.2, indicando adsorção self-affine. Para POMA polidispersa sem controle da massa molar, a quantidade de material adsorvido aumenta não monotonicamente com o tempo devido à competição entre os mecanismos de adsorção e dessorção. Tal competição foi também manifestada nas propriedades morfológicas, com o tamanho do grão nos filmes de POMAlPVS aumentando não monotonicamente com o tempo. A importância das ligações de hidrogênio no mecanismo de adsorção para POMA foi demonstrada em alguns experimentos. Por exemplo, foi mostrado que a adsorção é eficiente para soluções de POMA com pH 5 em que a POMA não está dopada e, portanto a atração iônica não pode ser responsável pela adsorção. Além disso, observou-se adsorção não autolimitada da POMA, a qual depende das interrupções no processo de adsorção. Foi notada, através de medidas de calorimetria de varredura diferencial (DSC), a presença de água no pó de POMA e em filmes automontados POMAlPVS sobre esferas de sílica. A energia de adsorção variou de 6 a 15 kcallmol, que pode ser atribuída a ligações de hidrogênio. Devido a ligações de H a quantidade de material adsorvido aumenta com o número de bicamadas, e isto é refletido na isoterma de adsorção da POMA. As isotermas foram analisadas com o modelo de Filippova que descreve a cinética de adsorção de polieletrólitos em uma superfícies plana, e permite obter energias de ativação para as interações entre polieletrólitos/polieletrólitos, polieletrólitoslinterface e polieletrólitos/solvente. A energia de interação entre as moléculas adsorvidas no substrato (vidro ou filme automontado com bicamadas de POMAlPVS) aumenta com o número de bicamadas de 0.9 kcallmol para substrato de vidro a 5.39 kcal/mol para uma camada de POMA adsorvida em um filme com 10 bicamadas de POMAlPVS / This thesis addresses the adsorption properties of poly(o-methoxyaniline) (POMA) in layer-by-Iayer (LBL) films, for which POMA layers were alternated with layers of the polyanionic poly(vinylsulfonicacid) (PVS). Due to the reduced solubility of POMA, the method of preparation of POMA aqueous solution sinterfered in the adsorption characteristics. For POMA with controlled mass, which contained high molecular weight fractions, the kinetics of adsorption of a POMA layer on already deposited POMA/PVS films obeyed a two-step process. The first process is a firs torder kinetics process while the second one is described by the Johnson-Mehl-Avrami function with n = 1, characteristic of preferential growth of cylinders. This growth was confirmed in the analysis of aggregate size in atomic force microscopy (AFM) measurements. The morphological properties of these POMA/PVS films were analyzed using scaling laws, where the fractal dimension was approximately 2.2, denoting self-affine adsorption. For polydisperse POMA with no control of \"molecular weight\", the amount of material adsorbed increased non-monotonically with time due to a competition between adsorption and desorption mechanisms. Such competition was also manifested in themorphological properties, with the grain size in POMA/PVS films increasing non-monotonically with time. The importance of H-bonding in the adsorption mechanisms for POMA was demonstrated in several instances. For example, it is shown that POMA adsorption is efficient for solutions with pH 5 where POMA is not doped and therefore ionic attraction cannot be held responsible for adsorption. Moreover, non-self-limited adsorption of POMA was demonstrated, which depended on the interruptions in the adsorption process. H-bonding probably occurs in entrained water, which was shown to be present in POMA powder and in POMA/PVS films deposited on silica particles, using differential scanning calorimetry (DSC). Activation energies of 6-15 kcal/mol were estimated, which can be attributed to H-bonding. Because of H-bonding interactions the amount of material adsorbed increases with the number of bilayers, and this is reflected in the adsorption isotherms for POMA. The latter were analyzed with Fillippova\'s model in which the adsorption kinetics of polyelectrolytes on a planar surface is described. It allows estimation of activation energies characterizing interactions between polyelectrolyte/polyelectrolyte, polyelectrolyte/interface and polyelectrolyte/solvent. The energy of interaction between the molecules to be adsorbed and the substrate (bare or coated with POMA/PVS layers) increases with the number of bilayers, from 0.9 kcal/mol for the bare substrate to 5.39 kcal/mol for a POMA layer adsorbed on a 10-bilayer POMA/PVS film

Die vorliegende Dissertation untersuchte die Kombination von DNA-Nanostrukturen, so- genannte DNA-Origami-Strukturen, mit Layer-by-Layer (LbL) Mikrotransportern zum Auf- bau eines verbesserten Medikamententrägersystems. Dies sollte die jeweiligen Vorteile der eigenständigen Systeme kombinieren um individuelle Nachteile, wie etwa die li- mitierte Stabilität der DNA-Origami-Strukturen unter physiologischen Bedingungen als auch die schrittweise Freisetzung transportierter Medikamente aus der durchlässigen Polymerschicht der LbL-Mikrotransporter, zu umgehen. Die Untersuchungen bestrebten somit die Oberflächenfunktionalisierung der LbL-Mikrotransporter, um den gerichteten Transport in spezifische Zielzellen zu ermöglichen. Im Weiteren sollte die simultane Aus- schüttung des Medikamentes durch geschützte, in die Polymerschicht integrierte, schalt- bare DNA-Origami-Strukturen erreicht werden. Dahingehend wurde zunächst die Verkapselung des Rinderserumproteins und Strept- avidins mittels eines angehangenen DNA-Stranges gezeigt. Dieser hybridisierte an die Komplementärsequenz im Inneren von DNA-Origami-Röhren und geschlossenen Käfi- gen mit rechteckigem Grundriss. Um die für den späteren Medikamententransport not- wendige Ablösung des Proteins aus der Struktur zu untersuchen, wurde das gebundene Protein durch externe Zugabe eines invasiven Stranges und einem einzelsträngigen Über- hang am Bindungsstrang nach der Technik des toehold-mediated strand displacements, dem Überhang-bedingten Strangaustausch, vom Bindungsstrang abgelöst. Die umfassende Un- tersuchung zeigte, dass die Wände geschlossener DNA-Origami-Käfige sowohl für einzel- strängige DNA als auch für Proteine teilweise permeabel waren. Im Gegensatz zu unge- schützten Strukturen, zeigten die in die LbL-Polymerschicht integrierten DNA-Origami- Strukturen in anschließenden Stabilitätsstudien eine deutliche Resistenz gegenüber phys- iologisch degradierenden Faktoren. Zum Ziel des Medikamententransports wurden die hybriden Transporter daraufhin umfassend im Zusammenspiel mit kultivierten Zellen untersucht, wobei sich eine gute Interaktionsrate bei vernachlässigbarer Toxizität des Sys- tems zeigte. Die weitere Verbesserung der biologischen Kompatibilität und Selektivität der Transporter wurde im letzten Schritt durch Oberflächenfunktionalisierung mittels einer Lipiddoppelschicht erreicht. Die zusätzliche Anbindung spezifischer Antikörper an diese Doppelschicht führte anschließend zu einer Verbesserung der Aufnahmerate bei Expres- sion des entsprechenden Rezeptors an der Zelloberfläche. Diese Arbeit zeigte somit die grundlegende Charakterisierung des hybriden Transport- systems aus DNA-Origami-Strukturen und LbL-Mikrotransportern, sowie dessen weitere Funktionalisierung und bildet daher die Grundlage für weiterführende Studien.

Clean water is necessary for human survival and there is a need for development of cheap and easy water purification techniques to use in emergency situations when there is no access to safe drinking water. Bacteria contaminated water can cause lethal diarrheal diseases and is globally the second most common cause of death among children less than five years of age. Bacteria adsorbing filter paper made from cellulose could be an environmentally and economically sustainable alternative for disposable water purification filters. This thesis investigates the possibility to use polyelectrolyte multilayer modified cellulose pulp fibers and filter papers to adsorb and remove bacteria from water. The bacterial removal efficiency of the modified materials has been tested both in suspension and through filtration. The surface modification provides the cellulose fibers with a positively charged surface that can attract and bind the negatively charged bacteria. The bacterial adsorption through electrostatic interactions makes it possible to remove bacteria, even when the pore size of the cellulose filters is larger than bacteria. Bacterial reduction tests shows that it is possible to remove over 99.9 % of the bacteria when filtering water through the modified materials. An increased amount of adsorbed cationic polyelectrolyte, polyvinylamine, resulted in an increased bacterial removal capacity. It has also been shown that the bacterial removal efficiency increases with an increased the amount of bacteria adsorbing materials in the filter. The modified materials have been compared with a commercial product and the filtration efficiency has shown to be greater for the polyelectrolyte-modified materials, under the test conditions used in this thesis. Tests with natural water samples shows that it is important to use a filtration mode to remove particles from the water in combination with the bacterial adsorption, as the particles interfere with the bacterial adsorption. / Säkert dricksvatten är nödvändigt för överlevnad och det finns ett stort behov av att utveckla nya billiga och enkla tekniker för att rena vatten i nödsituationer där det inte finns tillgång till detta. Dricksvatten förorenat av bakterier kan orsaka dödliga diarrésjukdomar och är globalt den näst vanligaste dödsorsaken bland barn under fem år. Denna avhandling undersöker möjligheten att använda cellulosafibrer och filterpapper, ytmodifierade med multilager av katjoniska polyelektrolyter, för att adsorbera och avlägsna bakterier från vatten. Bakterieradsorberande filterpapper tillverkat av cellulosa kan vara ett miljövänligt och ekonomiskt hållbart alternativ för vattenreningsfilter för engångsbruk. De modifierade materialens förmåga att adsorbera bakterier har testats både i suspension och via filtrering. Ytmodifieringen ger cellulosafibrerna en positivt laddad yta som kan attrahera och binda de negativt laddade bakterierna. Avlägsnandet av bakterier genom elektrostatisk interaktion gör det möjligt att ta bort bakterier, även när filtret har en porstorleken som är större än bakterierna. Bakteriereduktionstesterna visar att det är möjligt att avlägsna mer än 99,9 % av bakterierna vid filtrering genom de modifierade materialen. En ökad mängd adsorberad katjonisk polyelektrolyt, polyvinylamin, resulterade i en ökad bakterieavlägsningskapacitet. Det har också visat sig att effektivitet ökar väsentligt med ökad mängd bakterieadsorberande material i vattenfiltren. De ytmodifierade materialen har jämförts med en kommersiell produkt för vattenrening med goda resultat. Filtreringstesterna utförda i den här avhandlingen visar att de modifierade materialen tar bort mer bakterier än vad det kommersiella filtret inaktiverar. Tester med naturliga vattenprov visar att det är viktigt att använda filtrering för att avlägsna partiklar från vattnet för att uppnå en önskad bakterieadsorption, eftersom partiklarna påverkar bakterieadsorptionen och minskar effektiviteten hos de bakterieadsorberande materialen / <p>QC 20170328</p>

Integration of living cells with novel microdevices requires the development of innovative technologies for manipulating cells. Chemical surface patterning has been proven as an effective method to control the attachment and growth of diverse cell populations. Patterning polyelectrolyte multilayers through the combination of layer-by-layer self-assembly technique and photolithography offers a simple, versatile and silicon compatible approach that overcomes chemical surface patterning limitations, such as short-term stability and low protein adsorption resistance. In this study, direct photolithographic patterning of PAA/PAAm and PAA/PAH polyelectrolyte multilayers was developed to pattern mammalian neuronal, skeletal and cardiac muscle cells. For all studied cell types, PAA/PAAm multilayers behaved as a negative surface, completely preventing cell attachment. In contrast, PAA/PAH multilayers have shown a cell-selective behavior, promoting the attachment and growth of neuronal cells (embryonic rat hippocampal and NG108-15 cells) to a greater extent, while providing a little attachment for neonatal rat cardiac and skeletal muscle cells (C2C12 cell line). PAA/PAAm multilayer cellular patterns have also shown a remarkable protein adsorption resistance. Protein adsorption protocols commonly used for surface treatment in cell culture did not compromise the cell attachment inhibiting feature of the PAA/PAAm multilayer patterns. The combination of polyelectrolyte multilayer patterns with different adsorbed proteins could expand the applicability of this technology to cell types that require specific proteins either on the surface or in the medium for attachment or differentiation, and could not be patterned using the traditional methods.

A wide variety of nanomaterials ranging from polymer assemblies to organic and inorganic nanostructures (particles, wires, rods etc) have been actively pursued in recent years for various applications. The synthesis route of these nanomaterials had been driven through two fundamental approaches - 'Top down' and 'Bottom up'. The key aspect of their application remained in the ability to make the nanomaterials suitable for targeted location by manipulating their structure and functionalizing with active target groups. Functional nanomaterials like polyelectrolyte based multilayered thin films, nanofibres and graphene based composite materials are highlighted in the current research. Multilayer thin films were fabricated by conventional dip coating and newly developed spray coating techniques. Spray coating technique has an advantage of being applied for large scale production as compared to the dip coating technique. Conformal hydrophobic/hydrophilic and superhydrophobic/hydrophilic thermal switchable surfaces were fabricated with multilayer films of poly(allylaminehydrochloride) (PAH) and silica nanoparticles by the dip coating technique, followed by the functionalization with thermosensitive polymer-poly(N-isopropylacrylamide)(PNIPAAM) and perfluorosilane. The thermally switchable superhydrophobic/ hydrophilic polymer patch was integrated in a microfluidic channel to act as a stop valve. At 70 degree centigrade, the valve was superhydrophobic and stopped the water flow (close status) while at room temperature, the patch became hydrophilic, and allowed the flow (open status). Spray-coated multilayered film of poly(allylaminehydrochloride) (PAH) and silica nanoparticles was fabricated on polycarbonate substrate as an anti-reflection (AR) coating. The adhesion between the substrate and the coating was enhanced by treating the polycarbonate surface with aminopropyltrimethoxylsilane (APTS) and sol-gel. The coating was finally made abrasion-resistant with a further sol-gel treatment on top of AR coating, which formed a hard thin scratch-resistant film on the coating. The resultant AR coating could reduce the reflection from 5 to 0.3% on plastic. Besides multilayered films, the fabrication of polyelectrolyte based electrospun nanofibers was also explored. Ultrathin nanofibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylaminehydrochloride) (PAH) were fabricated using the electrospinning technique and methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. The fiber was also loaded with a real life anti-depressant drug (2,3-tertbutyl-4-methoxyphenol) and fiber surface was made superhydrophobic. The drug loaded superhydrophobic nanofiber mat was immersed under water, phosphate buffer saline and surfactant solutions in three separated experiments. The rate of release of durg was monitored from the fiber surface as a result of wetting with different solutions. Time dependent wetting of the superhydrophobic surface and consequently the release of drug was studied with different concentrations of surfactant solutions. The results provided important information about the underwater superhydrophobicity and retention time of drug in the nanofibers. The nanostructured polymers like nanowires, nanoribbons and nanorods had several other applications too, based on their structure. Different self-assembled structures of semiconducting polymers showed improved properties based on their architectures. Poly(3-hexylthiophene) (P3HT) supramolecular structures were fabricated on P3HT-dispersed reduced graphene oxide (RGO) nanosheets. P3HT was used to disperse RGO in hot anisole/N, N-dimethylformamide solvents, and the polymer formed nanowires on RGO surfaces through a RGO induced crystallization process. The Raman spectroscopy confirmed the interaction between P3HT and RGO, which allowed the manipulation of the composite's electrical properties. Such a bottom-up approach provided interesting information about graphene-based composites and inspired to study the interaction between RGO and the molecular semiconductor-tetrasulphonate salt of copper phthalocyanine (TSCuPc) for nanometer-scale electronics. The reduction of graphene oxide in presence of TSCuPc produced a highly stabilized aqueous composite ink with monodispersed graphene sheets. To demonstrate the potential application of the donor (TSCuPc)'acceptor (graphene) composite, the RGO/TSCuPc suspension was successfully incorporated in a thin film device and the optoelectronic property was measured. The conductivity (dark current) of the composite film decreased compared to that of pure graphene due to the donor molecule incorporation, but the photoconductivity and photoresponsivity increased to an appreciable extent. The property of the composite film overall improved with thermal annealing and optimum loading of TSCuPc molecules.