Self-etching dentine bonding agents are a recent addition to the choice of bonding agents which a clinician has available to bond resin restorations to tooth structure. The so-called ‘traditional’, total-etch fourth and fifth generation dentine bonding agents have proven their clinical abilities and the question now remains whether these ‘new’ self-etching dentine bonding agents will clinically perform as well as the ‘proven’ total-etch dentine bonding agents. For the purpose of this dissertation the author completed three research projects which were performed to evaluate the efficacy of a selection of dentine bonding agents and then used the results to compare some properties (shear bond strength, microleakage, and anti-bacterial properties) of total-etch dentine bonding agents with some self-etching dentine bonding agents. All discussions will focus on the three dentine bonding agent properties evaluated by the three research projects performed. The three specific aims of this study were: <ul> <li> To compare the dentine shear bond strength of a selection of self-etching dentine bonding agents with that of a total-etch dentine bonding agent control.</li> <li> To compare dentine and enamel microleakage values of a selection of self-etching bonding agents with that of a total-etch dentine bonding agent control.</li> <li> To evaluate the possible anti-bacterial properties of a selection of dentine bonding agents, with focus placed on the self-etching dentine bonding agent ABFb (Clearfil Protect Bond).</li></ul> The studies performed by the author achieved comparative/similar results to some studies described in the literature but it is clear from the literature that some studies provide conflicting results, especially leakage of enamel margins when using self-etching bonding agents. Taking into consideration the limitations of the three studies performed, it can be concluded that as far as the three evaluated properties of self-etching dentine bonding agents are concerned, they should prove to be acceptable clinical alternatives for use in place of total-etch dentine bonding agents. Copyright / Dissertation (MSc(Odont))--University of Pretoria, 2010. / Odontology / unrestricted

Smart nanomaterials can selectively respond to a stimulus and consequently be activated in specific conditions, as a result of their interaction with electromagnetic radiation, biomolecules, pH change, etc. These nanomaterials can be produced through distinct routes and be used in artificial skin, drug delivery, and other biomedical applications. In this thesis, two smart nanosystems were developed, viz., i) nanocapsules formed by aniline (A) and chitosan (CS) (A-CS) containing silver nanoparticles (AgNPs), with an average size of 78 &plusmn; 19 nm, and ii) polycaprolactone (PCL) nanofibers, fabricated by the electrospinning technique containing AgNP into their bulk, with a diameter of 417 &plusmn; 14 nm. A novel system, based on the incorporation of the as-prepared nanocapsules onto the surface of PCL nanofibers containing AgNps (antibacterial mats), was also developed. The methodology employed avoids the direct contact of silver nanoparticles with the host and optimizes its release to the surrounding environment. The AgNPs release was triggered by exposing the nanocapsules to light at 405 nm. Consequently, the electronic energy vibration resulting from the interaction of the irradiation with the surface plasmon band (SPR) of AgNps, breaking the hydrogen bonds of the nanocapsules and releasing of AgNPs at a time of 150 s. To understand the perturbation of AgNps-Nanocapsules against bacteria, membrane models using Langmuir technique with the phospholipids 1,2-dipalmitoyl-sn-glycero-3-phospho-(1\'-rac-glycerol) (DPPG) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) were employed, which are the main components of cell membrane of Escherichia coli (E. coli). The results suggest that DPPG has more influence on the incorporation of the nanoparticles on the cell membrane. The antibacterial properties of the nanofibers/nanomaterials mats towards E. coli and Staphylococcus aureus (S. aureus) were investigated using the Agar diffusion test for 8 samples. The experiments revealed that the samples based on nanofibers/nanocapsules and irradiation presented a radius of inhibition of 2.58 &plusmn; 0.28 mm for S. aureus and 1.78 &plusmn; 0.49 mm for E. coli. This nanosystem showed to be highly interesting for biomedical applications. / Nanomateriais inteligentes podem responder seletivamente a um estímulo e consequentemente ser ativados em condições específicas, como resultado da sua interação com a radiação eletromagnética, mudança do pH, campo magnético, etc. Esses materiais podem ser produzidos através de distintas rotas e utilizados em aplicações como pele artificial, liberação de fármacos, e outras aplicações biomédicas. Nessa tese, dois nanossistemas inteligentes foram desenvolvidos, a saber: i) nanocápsulas formadas por anilina (A) e quitosana (CS) (A-CS) contendo nanopartículas de prata (AgNps), com um tamanho médio de 78 &plusmn; 19 nm, e ii) nanofibras de policaprolactona (PCL), fabricadas pela técnica de eletrofiação contendo AgNps em seu interior, com diâmetro de 417 &plusmn; 14 nm. Um terceiro sistema foi desenvolvido, baseado na incorporação das nanocápsulas na superfície das nanofibras de PCL contendo AgNps (manta antibacteriana). A metodologia utilizada evita o contato direto das nanopartículas de prata com o hospedeiro e otimiza sua liberação no meio ambiente. As AgNps liberadas foram acionadas pela exposição das nanocápsulas à um fonte de luz em 405 nm. Consequentemente, a vibração da energia eletrônica resultante da interação da irradiação com a banda plasmônica de superfície (SPR) das AgNps, quebra as ligações de hidrogênio da nanocápsula e libera as AgNps no meio em um tempo de 150 s. Para entender a perturbação das AgNps-nanocapsulas contra as bactérias, modelos de membrana foram usados através da técnica de Langmuir com os fosfolipídios 1,2-dipalmitoil-sn-glicero-3- fosfo-(1\'-rac-glicerol) (DPPG) and 1,2-dimiristoil-sn-glicero-3-fosfoetanolamina (DMPE), que são os principais componentes da membrana celular de Escherichia coli (E. coli). Os resultados sugerem que DPPG tem mais influência na incorporação das nanopartículas na membrana celular. As propriedades antibacterianas das mantas de nanofibras/nanomateriais contra E. coli e Staphylococus aureus (S. aureus) foram investigadas usando o teste de difusão Agar em 8 grupos, o qual revelou que o grupo contendo a nanofibra/nanocapsula e irradiação apresentou um raio de inibição de 2.58 &plusmn; 0.28 mm para S. aureus e 1.78 &plusmn; 0.49 mm para E. coli. Este nanossistema mostrou ser altamente interessante para aplicações biomédicas.

Ces travaux ont pour objet l’élaboration de nouvelles structures poreuses non tissées antibactériennes. Différentes stratégies ont été développées : l’une a consisté à élaborer des mats poreux par electrospinning en utilisant un polymère biosourcé et biocompatible et l’autre voie consistait à modifier un support fibreux provenant d’un masque de protection respiratoire commercial. La méthode des assemblages par interactions ioniques en superposant de façon alternative les couches de polymères cationiques et les polymères anioniques à la surface du filtre médian en polypropylène (PP) a permis d’élaborer de nouvelles structures ayant de bonnes propriétés antioxydantes et antibactériennes. Le polymère anionique, dérivé du polymère de cyclodextrine présente l’avantage de pouvoir encapsuler un agent antimicrobien biosourcé, le carvacrol. Une autre approche a consisté à modifier des supports en PP avec de l'acide tannique, un polyphénol d'origine naturelle. Dans cette étude, deux stratégies ont été mises en place afin de fonctionnaliser le PP avec de l’acide tannique (AT). La première est l’extrusion réactive du PP avec l’AT en présence (ou non) de peroxyde de dicumyle (DCP) pour greffer directement l’acide tannique sur le PP. La deuxième stratégie consiste à polymériser l’AT au travers d’une couche poreuse de PP extraite d’un masque de protection commercial, afin de permettre l’immobilisation physique de l’AT à la surface du mat fibreux en PP. Le greffage en surface via un procédé “grafting from” a également été étudié. Ces matériaux ont montré de bonnes propriétés antiradicalaires. / The purpose of this work is to develop new antibacterial non-woven porous structures. Different strategies were developed: one was to develop porous structures by electrospinning using a biosourced and biocompatible polymer, the other was to modify a fibrous support from a commercial respiratory protection mask. Assembling materials using ionic interactions by alternatively superposing cationic polymer layers and anionic polymers on the surface of the polypropylene (PP) median filter allowed to develop new structures with good antioxidant and antibacterial properties. The anionic polymer, derived from the cyclodextrin polymer, has the advantage of being able to encapsulate a bio-based antimicrobial agent, carvacrol. Another approach was to modify PP filters with tannic acid, a naturally occurring polyphenol. In this study, two strategies were implemented to functionalize PP with tannic acid (TA). The first is the reactive extrusion of PP with TA in the presence (or not) of dicumyl peroxide (DCP) to directly graft tannic acid onto PP. The second strategy consists in polymerizing the TA through a porous layer of PP extracted from a commercial mask, in order to allow the physical immobilization of the TA on the surface of the PP fibrous mat. Surface grafting using a "grafting from" process was also studied. These materials have shown good anti-free radical properties.

Smart nanomaterials can selectively respond to a stimulus and consequently be activated in specific conditions, as a result of their interaction with electromagnetic radiation, biomolecules, pH change, etc. These nanomaterials can be produced through distinct routes and be used in artificial skin, drug delivery, and other biomedical applications. In this thesis, two smart nanosystems were developed, viz., i) nanocapsules formed by aniline (A) and chitosan (CS) (A-CS) containing silver nanoparticles (AgNPs), with an average size of 78 &plusmn; 19 nm, and ii) polycaprolactone (PCL) nanofibers, fabricated by the electrospinning technique containing AgNP into their bulk, with a diameter of 417 &plusmn; 14 nm. A novel system, based on the incorporation of the as-prepared nanocapsules onto the surface of PCL nanofibers containing AgNps (antibacterial mats), was also developed. The methodology employed avoids the direct contact of silver nanoparticles with the host and optimizes its release to the surrounding environment. The AgNPs release was triggered by exposing the nanocapsules to light at 405 nm. Consequently, the electronic energy vibration resulting from the interaction of the irradiation with the surface plasmon band (SPR) of AgNps, breaking the hydrogen bonds of the nanocapsules and releasing of AgNPs at a time of 150 s. To understand the perturbation of AgNps-Nanocapsules against bacteria, membrane models using Langmuir technique with the phospholipids 1,2-dipalmitoyl-sn-glycero-3-phospho-(1\'-rac-glycerol) (DPPG) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) were employed, which are the main components of cell membrane of Escherichia coli (E. coli). The results suggest that DPPG has more influence on the incorporation of the nanoparticles on the cell membrane. The antibacterial properties of the nanofibers/nanomaterials mats towards E. coli and Staphylococcus aureus (S. aureus) were investigated using the Agar diffusion test for 8 samples. The experiments revealed that the samples based on nanofibers/nanocapsules and irradiation presented a radius of inhibition of 2.58 &plusmn; 0.28 mm for S. aureus and 1.78 &plusmn; 0.49 mm for E. coli. This nanosystem showed to be highly interesting for biomedical applications. / Nanomateriais inteligentes podem responder seletivamente a um estímulo e consequentemente ser ativados em condições específicas, como resultado da sua interação com a radiação eletromagnética, mudança do pH, campo magnético, etc. Esses materiais podem ser produzidos através de distintas rotas e utilizados em aplicações como pele artificial, liberação de fármacos, e outras aplicações biomédicas. Nessa tese, dois nanossistemas inteligentes foram desenvolvidos, a saber: i) nanocápsulas formadas por anilina (A) e quitosana (CS) (A-CS) contendo nanopartículas de prata (AgNps), com um tamanho médio de 78 &plusmn; 19 nm, e ii) nanofibras de policaprolactona (PCL), fabricadas pela técnica de eletrofiação contendo AgNps em seu interior, com diâmetro de 417 &plusmn; 14 nm. Um terceiro sistema foi desenvolvido, baseado na incorporação das nanocápsulas na superfície das nanofibras de PCL contendo AgNps (manta antibacteriana). A metodologia utilizada evita o contato direto das nanopartículas de prata com o hospedeiro e otimiza sua liberação no meio ambiente. As AgNps liberadas foram acionadas pela exposição das nanocápsulas à um fonte de luz em 405 nm. Consequentemente, a vibração da energia eletrônica resultante da interação da irradiação com a banda plasmônica de superfície (SPR) das AgNps, quebra as ligações de hidrogênio da nanocápsula e libera as AgNps no meio em um tempo de 150 s. Para entender a perturbação das AgNps-nanocapsulas contra as bactérias, modelos de membrana foram usados através da técnica de Langmuir com os fosfolipídios 1,2-dipalmitoil-sn-glicero-3- fosfo-(1\'-rac-glicerol) (DPPG) and 1,2-dimiristoil-sn-glicero-3-fosfoetanolamina (DMPE), que são os principais componentes da membrana celular de Escherichia coli (E. coli). Os resultados sugerem que DPPG tem mais influência na incorporação das nanopartículas na membrana celular. As propriedades antibacterianas das mantas de nanofibras/nanomateriais contra E. coli e Staphylococus aureus (S. aureus) foram investigadas usando o teste de difusão Agar em 8 grupos, o qual revelou que o grupo contendo a nanofibra/nanocapsula e irradiação apresentou um raio de inibição de 2.58 &plusmn; 0.28 mm para S. aureus e 1.78 &plusmn; 0.49 mm para E. coli. Este nanossistema mostrou ser altamente interessante para aplicações biomédicas.

Content: Tannins are high molecular weight polyphenols, naturally synthesized by plants to defend themselves against biotic and abiotic stress factors. Their role as antioxidant, antibiotic and antibacterial agent has been known for many years among agriculture, food, pharma and cosmetics industry. If tannins would perform an antibacterial activity in a vegetable tanned leather, the leather itself could be certified as an antibacterial material. This effect could be very interesting for all the applications in which the leather, being in contact with sweat and bacteria, becomes a solution to reduce more or less severe hyperhidrosis and bromhidrosis. The goal of the study was the assessment of the antibacterial activity of vegetable tanned leathers with natural tannins to produce articles in direct contact with human skin and, therefore, their effect on sweat, bacterial growth and metabolite production. Firstly, the antibacterial activity has been evaluated and compared between leathers tanned with Chestnut, Quebracho and Tara extracts, chrome tanned leathers and synthetic materials. The trial was performed in vitro by inoculating gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacterial strains. A later step defined the most suitable blend of tannins to obtain, after tanning and/or retanning, an antibacterial natural leather. Furthermore, the vegetable tanned leathers, made with this tannins blend, have been the target of an in vivo trial during which 15 panelists have worn two differently made shoes. The lining and insole inside the right shoe have been made with vegetable tanned leathers with tannins, while the ones inside the left shoe contained only synthetic material. The shoes have been worn for 28 consecutive days, followed by a molecular and bioinformatic analysis of microbiota samples taken from the inner surface of the shoes by using a sterile swab. Lastly, a biochemical analysis of volatile short chain fatty acids has been carried out to investigate the byproducts of the bacteria responsible for the unpleasant odor of shoes. Take-Away: 1. Vegetable tanned leather is a wonderful antibacterial material thanks to the presence of natural tannins, such as chestnut, quebracho and tara. This property is appreciated in the production of insole leather, lining, leather goods and automotive interiors. 2. The problem of bromhidrosis (bad feet odor) can be avoided by using vegetable tanned leather. 3. In particular, vegetable leathers tanned with tannins used to make inside part of the shoes permit to avoid the formation of cheesy and acidic odours thanks to their antibacterial properties and their capacity to absorb sweat.

Des nanocomposites polyuréthane-argent (PU-Ag) ont été élaborés à l'aide de deux procédés respectueux de l'environnement et du manipulateur, dans le but de prévenir la colonisation microbienne de ces matériaux. Le premier consiste à incorporer une dispersion aqueuse de nanoparticules d'argent, réalisée ex situ, au cours du procédé de synthèse d'un PU en dispersion aqueuse. Une dispersion de nanoparticules d'argent obtenue par réduction chimique, sous micro-ondes, d'ions d'argent en présence de polyéthylèneglycol a été développée dans l'objectif d'intégrer chimiquement le PEG dans les chaînes de PU. Le second procédé réside dans la réduction photochimique, in situ, d'ions argent dans une matrice PU, en l'absence de tout autre composé chimique.La caractérisation des matériaux obtenus montre une dispersion homogène des nanoparticules d'argent avec des tailles de particules faibles (5 à 50 nm] et une activité biocide des surfaces vis-à-vis de deux souches bactériennes (Pseudomonas aeruginosa et Enterococcus faecalis) sans modification notable des propriétés physicochimiques intrinsèques du PU. / Two environment and human-friendly processes were developed to synthesize polyurethane-silver (PU-Ag) nanocomposites having biocide surfaces able preventing the microbial colonization.The first one, called ex-situ process, consists in incorporating a silver nanoparticles aqueous dispersion during the synthesis process of polyurethane, which is itself carried out in aqueous dispersion. In this case, the chemical reduction of silver ions under microwaves and in the presence of polyethyleneglycol was particularly developed with the aim to chemically incorporate the PEG in the PUchains. For the second process, silver ions dispersed inside a PU matrix were photochemically reduced in situ.The obtained materials exhibit a homogeneous dispersion of silver nanoparticles with small diameter (from 5 to 50 nm) without marked modification of the intrisic physomchemical properties of the PU. Lastly, the antibacterial properties of the surfaces aginst Pseudomonas aeruginosa and Enterococcus faecalis were confirmed.

Les nanocelluloses connaissent un fort développement depuis ces dernières décennies et font l’objet de nombreuses études menées par les industriels et/ou consortiums académiques. Cette étude s’insère dans le cadre d’un projet européen (SUNPAP) visant à l’industrialisation des nanofibrilles de cellulose (NFC). La présente thèse fait l’état de nouveaux procédés de modification chimique de surface des NFC dans une optique de chimie verte. Plusieurs stratégies ont été développées telle que l’emploi de liquides ioniques comme solvant de réaction (décrit comme solvants verts) ou l’utilisation d’une nanoemulsion en phase aqueuse permettant le greffage de surface des NFC. Dans le but d’étudier l’impact de ces modifications chimiques, les substrats ainsi traités ont été par la suite utilisés dans diverses applications. Ainsi, des bionanocomposites ont pu être produits, l’impact sur l’introduction de NFC (modifiées ou non) dans du papier a également été étudié. Une étude sur les propriétés antibactériennes et la biodégradabilité des NFC modifiées est également proposée. Une caractérisation approfondie des NFC vierges et modifiées a été réalisée. Des techniques puissantes et innovantes ont été utilisées pour caractériser ces substrats tels que l’XPS (X-ray Photoelectron Spectroscopy) ou encore la SIMS (Secondary Ion Mass Spectrometry). Toutes ces modifications, applications et caractérisations proposées constituent une avancée et des perspectives prometteuses dans le monde des nanocelluloses. / Nanocelluloses know a strong interest since last decades and they are the subject of many studies led by industrials and / or academic consortia. This study is a part of a European project (SUNPAP) for the industrialization of nanofibrillated cellulose (NFC). This thesis is the state of new methods for the chemical surface modification of NFC with a view of green chemistry. Several strategies have been developed such as the use of ionic liquids as reaction solvent (described as green solvents) or the use of an aqueous medium in order to graft the surface of NFCs. Thus, the treated substrates were then used in various applications. Also, bionanocomposites were produced, the impact of the introduction of NFC (modified or not) in paper sheets has also been studied. A study on the antibacterial properties and biodegradability of modified NFC is also proposed. Several characterizations of neat and modified NFC were performed. Powerful and innovative techniques have been used to characterize these substrates such as XPS (X-ray Photoelectron Spectroscopy) or SIMS (Secondary Ion Mass Spectrometry). All these chemical modifications, applications and characterizations are offered promising prospects in the world of nanocelluloses.

En este trabajo presentamos un plan de negocios para el desarrollo de jabones corporales y faciales a base de insumos naturales con propiedades antibacterianas. Para este proyecto se realizó un análisis de la competencia y el benchmarking de la industria de la cosmética natural con la finalidad de desarrollar productos viables en el largo plazo y un amplio valor diferencial. Asimismo, para validar nuestro modelo de negocio desarrollamos dos hipótesis las cuales fueron validadas mediante experimentos MVP. Mediante estos experimentos pudimos ofrecer finalmente al mercado un producto adaptado a los gustos y preferencias de nuestro público objetivo para el cual tuvimos que realizar la segmentación de nuestro mercado. Luego de ello se realizó el plan de ejecución de nuestro concierge con la finalidad de analizar la demanda y costos de nuestro proyecto para luego realizar nuestra proyección de ventas. Luego de realizar esta proyección también se tuvo que realizar el presupuesto de cada área. Entre estas encontramos a operaciones, recursos humanos, marketing y RSE. Estos presupuestos por lo general iban enfocados hacia las estrategias e inversiones que aplicaremos considerando la imagen que deseamos proyectar en el mercado. / In this paper we present a business plan for the development of body and facial soaps based on natural ingredients with antibacterial properties. For this project, an analysis of the competition and benchmarking of the natural cosmetics industry was carried out in order to develop viable products in the long term and a wide differential value. Likewise, to validate our business model, we developed two hypotheses which were validated through MVP experiments. Through these experiments we were finally able to offer the market a product adapted to the tastes and preferences of our target audience for which we had to carry out the segmentation of our market. After that, the execution plan of our concierge was made in order to analyze the demand and costs of our project and then carry out our sales projection. After carrying out this projection, the budget for each area also had to be made. Among these we find operations, human resources, marketing and CSR. These budgets were generally focused on the strategies and investments that we will apply considering the image we wish to project in the market. / Trabajo de investigación