Dissertations / Theses on the topic 'Antibacterial hydrogels'

Poly(ethylene glycol) (PEG) hydrogels containing tertiary amines were synthesized by thermally-initiated free-radical copolymerization of poly(ethylene glycol) methacrylate (PEGMA), poly(ethylene glycol) dimethacrylate (PEGDMA), and 2-dimethylaminoethyl methacrylate (DMAEMA). The mass fraction of each monomer was varied from 0 to ~1 to determine the composition for optimum mechanical properties and maximum tertiary amine content. Dry films were characterized by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), elemental analysis, dynamical mechanical analysis (DMA), tensile testing, swelling, and differential scanning calorimetry (DSC). The film composition with highest strength, elasticity, swelling, and amine content was found to be 30 wt% PEGDMA due to limited polymerization of DMAEMA with PEGDMA. Films composed of 10 wt% PEGDMA were subsequently quaternized with alkyl bromides of varying chain length (C8, C12, and C16) to impart antibacterial properties to the network. Quaternized films were characterized by elemental analysis, swelling, DSC, and a surface antimicrobial assay. The minimum quaternized DMAEMA concentration for antimicrobial activity was 22 wt% quaternized with C8Br and 30 wt% quaternized with C12Br and C16Br. The most potent alkyl bromide was C8Br followed by C12Br and C16Br. These quaternized PEG-co-poly(DMAEMA) hydrogels show promise as antibacterial materials for biomedical applications.

In order for a drug, or any material used for the purpose of eliciting a change in an organisms’ physical or chemical state, to be effective it must reach the intended target intact and for a sustained rate over time. Drug delivery systems encapsulate a drug to protect it from degradation, prevent side reactions, increase solubility, improve accumulation rates at target sites, and release drugs at a controlled rate. Controlled and sustained release of drugs is achieved by degradation of the carrier triggered by breaking dynamic chemical bonds caused by changes in the chemical environment such as pH or redox conditions. Slow, first order kinetic release of drugs increase therapeutic efficacy while also reducing side effects and other cytotoxicity issues. Up and coming drug delivery systems include hydrogels and nanocarriers such as vesicles. Hydrogel drug delivery systems are unique three-dimensional networks of crosslinked hydrophilic polymers that contain anywhere from 50-90 wt% of water. Drugs can be loaded via encapsulation during the gelation process or may be covalently bound to the polymer backbone before gelation. Amphiphilic molecules or polymers that self-assemble in aqueous solutions to form supramolecular nanostructures, such as vesicles, can encapsulate hydrophilic drugs in the aqueous interior or hydrophobic drugs in the lipophilic bilayer membrane. This study seeks to embed vesicles into a hydrogel to create a hybrid drug delivery system which may be applied as a coating to medical devices to prevent bacterial adhesion and growth, injected directly to a target site, or as an additive for wound dressings. This hybrid system mitigates burst release from the hydrogel, as well as stabilizes the vesicles to afford a longer shelf life. Vesicles are prepared from a novel supramolecular amphiphile composed of thio-alkyl modified��-cyclodextrin as a macrocyclic host, and an adamantyl-dithiopropionic acid modified poly(ethylene glycol) as a linear guest. This host-guest system forms inclusion complexes that self-assemble to bilayered vesicles, which may encapsulate a payload, in aqueous solutions. These vesicles serve as three-dimensional multivalent junctions to form a hydrogel, which may encapsulate a second payload, through a dynamic disulfide exchange crosslinking reaction. This novel drug delivery system will be capable of dual and selective release of two different encapsulated payloads. A pH sensitive acid labile bond embedded in the crosslinker will cleave under acidic conditions to release the payload enclosed in the hydrogel matrix, while a disulfide bond embedded in the supramolecular amphiphile of the free vesicle can be cleaved in the presence of naturally occurring antioxidant glutathione, GSH, to release the second payload. It has been discovered that vesicles efficaciously form, can encapsulate a payload, and are stable for several weeks, up to a month. Vesicle stability is examined in the presence of both intracellular and extracellular concentrations of GSH, and it is found that vesicles are more stable in extracellular concentrations of GSH. Crosslinking of vesicles is attempted at several molecular weights of linear thiol terminated poly(ethylene glycol) crosslinker, concentrations ratios of crosslinker: vesicle, pHs, and temperatures. It can be concluded that the crosslinking density with the linear crosslinker is not high enough to form a hydrogel. Future studies will include 4-arm crosslinkers which are predicted to increase the number of crosslinking points and hence the crosslinking density.

Les hydrogels sont des réseaux 3D retenant de grandes quantités d'eau. Biocompatibles, ils sont utilisés pour la délivrance de médicaments. Dans le but de développer des hydrogels antibactériens, cette thèse présente deux études basées sur l'utilisation d'un tripeptide phosphorylé protégé par un fluorénylméthoxycarbonyle (Fmoc), qui peut s'auto-assembler en hydrogel. Dans la première étude, différentes conditions de préparation (pH, sel, présence de polysaccharide) ont été étudiées pour former un hydrogel autocicatrisant et antibactérien libérant un antibiotique, le florfénicol. Dans la seconde étude, des stratégies de synthèse peptidiques et de phosphoramidites en phase solide ont été combinées pour ajouter le florfénicol au phosphate de tyrosine protégé par le Fmoc via un phosphodiester, clivable par des nucléases produites par des bactéries. Des résultats encourageants ont montré la formation du composé ciblé, ouvrant la voie au design d'un peptide antibactérien auto-défensif
Hydrogels are 3D networks of fibers that retain large amounts of water when swollen. Due to their biocompatibility, they are increasingly used for drug delivery. To develop antibacterial peptide-based hydrogels, this dissertation presents two studies based on the use of a fluorenylmethoxycarbonyl (Fmoc)-protected phosphorylated tripeptide that can self-assemble into a hydrogel. In the first study, different preparation conditions (pH, salt, presence of polysaccharide) were investigated to obtain a self-healing and antibacterial hydrogel capable of releasing an antibiotic, florfenicol. In the second study, a solid-phase peptide and phosphoramidite synthesis strategies were combined to add florfenicol to the Fmoc-protected tyrosine phosphate via a phosphodiester, which can be cleaved by nucleases produced by bacteria. Encouraging results showed the formation of the targeted compound, paving the way for the design of a self-defensive antibacterial peptide

Les « bionanocomposites » à base de soie sont des matériaux qui suscitent un intérêt croissant dans de nombreuses applications, et en particulier dans le domaine biomédical, de par leur capacité à combiner les propriétés de la fibroïne (biodégradabilité, biocompatibilité et propriétés mécaniques intéressantes) et celles des nanoparticules (NP). L’objectif de ce travail est de (i) développer une méthode efficace, et « facile » à mettre en oeuvre, permettant l’élaboration de plusieurs types de bionanocomposites de soie ; (ii) fournir une caractérisation approfondie pour une meilleure compréhension de l’interface soie/NP ; et (iii) présenter des applications pertinentes en relation avec les propriétés spécifiques de ces bionanocomposites. Pour ce faire, les NP, d’or (Au NP), d’argent (Ag NP) et d’oxyde de fer (IONP) ont été utilisées en raison de leurs propriétés bien connues. L’élaboration de bionanocomposites à base de soie, tels que les tissus électrofilées, hydrogels, aérogels, éponges et structures imprimés en 3D est décrite. Une caractérisation approfondie, y compris des mesures in situ (pendant la formation du gel) et des analyses ex situ (une fois le gel formé), des hydrogels de soie montre qu’aucune différence significative n’est observée dans la structure de l’hydrogel, alors que la biocompatibilité des matériaux est préservée. Enfin, une application potentielle pour chaque « bionanocomposite » est présentée. Dans une perspective biomédicale, les hydrogels soie-Ag NP montrent une activité antibactérienne significative. Les hydrogels soie-IONP, implantés dans le cerveau d’un rat et suivis par imagerie de résonance magnétique (IRM), montrent l’induction d’une procédure de régénération du cerveau pendant au moins 3 mois. Dans une perspective liée à la dépollution, les hydrogels soie-Au NP montrent des performances remarquables dans la catalyse de la réaction de réduction du bleu de méthylène par le borohydrure de sodium
Silk-based bionancompoistes have attracted a growing interest in numerous applications, particularly in the biomedical field, owing to their ability to combine the specific properties of silk fibroin (biodegradability, biocompatibility and interesting mechanical properties) and nanoparticles (NPs). This work aims to (i) develop a straightforward, yet efficient, methodology to design various silk bionanocomposite materials; (ii) provide an in-depth characterization regarding the silk/NPs interface and (iii) provide potential applications which are relevant for the use of these bionanocompoistes. To this end, gold (Au NPs), silver (Ag NPs) and iron oxide (IONPs) NPs are used as model nanomaterials due to their well-known properties. The successful design of silk bionancocomposite electrospun mats, hydrogels, cryogels, sponges and 3D printed structures is described. An in-depth characterization, including in situ (during hydrogel formation) and ex situ (once hydrogel is formed), of silk hydrogel bionanocomposites do not reveal any noticeable structural changes of silk hydrogels, while their biocompatibility is not impacted by the incorporation of NPs. Finally, a potential application for each bionanocomposite is presented. In a biomedical perspective, silk-Ag NPs hydrogels bionanocomposites show significant antibacterial activity. Silk-IONPs hydrogel bionanocomposites are implanted into rat’s brain allowing a good monitoring of the implant by magnetic resonance imaging and inducing a brain regeneration process up to 3 months. In depollution perspective, silk-Au NPs hydrogel bionanocomposites show remarkable ability to adsorb and catalyze the reduction of methylene blue dye by sodium borohydride

Titanium and titanium based alloys are widely used in dentistry and orthopedics to replace hard tissue and to mend broken bones. It has become a material of choice due to its low density, high strength, good biocompatibility and its capacity to integrate closely with the bone. Today, modern materials and surgical techniques can enable patients to live longer, and aid in maintaining or regaining mobility for a more fulfilling life. There are, however, instances where implants fail, and one of the primary causes for implant failure is infection. This thesis deals with two possible ways of reducing or eliminating implant associated infections; TiO2 photocatalysis, where a surface can become antibacterial upon irradiation with UV light; and incorporation of silver, where a subsequent release of silver metal ions result in an antibacterial effect. For the TiO2 photocatalysis strategy, a simple and cost effective chemical oxidation technique, using hydrogen peroxide (H2O2) and water, was used to create an active TiO2 surface on titanium substrates. This surface was shown to effectively degrade an organic model substance (rhodamine B) by generating reactive oxygen species (ROS) under UV illumination. However, it was shown that Ti-peroxy radical species remaining in the surface after the H2O2-oxidation process, rather than generation of ROS from a heterogeneous photocatalytic process, was responsible for the effect. This discovery was further exploited in a TiO2/H2O2/UV system, which demonstrated synergy effects in both rhodamine B degradation tests and in antibacterial assays. For the silver ion release strategy, a combinatorial materials science approach was employed. Binary Ag-Ti oxide gradients were co-deposited in a reactive (O2) environment using a custom built physical vapor deposition system, and evaluated for antibacterial properties. The approach enabled synthesis and composition-structure-property evaluation unlikely to have been achieved by traditional means, and the gradient coatings demonstrated antibacterial properties against both S. aureus and S. epidermidis according to silver ion release. The release was shown to depend more on structural features, such as surface area, crystallinity and oxidation state, than on composition. Ag-Ti oxide gradients were also evaluated under UV illumination, as Ag deposits on crystalline TiO2 can enhance photocatalytic properties. In this work, however, the TiO2 was amorphous and UV illumination caused a slight reduction in the antibacterial effect of silver ions. This was attributed to a UV-induced SOS response in the S. epidermidis bacteria. The results of this thesis demonstrate that both TiO2 photocatalysis, or UV induced activation of Ti-peroxy radical species, as well as incorporation of silver are viable antibacterial strategies for titanium biomaterials. However, their clinical applications are still pending risk-benefit analyses of potential adverse host tissue responses.

Le infezioni ortopediche sono una problematica devastante che colpisce il 2% dei pazienti che si sottopongono ad interventi di sostituzione articolari. Il lavoro di ricerca di questo dottorato ha come scopo l'individuazione di sistemi tecnologicamente innovativi per la profilassi e la cura di tali infezioni.

The master's thesis is devoted to developing and preparing a composite hydrogel material that can meet the long-term antibacterial properties through a simple physical cross-linking method. The specific research content is as follows: Using PVA and PHMG as raw materials, without introducing initiator and cross-linking agent, through the freezing-thawing method, an antibacterial hydrogel material was prepared. By controlling the PHMG content, freezing time, the number of freeze-thaw cycles and other conditions, the performance of the hydrogel can be adjusted. The best formulation of the hydrogel is found through characterization methods such as light transmittance, swelling rate, dissolution rate, mechanical properties, biocompatibility, and in vitro antibacterial. Prove that the hydrogel has excellent performance-especially long-term antibacterial ability and safety.
Магістерська робота присвячена розробці та виготовленню композитного гідрогелевого матеріалу, який може мати довготривалі антибактеріальні властивості за допомогою простого фізичного методу поперечного зшивання. Зміст дослідження полягає в наступному. Використовуючи в якості сировини ПВА та ПГМГ, без введення ініціатора та зшиваючого агента методом заморожування-розморожування було виготовлено антибактеріальний гідрогелевий матеріал. Контролюючи вміст ПГМГ, час заморожування, кількість циклів заморожування-відтавання та інші умови, можна регулювати рівень характеристик гідрогелю. Найкращий склад гідрогелю знайдено шляхом дослідження таких характеристик, як світлопропускання, швидкість набухання, швидкість розчинення, механічні властивості, біосумісність та антибактеріальний ефект in vitro. Доведено, що гідрогель має чудові характеристики, особливо довгострокові антибактеріальні властивості та безпечність у застосуванні.
Магистерская работа посвящена разработке и изготовлению композитного гидрогелевого материала, который может обладать длительными антибактериальными свойствами с помощью простого физического метода поперечной сшивки. Содержание исследования состоит в следующем. Используя в качестве сырья ПВА и ПГМГ, без введения инициатора и сшивающего агента методом замораживания-размораживания был изготовлен антибактериальный гидрогелевый материал. Контролируя содержание ПГМГ, время замораживания, количество циклов замораживания-оттаивания и другие условия можно регулировать уровень характеристик гидрогеля. Лучший состав гидрогеля найден путем исследования таких характеристик, как светопропускание, скорость набухания, скорость растворения, механические свойства, биосовместимость и антибактериальный эффект in vitro. Доказано, что гидрогель обладает отличными характеристиками, особенно долгосрочными антибактериальными свойствами и безопасностью в применении.

Yes
Antibacterial hydrogels have been intensively studied due to their wide practical potential in wound healing. However, developing an antibacterial hydrogel that is able to integrate with exceptional mechanical properties, cell affinity, and adhesiveness will remain a major challenge. Herein, a novel hydrogel with antibacterial and superior biocompatibility properties was developed using aluminum ions (Al3+) and alginate− dopamine (Alg-DA) chains to cross-link with the copolymer chains of acrylamide and acrylic acid (PAM) via triple dynamic noncovalent interactions, including coordination, electrostatic interaction, and hydrogen bonding. The cationized nanofibrillated cellulose (CATNFC), which was synthesized by the grafting of long-chain quaternary ammonium salts onto nanofibrillated cellulose (NFC), was utilized innovatively in the preparation of antibacterial hydrogels. Meanwhile, alginate-modified dopamine (Alg-DA) was prepared from dopamine (DA) and alginate. Within the hydrogel, the catechol groups of Alg-DA provided a decent fibroblast cell adhesion to the hydrogel. Additionally, the multitype cross-linking structure within the hydrogel rendered the outstanding mechanical properties, self-healing ability, and recycling in pollution-free ways. The antibacterial test in vitro, cell affinity, and wound healing proved that the as-prepared hydrogel was a potential material with all-around performances in both preventing bacterial infection and promoting tissue regeneration during wound healing processes.
This work was supported by the National Natural Science Foundation of China (32070826 and 51861165203), the Chinese Postdoctoral Science Foundation (2019M650239, 2020T130762), the Sichuan Science and Technology Program (2019YJ0125), the State Key Laboratory of Polymer Materials Engineering (sklpme2019-2-19), the Chongqing Research Program of Basic Research and Frontier Technology (cstc2018jcyjAX0807), Chongqing Medical Joint Research Project of Chongqing Science and Technology Committee & Health Agency (2020GDRC017), and the RCUK China-UK Science Bridges Program through the Medical Research Council, and the Fundamental Research Funds for the Central Universities.
The full-text of this article will be released for public view at the end of the publisher embargo on 12 Feb 2022..

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
O mel é uma mistura complexa constituída de carboidratos, enzimas, aminoácidos, minerais, ácidos orgânicos e flavonóides. Inúmeros trabalhos evidenciam o potencial terapêutico do mel, o qual suas principais propriedades são a atividade antimicrobiana e ação cicatrizante, sendo estas atribuídas a fatores como acidez, osmolaridade, peróxido de hidrogênio (H2O2), catalase e flavonóides. A primeira pesquisa deste trabalho consistiu na determinação da origem floral das amostras de mel, realizada através da análise microscópica do pólen (melissopalinologia). Os espectros demonstraram a variabilidade polínica das amostras escolhidas. Em outro estudo, dois métodos versáteis, envolvendo a espectrofotometria e amperometria, foi aplicado na determinação dos teores de H2O2 em 17 amostras de mel. O H2O2 foi determinado por análise de injeção em fluxo (FIA) e reatores tubulares contendo a enzima peroxidase imobilizada na resina Amberlite IRA-743. A determinação espectrofotométrica baseouse na oxidação do H2O2 pela enzima na presença de fenol e 4-aminoantipirina e o complexo anti-pirilquinonimina gerado, foi proporcional a concentração de H2O2. Na determinação amperométrica, um eletrodo de ouro eletrodepositado com platina, eletrodo de Ag/AgCl(sat) (+ 0,60V) e uma agulha de aço inoxidável foram utilizados como eletrodos de trabalho, referência e auxiliar, respectivamente. O método baseou-se em três medidas no sistema FIA e a diferença entre os sinais revelou a corrente proporcional de H2O2 no mel. Ambos os métodos apresentaram ampla faixa de linearidade (0,5 a 100 µmol L−1) e baixos limites de quantificação e detecção. As concentrações encontradas ficaram entre 4 e 214 µg g-1. A determinação de H2O2 provou a rapidez, exatidão e sensibilidade dos métodos quando associados aos sistemas FIA. Em outro trabalho, um sensor amperométrico para a determinação da catalase (CAT), acoplado ao sistema FIA e reatores tubulares foi desenvolvido. A quantificação fundamentou-se em 2 etapas de injeção: (1) padrão de H2O2 e (2) padrão de H2O2 tratado com a CAT imobilizada na Amberlite IRA-743. A diferença da corrente entre (1) e (2) mostrou o consumo de H2O2 por unidade de enzima imobilizada O mesmo procedimento foi aplicado para as amostras de mel e a linearidade da curva para a determinação da CAT ficou entre 100 e 5000 UI mL-1. Os níveis de CAT variaram de 9 a 99 UI mg-1. Os resultados demonstraram uma boa relação inversa entre os teores de CAT e H2O2. O último estudo avaliou, in vitro, a atividade antibacteriana contra 18 linhagens de bactérias Gram positivas e negativas. O screening antimicrobiano foi determinado aplicando testes de difusão em ágar e diluição em caldo, exibindo as concentrações inibitórias mínimas, conforme recomendações da CLSI. Concentrações de mel variando entre 1 e 30% (v/v) foram estudadas e 5 amostras apresentaram atividade bacteriostática, especialmente contra S. aureus, S. epidermidis e E. coli. Os resultados reforçaram a idéia da utilização do mel como agente antimicrobiano e enfatizaram que o H2O2 não é o único inibidor de crescimento bacteriano, mas sim um dos constituintes com atividade bacteriostática e bactericida.
Honey is a complex mixture of carbohydrates, amino acids, minerals, organic acids and flavonoids. The therapeutic potential of honey is gradually growing and its scientific evidences of effectiveness. Honey has been reported as antimicrobial agent, to promote healing wound and burns and the antibacterial activity is attributed to factors such as acidity, osmolarity, hydrogen peroxide (H2O2), catalase and flavonoids. The first research of this work involved the determination of the floral origin of honey which was achieved by microscopic analysis of the pollen (melissopalynology). The pollen spectrum showed the pollinic variety corresponding to different taxonomic levels. In the other study, two versatile methods involving spectrophotometry and amperometry were applied for the determination of H2O2 in 17 commercial honey samples. H2O2 was determined by flow-injection analysis (FIA) with a tubular reactor containing peroxidase enzyme immobilized on Amberlite IRA-743 resin. The spectrophotometric determination was based on the oxidation of H2O2 by the enzyme in presence of phenol and 4aminoantipirine. The rate of color generation, due to the formation of the antipyrilquinonimine species was proportional to the concentration of H2O2. In the amperometric determination, a gold electrode modified by electrochemical deposition of platinum, an Ag/AgCl(sat) electrode (+ 0.60V) and a stainless steel tube were employed as working, reference and auxiliary electrodes, respectively. This method was based on three measurements in the FIA system and the difference between peaks showed the proportional current of H2O2 in the honey samples. Both methods showed wide linear dynamic range for H2O2 (0.5 to 100 µmol L−1) and low quantification/detection limits. The concentrations found in the analyzed honeys samples were in the range of 4-214 µg g-1 of H2O2. The determination of H2O2 showed the rapidness, accuracy and sensitivity provided by the two methods, while combined with the FIA system. An amperometric sensor for catalase (CAT) detection in association with FIA system and a tubular reactor containing Amberlite IRA-743 was developed. Catalase quantification was based on two injections: (1) H2O2 standard solution and (2) H2O2 standard solution treated with CAT immobilized on Amberlite IRA-743. The difference between the current obtained from (1) and (2) showed the consumption of H2O2 per unit of enzyme immobilized. The same procedure was used to immobilize CAT in honey samples. The linear dynamic range for CAT extends from 100 to 5000 UI mL-1. The levels of CAT vary from 9 to 99 UI mg-1. Taking into account these results, an inverse correlation was obtained between CAT and H2O2 levels. Finally the antibacterial evaluation of honeys samples against 18 bacterial strains including Gram-negative/positive species was studied. The screening of antimicrobial potential was determined using the drop-test agar diffusion and the broth diluiton methods according to the CLSI recommendations. Increasing honey concentrations, varying from 1 to 30% (v/v) were studied and five samples demonstrated bacteriostatic activity against ATCC® S. aureus, S. epidermidis and E. coli bacterial strains. The results of this preliminary study tend to reinforce the use of honey as antimicrobial agent and emphasize that H2O2 is not the only inhibine present in honey, but it is one of the whole group with bacteriostatic and bactericidal activity.

Le contrôle de la formation des biofilms est un enjeu économique majeur pour un grand nombre de secteurs économiques comme la distribution d’eau potable. De nombreuses voies sont explorées pour contrôler leur développement. Ces travaux proposent d’explorer la possibilité de prévenir l’adhésion bactérienne en exploitant les propriétés mécaniques de surface de films minces obtenus par polymérisation plasma basse pression à partir de deux précurseurs : le 2-(diméthylamino)éthyl méthacrylate (DMAEMA) et l’hydroxyéthyl méthacrylate (HEMA). Les résultats des caractérisations des propriétés de surface (AFM, IR, XPS, mouillabilité, nanoindentation par AFM) de ces films minces ont montré qu’il est possible de contrôler les propriétés mécaniques des dépôts polymères plasmas, notamment du HEMA, tout en conservant des propriétés chimiques similaires. Les propriétés d’anti-adhésion bactérienne des films minces HEMA ont été évaluées en utilisant une souche Escherichia coli SCC1 au cours de culture statiques et dynamiques. Ces cultures ont montré que lorsque les propriétés mécaniques de surface sont de l’ordre de 600kPa, elles induisent des propriétés d’anti adhésion et une forte mobilité des bactéries. Sous flux, ces propriétés sont exaltées avec aucune bactérie détéctée au bout de deux heures. Afin de pérenniser cette solution sur plusieurs dizaines d’années, un système multicouche a été développé afin de conduire à un renouvellement périodique des propriétés antibactériennes. De plus, cette stratégie a été développée par polymérisation plasma à pression atmosphérique dans l’optique de son industrialisation
Control of biofilm formation is a major economic challenge for a large number of economic sectors such as the distribution of drinking water. Many strategies have been explored to fight against their development. This work proposes to explore the possibility of preventing bacterial adhesion by playing with mechanical surface properties. To do this, low pressure plasma polymerization of two precursors: 2- (dimethylamino) ethyl methacrylate (DMAEMA) and hydroxyethyl methacrylate (HEMA) has been explored. The results of surface characterizations (AFM, IR, XPS, wettability and AFM nanoindentation) of these thin films showed the possibility to obtain different mechanical properties in wide range (kPa to MPa) with similar chemical surface properties. Bacterial anti-adhesion properties of these films were evaluated using an Escherichia coli SCC1 strain during static and dynamic cultures. These results showed that mechanical surface properties around 600 kPa induced very good bacterial anti-adhesion properties and also revealed mobility of bacteria on the surface. Under flow, these properties were highlighted with almost no bacterial detected after two hours. In order to prolongate the life time of these properties, multilayer system has been proposed and synthesis of these plasma polymer multilayer has been studied at atmospheric pressure for industrial scale up

The antibacterial efficacy of hydrogen peroxide treatments in four fruit juices was determined. Preservative free apple cider, white grape, and purple grape juice were inoculated with ~ 6.4 log CFU/ml of a five strain, acid adapted, nalidixic acid resistant E. coli O157:H7 cocktail. Orange juice was inoculated with a comparable Salmonella spp. cocktail. In the first study, 0.017% and 0.012% H2O2 was added in combination with 0.1% and 0.3% of the dominant organic acid (OA) to 4oC and 25oC juices, with samples taken each day for 21 days. H2O2 was a significant factor in all juices (p < 0.05) except white grape (lack of data), and both 0.017% H2O2 treatments reduced counts in apple cider, orange juice, and white grape to undetectable numbers within 48 hrs as cultured on tryptone soy agar + 0.05% nalidixic acid (TSAN). Treatments in purple grape juice were less effective overall, and more dependent on OA concentration (p < 0.001) than H2O2. There were instances where bacterial survival in apple cider, purple grape, and orange juice continued for 21 days after treatment, and sometimes outlasted the control. These occurrences were dependent on temperature (25oC) and H2O2 (0.012%), but not on OA. However, OA concentration was a significant factor (p < 0.05) overall in apple cider and purple grape juice, but not in orange juice. In the second study, 0.015% and 0.03% H2O2 was added to 10, 25, and 40oC apple cider and orange juice inoculated with 6.4 log CFU/ml E. coli O157:H7 and Salmonella spp. respectively. Only 0.03% H2O2 was effective in reducing counts to undetectable numbers in both juices. However, both temperature and H2O2 were significant factors (p < 0.0001) in bacterial destruction, with 0.03% H2O2 at 40oC giving undetectable numbers at < 3 and < 6 hours in orange juice and apple cider respectively. It has been demonstrated that at ~ > 0.017%, H2O2 can provide a 5 log reduction of these pathogens in fruit juice. Increasing temperature and organic acid concentration can improve its rate of effectiveness in certain juices. However, sensory concerns may negate its use in some products.
Master of Science

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este estudo objetivou avaliar a capacidade de liberação e difusão de íons hidroxila, e a atividade antibacteriana de medicações intracanal, in vitro. No primeiro experimento, canais radiculares de dentes bovinos foram instrumentados. Uma cavidade de 4 mm de comprimento, 2 mm de largura e 0,5 mm de profundidade foi confeccionada no terço médio/apical radicular de cada amostra. A abertura coronária e a superfície externa radicular foram seladas com adesivo e esmalte para unhas, exceto a área da cavidade preparada. Os canais radiculares foram preenchidos com as seguintes medicações: G1: hidróxido de cálcio (Ca(OH)2)/soro; G2: Calen; G3: Calen/PMCC; G4: Calen/Clorexidina (CLX) a 0,4%. Os dentes foram armazenados individualmente em frascos contendo água destilada a 37oC. As medições do pH foram realizadas nos períodos de 1, 3, 7, 14, 21, 30 e 60 dias, com utilização de pHmetro digital. Os resultados mostraram aumento significativo do pH a partir de 3 dias para a pasta Calen/CLX e para as demais pastas a partir de 7 até os 14 dias. Para a pasta Calen ocorreu aumento até os 21 dias. A pasta Calen/PMCC apresentou pH mais elevado até 21 dias, sendo os resultados semelhantes para todos grupos aos 30 dias. Aos 60 dias, os maiores valores de pH foram observados para as pastas Calen/PMCC e Calen. Conclui-se que as diferentes composições de pastas à base de Ca(OH)2 proporcionam difusão de íons hidroxila pela dentina radicular. Em outro experimento, 106 dentes humanos unirradiculados tiveram seus canais radiculares contaminados com Enterococcus faecalis e incubados a 37°C por 21 dias. Em seguida, foram divididos de acordo com a medicação intracanal e o período em: G1: Calen - 7 dias; G2: Calen - 14 dias; G3: Calen/PMCC - 7 dias; G4: Calen/PMCC - 14 dias; G5: Calen/CLX a 0,4% - 7 dias; G6: Calen/CLX a 0,4% - 14 dias; G7: Calen/CLX a 1% - 7 dias; G8: Calen/CLX a 1% - 14 dias....
The aim of this study was to evaluate the release and diffusion of hydroxil ions, and the antibacterial activity of intracanal medication, in vitro. At first study, root canals from bovine teeth were instrumented. A cavity with 4 mm of length, 2 mm of width and 0.5 mm of depth was opened at middle/apical third of each sample. The coronal opening and the external surface of the roots were coated with a nail polish layer and a layer of sticky wax, except on the cavity area. Root canals were filled with the following intracanal medication: G1: calcium hydroxide powder with saline solution (Ca(OH)2); G2: Calen; G3: Calen/PMCC; G4: Calen/Chlorhexidine (CHX) 0.4%. Teeth were stored individually in recipients with distilled water at 37oC. Measurements of pH were made at periods of 1, 3, 5, 7, 14, 21, 30 and 60 days, using a digital pH meter. Results showed a significant increase of pH from 3 days for Calen/PMCC, and from 7 until 14 days for the other medications. For Calen, an increase was observed until 21 days. Calen/PMCC showed the highest pH until 21 days, and all the groups had similar results at 30 days. At 60 days, the highest pH values were observed for Calen/PMCC and Calen. It is possible to conclude that different compositions of calcium hydroxide pastes caused diffusion of hydroxil ions through radicular dentin. In another study, 106 single-rooted human teeth had their root canals contaminated with Enterococcus faecalis and incubated at 37oC for 21 days. Then, these teeth were divided according to intracanal medication and periods: G1: Calen - 7 days; G2: Calen - 14 days; G3: Calen/PMCC - 7 days; G4: Calen/PMCC - 14 days; G5: Calen/CHX 0.4% - 7 days; G6: Calen/CHX 0.4% - 14 days; G7: Calen/CHX 1% - 7 days; G8: Calen/CHX 1% - 14 days. Microbiological samples were collected immediately after intracanal medication removal and after seven days. After serial 10-fold dilutions and culture... (Complete abstract click electronic access below)

The search of novel antibacterial treatment modalities designed to face problems of an- tibiotic Multi Drug Resistance (MDR) associated with the alarmingly low turnover of new clinically approved antibiotic drugs is one of the main challenges in biomedicine. In this frame, the achievement of tailored systems able to release therapeutic agents in a controlled fashion is one of the growing area in the burgeoning field of nanomedicine. Light represents the most elegant and non-invasive trigger to deliver bio-active compounds on demand at the target site with superb control of three main factors, site, timing and dosage, determin- ing for the therapeutic outcome. In addition, light triggering is biofriendly, provides fast reaction rates and offers the great benefit of not affecting physiological parameters such as temperature, pH and ionic strength, fundamental requisite for biomedical applications. Recent breakthroughs of nanotechnology offer the opportunity to characterize, manipulate and organize matter at the nanometer scale, controlling the size and shape of the result- ing nanomaterials and greatly improving the biocompatibility and the cellular uptake effi- ciency. This thesis focuses on the design and fabrication of light-activated nanoconstructs for the controlled delivery of unconventional therapeutics such as reactive oxygen and nitrogen species, and heat which, in contrast to conventional drugs, do not suffer MDR problems and display reduced systemic effects. A range of nanosystems able to generate individually, sequentially or simultaneously the above cytotoxic agents is reported and, in some case, their antibacterial activity is also investigated. This dissertation is divided in two sections: the first one regards nanomaterials, while the second focuses on molecular hybrid systems, all preceded by a brief in-troduction.

Orientador: Juliane Maria Guereiro Tanomaru
Banca: Evandro Watanabe
Banca: Igor Prokopowitsch
Banca: Gisele Faria
Banca: Idomeo Bonetti Filho
Resumo: Este estudo objetivou avaliar a capacidade de liberação e difusão de íons hidroxila, e a atividade antibacteriana de medicações intracanal, in vitro. No primeiro experimento, canais radiculares de dentes bovinos foram instrumentados. Uma cavidade de 4 mm de comprimento, 2 mm de largura e 0,5 mm de profundidade foi confeccionada no terço médio/apical radicular de cada amostra. A abertura coronária e a superfície externa radicular foram seladas com adesivo e esmalte para unhas, exceto a área da cavidade preparada. Os canais radiculares foram preenchidos com as seguintes medicações: G1: hidróxido de cálcio (Ca(OH)2)/soro; G2: Calen; G3: Calen/PMCC; G4: Calen/Clorexidina (CLX) a 0,4%. Os dentes foram armazenados individualmente em frascos contendo água destilada a 37oC. As medições do pH foram realizadas nos períodos de 1, 3, 7, 14, 21, 30 e 60 dias, com utilização de pHmetro digital. Os resultados mostraram aumento significativo do pH a partir de 3 dias para a pasta Calen/CLX e para as demais pastas a partir de 7 até os 14 dias. Para a pasta Calen ocorreu aumento até os 21 dias. A pasta Calen/PMCC apresentou pH mais elevado até 21 dias, sendo os resultados semelhantes para todos grupos aos 30 dias. Aos 60 dias, os maiores valores de pH foram observados para as pastas Calen/PMCC e Calen. Conclui-se que as diferentes composições de pastas à base de Ca(OH)2 proporcionam difusão de íons hidroxila pela dentina radicular. Em outro experimento, 106 dentes humanos unirradiculados tiveram seus canais radiculares contaminados com Enterococcus faecalis e incubados a 37°C por 21 dias. Em seguida, foram divididos de acordo com a medicação intracanal e o período em: G1: Calen - 7 dias; G2: Calen - 14 dias; G3: Calen/PMCC - 7 dias; G4: Calen/PMCC - 14 dias; G5: Calen/CLX a 0,4% - 7 dias; G6: Calen/CLX a 0,4% - 14 dias; G7: Calen/CLX a 1% - 7 dias; G8: Calen/CLX a 1% - 14 dias.... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to evaluate the release and diffusion of hydroxil ions, and the antibacterial activity of intracanal medication, in vitro. At first study, root canals from bovine teeth were instrumented. A cavity with 4 mm of length, 2 mm of width and 0.5 mm of depth was opened at middle/apical third of each sample. The coronal opening and the external surface of the roots were coated with a nail polish layer and a layer of sticky wax, except on the cavity area. Root canals were filled with the following intracanal medication: G1: calcium hydroxide powder with saline solution (Ca(OH)2); G2: Calen; G3: Calen/PMCC; G4: Calen/Chlorhexidine (CHX) 0.4%. Teeth were stored individually in recipients with distilled water at 37oC. Measurements of pH were made at periods of 1, 3, 5, 7, 14, 21, 30 and 60 days, using a digital pH meter. Results showed a significant increase of pH from 3 days for Calen/PMCC, and from 7 until 14 days for the other medications. For Calen, an increase was observed until 21 days. Calen/PMCC showed the highest pH until 21 days, and all the groups had similar results at 30 days. At 60 days, the highest pH values were observed for Calen/PMCC and Calen. It is possible to conclude that different compositions of calcium hydroxide pastes caused diffusion of hydroxil ions through radicular dentin. In another study, 106 single-rooted human teeth had their root canals contaminated with Enterococcus faecalis and incubated at 37oC for 21 days. Then, these teeth were divided according to intracanal medication and periods: G1: Calen - 7 days; G2: Calen - 14 days; G3: Calen/PMCC - 7 days; G4: Calen/PMCC - 14 days; G5: Calen/CHX 0.4% - 7 days; G6: Calen/CHX 0.4% - 14 days; G7: Calen/CHX 1% - 7 days; G8: Calen/CHX 1% - 14 days. Microbiological samples were collected immediately after intracanal medication removal and after seven days. After serial 10-fold dilutions and culture... (Complete abstract click electronic access below)
Doutor

Camila Alencar Moreira. Atividade in vitro de agentes antimicrobianos contra biofilmes de Staphylococcus ssp. de otite canina. 2011. 103 f. Dissertação (Mestrado em Microbiologia Médica) - Universidade Federal do Ceará. Faculdade de Medicina, Fortaleza, 2011.
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Historically, bacteria have been seen as isolated organisms; however, it is now clear that the vast majority of bacteria exist in complex communities known as biofilms. Bacteria in biofilms are adhered to various surfaces, both abiotic and biotic (teeth, bones, mucosa), often forming a highly dynamic ecosystem, which is structured and organized. An example of infection, which can involve the formation of biofilm is otitis - defined as an acute or chronic inflammation of the ear, which may extend from the external ear canal to the inner ear. Described as the most common disease of the external ear canal in dogs, it has a multifactorial etiology, including fungi and bacteria, especially of the genus Staphylococcus. Bacteria of this genus are commensal to skin and mucous membranes, but can act as opportunistic pathogens in favorable conditions and are often associated with a wide variety of infections in humans and animals with many reports of refractoriness to usual treatments. In biofilm, bacteria can be ten to a hundred times more resistant to antibiotics when compared to the same bacteria in planktonic growth. The struggle to fight infections involving bacterial biofilms is a major challenge of microbiology today, which, in turn, leads to the search for new therapeutic options. Thus, this study aimed to evaluate the in vitro inhibitory effect of six substances – three classic antimicrobial agents ciprofloxacin, chloramphenicol, gentamicin; and three non-classic antimicrobial agents thymol, carvacrol, hydrogen peroxide (H2O2) - against staphylococcal strains from canine otitis in planktonic growth and in biofilm. We analyzed 54 clinical strains isolated from purulent secretion of canine otitis, divided into five species: S. intermedius, S. simulans, S. haemolyticus, S.epidermidis and S. lugdunensis. The 16 strains classified as biofilm producers (11 S. intermedius and five S. simulans), according to result obtained by the Congo red agar test and confirmed by scanning electron microscopy (SEM), were used in broth microdilution assay for determination of minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC). With regards to the biofilm-producing strains, the following results were observed: the values for ciprofloxacin were 0,12 ≤MIC≤0,5 mcg/mL (mean 0,28 mcg/mL) and 0,5≤MBIC≤8 mcg/mL (mean 1,79 mcg/mL); for chloramphenicol 2≤MIC≤16 mcg/mL (mean 7,41 mcg/mL) and 8≤MBIC≤32 mcg/mL (mean 20,71 mcg/mL); for gentamicin 0,5≤MIC≤4 mcg/mL (mean 2,09 mcg/mL) and 4≤MBIC≤64 mcg/mL (mean 24,24 mcg/mL); for thymol 32≤MIC≤512 mcg/mL (mean 137,41 mcg/mL) and 256≤MBIC≤2048 mcg/mL (mean 768 mcg/mL); carvacrol 32≤MIC≤512 mcg/mL (mean 128 mcg/mL) and 256≤MBIC≤4096 mcg/mL (mean 993,88 mcg/mL); and for H2O2 for 32≤MIC≤128 mcg/mL (mean 99,76 ppm) and 128≤MBIC≤4096 ppm (mean 1874,82 ppm). The presented data indicates the therapeutic potential of the six antibiotics studied in the treatment of staphylococcal infections associated with biofilm, which warrants further studies to investigate the mechanisms of action of these drugs on biofilms and the design of in vivo experiments to confirm the significance of these findings.
Historicamente, as bactérias foram vistas como organismos que vivem isolados, no entanto, é claro, agora, que a grande maioria de bactérias existe em comunidades complexas, conhecidas como biofilmes. As bactérias em biofilmes se encontram aderidas a superfícies diversas, tanto abióticas como bióticas (dente, osso, mucosa), compondo um ecossistema altamente estruturado, dinâmico e organizado. Um exemplo de infecção que pode envolver a presença formação de biofilme é a otite - definida como inflamação aguda ou crônica da orelha, podendo se estender desde o epitélio do conduto auditivo externo até a orelha interna. Descrita como a doença mais comum do canal auditivo externo em cães, possui uma etiologia multifatorial, que inclui fungos e bactérias, principalmente do gênero Staphylococcus. Bactérias desse gênero são comensais de pele e mucosas, mas podem atuar como patógenos oportunistas em condições propícias e são frequentemente associadas a uma ampla variedade de infecções em seres humanos e animais com vários relatos de refratariedade aos tratamentos usuais. Em um biofilme, as bactérias podem ser dezenas de vezes mais resistentes aos antibióticos, quando comparadas às mesmas bactérias em crescimento planctônico. O combate a infecções envolvendo bactérias em biofilme é um grande desafio da microbiologia mundial, que leva à busca de novas opções terapêuticas. Com efeito, este estudo teve como objetivo avaliar o efeito inibitório in vitro de seis substâncias – três agentes antimicrobianos clássicos, ciprofloxacina, cloranfenicol, gentamicina; e três agentes antimicrobianos não-clássicos timol, carvacrol, peróxido de hidrogênio (H2O2) – contra cepas estafilocócicas de otite canina em crescimento planctônico e em biofilme. Foram avaliadas 54 cepas clínicas isoladas de secreção purulenta de cães com otite, divididas entre cinco espécies: S. intermedius, S. simulans, S. haemolyticus, S. epidermidis e S. lugdunensis. As 16 cepas classificadas como produtoras de biofilme (11 de S. intermedius e cinco de S. simulans), segundo resultado obtido pelo teste do ágar vermelho Congo e confirmação por microscopia eletrônica de varredura (MEV), foram usadas em ensaios de microdiluição em caldo para determinação de concentração inibitória mínima (CIM) e concentração inibitória mínima em biofilme (CIMB). Com relação às cepas produtoras de biofilme, foram observados os seguintes resultados: os valores para ciprofloxacina foram 0,12 ≤CIM≤0,5 mcg/mL (média 0,28 mcg/mL) e 0,5≤CIMB≤8 mcg/mL (média 1,79 mcg/mL); para cloranfenicol 2≤CIM≤16 mcg/mL (média 7,41 mcg/mL) e 8≤CIMB≤32 mcg/mL (média 20,71 mcg/mL); para gentamicina 0,5≤CIM≤4 mcg/mL (média 2,09 mcg/mL) e 4≤CIMB≤64 mcg/mL (média 24,24 mcg/mL); para timol 32≤CIM≤512 mcg/mL (média 137,41 mcg/mL) e 256≤CIMB≤2048 mcg/mL (média 768 mcg/mL); carvacrol 32≤CIM≤512 mcg/mL (média 128 mcg/mL) e 256≤CIMB≤4096 mcg/mL (média 993,88 mcg/mL); e para H2O2 32≤CIM≤128 ppm (média 99,76 ppm) e 128≤CIMB≤4096 ppm (média 1874,82 ppm). Os dados obtidos apontam para o potencial terapêutico dos seis antibióticos estudados no tratamento de infecções estafilocócicas associadas a biofilme, sendo necessários novos estudos para investigar os mecanismos de ação dessas drogas sobre o biofilme, bem como o delineamento de experimentos in vivo para confirmar a significância desses achados.

Periodontium is a complex system of different tissues, such as connective tissue, cartilage and bone, which work together to sustain the tooth. Gingivitis and periodontitis are devastating diseases that could affect the structure and function of the periodontal tissue. When the gingivitis are not treated and controlled with a correct oral hygiene, they could evolve in periodontitis, which could seriously damage the tissue surrounding the tooth and lead tooth loss. The main objective of periodontal tissue engineering is to regenerate the tooth’s supporting tissues. Periodontal tissue regeneration involves formation of new connective tissue (cementum and periodontal ligament) and new alveolar bone. The restoration of tooth by using a titanium dental implant is nowadays a quite common procedure. However, the positive fate of a surgical procedure that involves an insertion of titanium screw depends on the quality and quantity of alveolar bone which is present in the extraction site. The main objective of this doctoral thesis is to develop a set of novel biomaterials, designed to improve periodontal bone regeneration in patients and to control or prevent the bacterial infection in the wound site, via a sustained in situ drug release. Three different materials have been developed and characterized: 1. Three-dimensional porous scaffold coated with a polyelectrolyte complex for periprosthetic infection prevention 2. Bioceramic-reinforced hydrogel for alveolar bone regeneration 3. Antiadhesive guided tissue regeneration membrane The results demonstrated that they could be used in periodontal tissue engineering with predictable and excellent outcomes. With this set of biomaterials it is possible to control or prevent possible bacterial growth, achieve the correct alveolar bone quantity and quality and guide the tissue regeneration

碩士
逢甲大學
材料科學與工程學系
105
Poly(vinyl alcohol) (PVA) which has good physical properties and biocompatibility but no antibacterial activities is being utilized as wound dressings. Chitosan (CS) is a widely used material for its antibacterial activities and good biocompatibility. This study discussed a hydrogel produced by mixing poly(vinyl alcohol) and chitosan and using glutaraldehyde (GA) as a chemical cross-linking agent. Silver particles were then added into the hydrogel by the redox reaction of nitrate (AgNO3) solution. These silver particles which exhibited antibacterial activities were attached to the internal three-dimensional network structure of the hydrogel. Both the physical properties and antibacterial activities of the hydrogel were exanimated. The experimental results showed that the PVA was cross-linked with CS, and the addition of CS had increased the swelling rate of the hydrogel. The specimen 2P3CG exhibited the best swelling rate of 376%. It was known that little CS could enhance the tensile strength of a hydrogel. This was confirmed in the tensile test that the tensile strength of specimen 6P0.5CG was increased by 200% compared to specimen 6P. Scanning electron microscope (SEM) observed the hydrogel consisted of a dense and complete three-dimensional network structure. The antibacterial activities of adding silver particles to the hydrogel were confirmed by antibacterial tests.

碩士
國立臺灣科技大學
化學工程系
107
In this thesis, atmospheric pressure microplasma was employed to prepare self-healing hydrogels with different composition. This thesis is divided into two parts: (part 1): silver loaded self-healing hydrogels, and (part 2): conductive self-healing hydrogels. Both types of the hydrogels were mainly composed by acrylic acid (AA) and ferric chloride (FeCl3). The polymerization of acrylic acid (AA) was proposed to be initiated by the atmospheric pressure microplasma which is postulated to generate free-radicals to initiate radical plasma polymerization. Moreover, the physical cross-linking of hydrogels was facilitated through the carboxylic (COO-) functional groups of polyacrylic acid (pAA) with the added ferric ions (Fe3+) of FeCl3 which resulted in the self-healing hydrogels. Prior to the syntheses of both types of hydrogels, the optimization of concentrations of AA and FeCl3 was facilitated. The pAA-Fe self-healing hydrogels with concentration of AA 3.5 M and FeCl3 17.5 mM exhibited the optimized self-healing efficiency ~68% for 12 h of healing at 37C. In the first part, silver loaded self-healing hydrogels were prepared by mixing AA, FeCl3, silver nitrate (AgNO3), and gelatin (G). In this part, four types of hydrogels were synthesized, (1) pAA-Fe, (2) pAA-Fe/Ag, (3) pAA-Fe-G, and (4) pAA-Fe/Ag-G. SEM images revealed that agglomerated silver chloride nanoparticles (AgCl NPs) were observed in pAA-Fe/Ag, whereas in pAA-Fe/Ag-G, AgCl NPs distributed uniformly due to the stabilization of gelatin. The crystallinity of silver in hydrogels was confirmed by XRD analyses which exhibited five diffraction peaks referring to AgCl NPs (JCPDS 31-1238). Furthermore, the self-healing efficiency of gelatin containing hydrogels, pAA-Fe-G and pAA-Fe/Ag-G were found to be ~59%. The hydrogels contained no gelatin, pAA-Fe and pAA-Fe/Ag, revealed the self-healing efficiency of ~67% for 12 hours of healing at 37C. Moreover, the hydrogels containing silver, pAA-Fe/Ag and pAA-Fe/Ag-G, possessed antibacterial activity against E.coli with inhibition zone of 0.92 and 1.13 cm, respectively. In the second part of this thesis, the conductive self-healing hydrogels composed of AA, FeCl3 and pyrrole monomers were prepared. By atmospheric pressure microplasma treatments, both AA and pyrrole were polymerized to form pAA and polypyrrole (pPy). Herein, the concentration of pyrrole was varied from 3.5 to 7.5 and 10.5 mM namely as pAA-pPy3.5-Fe, pAA-pPy7-Fe and pAA-pPy10.5-Fe, respectively. The decreasing gel fraction was obtained from to 87.5 to 54.5 % with increasing concentration of pyrrole due to pyrrole monomers consumed FeCl3 in the solution forming polypyrrole through oxidative polymerization. The self-healing efficiency of pAA-pPy-Fe hydrogels decreased from 60.5 to 32.1 % with increasing the concentration of pyrrole. This result showed good agreement with gel fraction in which the self-healing efficiency decreased at low gel fraction. Afterward, the effect of undoped and iodine (I2) doped hydrogels were also studied. In this regard, I2 doped hydrogels showed better performance both in antibacterial activity against E.coli bacteria and conductivity by four-point probe method compared to undoped hydrogels. Finally, as representative, pAA-pPy7d-Fe was chosen considering its self-healing efficiency and conductivity for the evaluation of electrical conductivity applications in a simple electrical circuit which was powered by 3 V batteries. Briefly, the initial hydrogel and after-healed hydrogel were able to conduct electricity indicated by lighting-up the LED in the electrical circuit.

碩士
國立臺灣大學
化學工程學研究所
107
In this study, we attempted to produce antimicrobial composite hydrogels consisting of amyloid fibrils and polyphenolic molecules. The amyloid fibrils were made from hen egg-white lysozyme (HEWL), and myricetin and resveratrol were chosen as the polyphenolic molecules. The antibacterial capability, morphology and fluid property of the hydrogels prepared under different conditions were analyzed. The effects of these two polyphenols on amyloid fibrils were also evaluated. Our results showed that, as opposed to the conditions at pH 2 and pH 9, HEWL amyloid fibrils were able to form hydrogels at pH 6 and pH 7.4 after the addition of polyphenols. The antibacterial activity assay was carried out with a high concentration of Gram-negative bacteria E. coli which was mixed with the hydrogel. The mixture was sampled at different times using the spread-plate method to observe for the colony formation. We found that the hydrogels incorporated with myricetin possessed a better antibacterial activity and eliminated bacteria within 8 hr. On the contrary, the amyloid fibril-based hydrogels with resveratrol and amyloid fibrils alone displayed negligible antibacterial activity. The results from the rheological analysis indicated that the viscosity of hydrogels is correlated with the pH value, concentration of polyphenol, and types of polyphenol. Moreover, it was found that the viscosity of the amyloid fibrils increased upon the addition of polyphenols. However, the more the amount of myricetin was added, the less the increase in viscosity. which might be attributed to the fact that the amyloid fibrils may be degraded by myricetin, resulting in structural instability. It should be noted that the similar trend was not seen in the groups with resveratrol. It could be found from the ThT binding analysis that the effects of myricetin and resveratrol on amyloid fibrils were significantly different. The myricetin molecule exhibited a strong competition with ThT for binding positions or ability to degrade amyloid fibrils. Therefore, in the groups of high concentrations of myricetin, the fluorescence intensity was observed to be much lower than that of amyloid fibrils alone. An analogous situation was also encountered in ANS binding analysis- showing that the occupation of exposed hydrophobic area of amyloid fibrillar structure by myricetin likely contributed to the reduction of ANS fluorescence intensity. However, this drastic reduction in ANS fluorescence emission was not perceived in the hydrogels combined with resveratrol. Moreover, hydrogels with the molar ratio of lysozyme fibril to myricetin at 0.1:1 showed better antibacterial ability and mechanical property. Therefore, this hydrogel is a promising antibacterial composite material. The outcome from this study is in support of the potential application of amyloid fibrils as functional biomaterials.

碩士
國立交通大學
材料科學與工程學系奈米科技碩博士班
101
Here, we have developed a novel supramolecular hydrogel–silver nanoparticles (AgNPs) nanocomposite as long term antibacterial wound dressings. The supramolecules are designed that they exhibits many carboxylic acid and thiol groups on the supramolecule nanofibers surface, which can offer as silver metal ion binding sites. The antibacterial nanocomposite was prepared by aqueous reduction method. The supramolecule-Ag ions offer silver metal ion was reduced by NaBH4 agent. These antibacterial nanocomposite does not require any external stabilizing agents with high monodispersity and stability. The nanocomposites were characterized by optical images, UV-vis spectra, Scanning electron microscope (SEM) images and Energy Dispersive Spectrometer (EDS) analysis. They have shown good antibacterial effect against both Gram-positive and Gram-negative bacteria and favorable biocompatibility to Hela cell. Finally, we have been demonstrated a novel supramolecular hydrogel–silver nanoparticles nanocomposites that employs the supramolecule for the development of functional supramolecule that have favorable biostability and capping agent, which offers a novel of supramolecular hydrogels of antibacterial wound dressings applications.

碩士
逢甲大學
材料科學與工程學系
104
This study utilized poly (vinyl alcohol) (PVA) and glutaraldehyde (GA), a crosslinking agent, to produce hydrogel. Silver particles were added into the hydrogel by immersed it in deionized water for swelling, in silver nitrate (AgNO3) solution for ionic exchange, and in sodium borohydride solution (NaBH4) for reduction reaction. This study discussed the properties of poly (vinyl alcohol) hydrogel, and discussed the impact of adding silver particles on poly (vinyl alcohol) hydrogel and the antibacterial properties of silver-added hydrogel. The analyses in first part of this study showed that 2P3G had the best swelling properties, and 6P3G had the highest tensile strength,then silver particles were added into 6P series. The UV-Vis analysis indicated the silver particles were successfully added into the poly (vinyl alcohol) hydrogel, and the SEM showed these silver particles were well-dispersed inside the hydrogel. Silver-added 6P series exhibited antibacterial activities in zone of inhibition testing.

Gels are a special class of materials which are composed of 3D networks of crosslinked polymer chains that encapsulate liquid/air in the matrix. They can be classified into organogels or hydrogels (organic solvent for organogel and water for hydrogel). For hydrogels that contain metallic elements in the form of ions, the term of metallo-supramolecular polymer hydrogel (MSPHG) is often used. The aim of this project is to develop a kind of new MSPHG and investigate its properties and possible applications. The commercial polymeric anhydride poly(methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is converted by reaction with NaOH to give poly(methyl vinyl ether-alt-monosodium maleate) (PVM/Na-MA). By addition of AgNO3-solution, the formation of the silver(I) supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]∙AgNO3 is obtained. Freeze-dried samples of the hydrogel show a mesoporous network of polycarboxylate ligands that are crosslinked by silver(I) cations. The supercritical CO2 dried silver(I) hydrogel was characterized by FT-IR, SEM-EDAX, TEM, TGA and Physical adsorption (BET) measurements. The intact silver(I) hydrogel was characterized by cryo-SEM. In the intact hydrogel, ion-exchange studies are reported and it is shown that Ag+ ions can be exchanged by copper(II) cations without disintegration of the hydrogel. The silver(I) hydrogel shows effective antibacterial activity and potential application as burn wound dressing.

碩士
大同大學
化學工程學系(所)
98
PART 1 Abstract In this study, sodium acrylate were prepared by neutralization of acrylic acid and NaOH, and superabsorbent of poly(sodium acrylate), poly(SA), was prepared by inverse suspension polymerization of sodium acrylate. Different concentrations of silver nanowires were absorbed into superabsorbent materials and the effect of silver nanowires concentration on swelling ratios, swelling rate and antibacterial behaviors were investigated in this study. In addition, comparison of antibacterial experiment of xerogel and wet gel and silver nanoparticles and silver nanowires were carried out and the results also showed that xerogels containing silver nanowires had better antibacterial effect, and silver nanoparticles had better antibacterial effect. The antibacterial behaviors of superabsorbent materials containing silver nanowires could also be proved by observation of surface distribution of silver nanowires via SEM. PART 2 Abstract In this study, aminophthalyl hydrazide (Luminol) was acrylated by acryloyl chloride to prepare acrylamidophthalyl hydrazide (acryl luminol, ALU) monomer, then poly(Acryl Luminol) (PALU) was prepared by free radical polymerization. The chemiluminescence intensity of the luminol monomer and PALU was compared. In addition, a series of copolymeric hydrogels were prepared from 2-hydroxyethyl methacrylate (HEMA) and ALU. Their optical behavior and physical properties were investigated. The results showed that chemiluminescence intensities of PALU and ALU are weaker than the original luminol. In addition, the water content and gel strength of the poly(HEMA-co-ALU) copolymeric hydrogel decrease with the increase of ALU content. The chemiluminescence intensities of the poly(HEMA-co-ALU) copolymeric hydrogels are not obvious.

abstract: Nanostructured zeolites, in particular nanocrystalline zeolites, are of great interest due to their efficient use in conventional catalysis, separations, and emerging applications. Despite the recent advances, fewer than 20 zeolite framework types have been synthesized in the form of nanocrystallites and their scalable synthesis has yet to be developed and understood. Geopolymers, claimed to be “amorphous cousins of zeolites”, are a class of ceramic-like aluminosilicate materials with prominent application in construction due to their unique chemical and mechanical properties. Despite the monolith form, geopolymers are fundamentally nanostructured materials and contain zeolite nanocrystallites. Herein, a new cost-effective and scalable synthesis of various types of nanocrystalline zeolites based on geopolymer chemistry is presented. The study includes the synthesis of highly crystalline discrete nanorods of a CAN zeolite framework structure that had not been achieved hitherto, the exploration of the Na−Al−Si−H2O kinetic phase diagram of hydrogels that gives SOD, CAN and FAU nanocrystalline zeolites, and the discovery of a unique formation mechanism of highly crystalline nanostructured FAU zeolite with intermediate gel products that possess an unprecedented uniform distribution of elements. This study demonstrated the possibility of using high-concentration hydrogels for the synthesis of nanocrystalline zeolites of additional framework structures. Moreover, a comprehensive study on nanostructured FAU zeolites ion-exchanged with Ag+, Zn2+, Cu2+ and Fe2+ for antibacterial applications is presented, which comprises metal ion release kinetics, antibacterial properties, and cytotoxicity. For the first time, superior metal ion release performance was confirmed for the nanostructured zeolites compared to their micron-sized counterparts. The metal ion-exchanged FAU nanostructured zeolites were established as new effective antibacterial materials featuring their unique physiochemical, antibacterial, and cytotoxic properties.
Dissertation/Thesis
Doctoral Dissertation Chemistry 2019

碩士
國立東華大學
光電工程學系
102
Owing to be provided with broader energy gap (3.37 eV), binding energy (60 meV) and greater photocatalytic activity, zinc oxide is widely applied to photoelectric element related works, the study is to fabricate porous zinc oxide photocatalyst bearing carbon fiber composite material under condition of ultrasonic assisted electrochemical in room temperature, and explore its antibacterial ability and conduct photocatalysis hydrogen generation experiment in self-made biofuel. In part 1, the study mainly adopts two different kinds of precursors of zinc acetate and zinc nitrate under ultrasonic assisted to conduct electrochemical deposition on ZnO photocatalyst materials on carbon fiber surface, attempts to find optimal auxiliary parameters in the process. On basis of XRD analysis, it is identified that the fabricated porous ZnO is provided with stronger diffraction peak as experimental parameter is under condition of 28 kHz, with positions of 32.8 and 34.4 degree in 2 angle, and relative crystal planes are 100 and 002 respectively. In cycling voltammetry analysis, it is found that the porous ZnO fabricated with zinc nitrate as precursor is provided with preferred oxidized electric current, where the maximum oxidized electric current can reach 79.5A under xenon lamp irradiation. In part 2, the study adopts the porous ZnO nano photocatalyst materials that fabricated with optimized parameter in part 1, to conduct experiment of photocatalysis escherichia coli antibacterial. As shown in the experiment results, the efficacy of escherichia coli antibacterial is provided with optimal escherichia coli antibacterial curve in first test, but, in second duplicated test, the antibacterial effect reduced to halve, further, in third test, the antibacterial effect is loss, and it is found in electron microscope images that the reason resulted in antibacterial curve uprising lies in ZnO stripping from carbon fiber substrate. In part 3, the study similarly adopts the porous ZnO nano photocatalyst materials that fabricated with optimized parameter in part 1, to conduct experiment of photocatalysis hydrogen generation. Firstly, it is found in the self-made biomass ethanol study, the self-made biomass ethanol fermenting concentration is affected by irradiated light source of various wavelength in the fermenting process, especially under dark condition, the biomass ethanol fabricated after one purification is able to reach concentration of 50 % above, relatively the concentration of biomass ethanol with red light assisted fermenting reaches only 40 %. And then, the fabricated 52 % biomass ethanol is used as sacrifice reagent to conduct photo-decomposition hydrogen generation experiment, and the hydrogen generation efficiency is about 301 mol hr-1.

碩士
國立臺灣科技大學
材料科學與工程系
104
This study is about modification of silicone hydrogel contact lenses. The resultant contact lenses exhibited anti-bacterial activity, anti-adhesion of proteins and high hydrophilicity. Our goal is to create more comfortable and longer-term contact lenses. Antibacterial activity and anti-protein deposition are the most important consideration in the contact lenses. People use contact lenses by touching the contact lenses with their finger. This contact may contaminate contact lenses and lead to inflammation and pain on the cornea. Therefore, anti-bacterial activity is needed to prevent pathogenic problems. Anti-protein deposition is needed to prolong the wearing time of contact lenses. Deposition of proteins and lipids will reduce visual contrast. It was one of the reason contact lenses is uncomfortable to wear. To meet our goal, chitosan (CS) and hyaluronic acid (HA) will be covalently bonded to the surface of the contact lenses (PDMS-CS-HA). According to these ways, we can enable to inhibiting bacteria growth and protein deposition on the contact lenses surface. However, the optical transparency, water content, oxygen permeability, tensile strength and modulus will not significantly change. The overall results demonstrated that new modification of contact lenses has a good potential in the application of ophthalmic lenses