As a continued study on combined use of different antibacterial chemistries, N-chloramine and short chain Quaternary ammonium compound (QAC) were immobilized on modified poly (ethylene terephthalate) (PET) surface in various ratios via “click” chemistry. In this study, contribution of surface bound QAC to the conversion of cyclic and acyclic N-H to N-Cl, fastest recharging chlorination as well as the most effective antibacterial efficacy was investigated. Surface bound positive charge at the density of 8.4x1016charges/cm2 achieved highest equilibrium conversion and facilitated a nine-fold increase in conversion of sterically hindered acyclic N-H to N-Cl from 0.39 to 3.92%. Within the range of 2.8x1016 to 8.4x1016charges/cm2, highest active chlorine loading within first five minutes of chlorination was observed on sample loaded with 4.6x1016charges/cm2.As it comes to PET surface grafted with a cyclic N-chloramine precursor, the presence of 2x1016charges/cm2 enabled a five-fold increase in the conversion of cyclic N-H to N-Cl. The highest biocidal efficacy was observed for sample loaded with cyclic N-chloramine/QAC 17.2:10 which presented total kill of E.coli (5.8 log reduction) in 10 minutes compared to 1.9 log reduction for other ratios (22.8/10, 75.5/10) tested at a similar level of active chlorine(223±6ppm respectively). / October 2016

Contact-active antibacterial surfaces with irreversibly attached antibacterial com-pounds are a sustainable alternative to traditional biocides. No chemicals are released into nature and the antibacterial mechanism reduces the risk of the evolution of re-sistant bacteria. However, the preparation of such surfaces is far from sustainable, as organic solvents and harsh reaction conditions commonly are required. An alter-native option is to use polyelectrolyte multilayers (PEM), based on physical ad-sorption, which can be performed in water-based solutions at room temperature. Although contact-active antibacterial PEMs have been reported previously, this is the first study of renewable cellulosic wood fibres. The build-up of cationic polymer polyvinylamine (PVAm) and anionic polyacrylic acid (PAA) multilayers on model surfaces was studied to optimise adsorption. The amount of adsorbed polyelectrolytes was continuously growing with increasing number of layers, but remained dense and flat as the number of layers increased. The largest adsorption was obtained at a high salt concentration, which shielded the repulsion between the polymers. Model surfaces were also used to evaluate the influence of the polymer and number of layers on the antibacterial properties. Multilayers on model surfaces showed a low bacteriostatic effect, with up to approximately 40 % inhibition for 3 layers of un-modified PVAm/PAA. In contrast, when the same multilayers were applied on cel-lulosic fibres, bacterial-growth inhibition of > 99.9% was obtained. Hydrophobically modified PVAm did not yield better results, despite being superior in solution. An increase in fibre charge by fibre oxidation led to the largest amount of adsorbed pol-ymer and the best antibacterial properties, an effect that lasted for weeks. Electron microscopy study of bacteria on the fibres showed that the bacteria interacted more on a highly charged surface and that the morphology of the bacterial cell could be affected. The effect was suggested to be due to electrostatic interaction with the pos-itively charged modified fibres. The promising results offer the possibilities of a new generation of antibacterial surfaces based on a renewable resource. / Antibakteriella kontaktaktiva ytor som har ett antibakteriellt ämne permanent fäst på ytan är ett miljövänligt och säkrare alternativ till traditionell biocidanvändning. Inget utsläpp av giftiga ämnen sker från ytorna och detta tillsammans med den anti-bakteriella mekanismen minskar risken för att bakterierna utvecklar resistens. Till-verkningsprocessen i sig har dock hittills varit allt annat än miljövänlig, då den ke-miska modifieringen kräver organiska lösningsmedel och har reaktioner som kräver speciella villkor, t ex höga temperaturer. En alternativ ytmodifiering är att använda sig av fysikalisk adsorption av polyelektrolyter i multiskikt, eftersom detta kan göras i vat-tenlösningar och i rumstemperatur. Det här arbetet är det första som beskriver kon-takt-aktiva multilager på förnyelsebara svedbaserade cellulosafiber. Som ett första steg gjordes en adsorptionsstudie på modellytor för att optimera ad-sorptionen av katjonisk polyvinylamin (PVAm) och anjonisk polyakrylsyra (PAA). Med ökande antal lager ökade totala mängden adsorberad polymer samtidigt som multilagerna förblev platta och täta. Den högsta adsorptionen skedde vid en hög salt-halt som minimerade den elektrostatiska repulsionen mellan polymerkedjorna. Modellytor användes även för att studera hur de antibakteriella egenskaperna påver-kades av polymermodifiering och av antal lager. På dessa ytor uppmättes en låg bakte-riostatisk effekt med upp till 40 % inhibering av bakterietillväxten för tre lager av PVAm./PAA När däremot samma multilager fanns på cellulosafiber ökade in-hiberingen till uppemot 99.9 %. Hydrofobmodifiering av PVAm påverkade inte det antibakteriella resultatet när de var i multilager, trots bevisad ökad verkan i lösning. Genom att via oxidering öka fiberladdningen kunde mängden adsorberad polymer yt-terligare öka och resulterade i en förbättrad antibakteriell verkan som höll i sig i flera veckor. Elektronmikroskopi av bakterier på fiber visade en ökad interaktion med hög-laddade ytor och att bakteriernas cellmorfologi kan påverkas av ytorna.Den observerade antibakteriella effekten föreslås vara en följd av elektrostatisk inter-aktion mellan de negativt laddade bakterierna och positivt laddade modifierade fibrena. Resultaten är lovande och banar väg för nya kontakt-aktiva antibakteriella material. / Biointeractive fibres with antibacterial properties

In the pursuit to create more natural, chemical-free antibacterial surfaces, fracture mechanics and the ability of laser-modified surfaces to store an antimicrobial agent have been investigated through the combination of scanning electron microscopy coupled with focused ion beam, infrared spectroscopy, bactericidal tests and a colorimetric method. It was found that the irradiation of a nanosecond pulsed laser on Ti-6Al-4V and 304L stainless steel surfaces creates colored oxide layers with 100-150 nm in thickness and, by using the adequate parameters, it is possible to obtain surfaces with cracks of 1-6 μm deep that not only penetrate the film but also the substrate. Physisorption was used to immobilize nisin, an antimicrobial agent, to the walls of those cracks. Antibacterial tests show that nisin-coated oxide layers exhibit antibacterial activity against Listeria monocytogenes even after immersion in water or the application of mechanical scrubbing, and release kinetics tests demonstrated that nisin desorption is promoted by acidic pH and that nisin is effectively stored into the cracks of stainless steel. The immobilization into the cracks of the titanium oxide layer seem to reveal that there is an excellent anchor between the peptide and the crack walls, but future research is still required.

This thesis is concerned with the chemical modification of polymers in the preparation of a library of materials which exhibit altered surface properties as a result of the surface chemical functionality, with particular emphasis on the development of materials that control biofouling and are antibacterial. Chemical modification of crosslinked polystyrene, in film and microsphere form, was carried out by carbene insertion followed by diazonium coupling. This provided access to a collection of materials with varying surface chemistry, whilst the bulk properties of the polystyrene substrates were maintained. Synthesis of the diaryldiazo and the diazonium salts used to perform the surface modifications is described, as well as the preparation and characterisation of the materials. Analysis of the ability of the materials to adsorb and bind the protein bovine serum albumin (BSA) is presented with data obtained from two methods of observation. Quartz Crystal Microbalance with Dissipation (QCM-D) and a protein assay based on the change in optical density of a BSA/PBS solution are used to demonstrate how the specific surface chemistry of the materials influences the ability to adsorb and bind protein. The behaviour of the materials was time dependent and was rationalised with respect to the surface water contact angle and the calculated parameters polar surface area and % polar surface area of the functional groups added to the surfaces. Finally, penicillin loaded materials were prepared and their antibacterial activity was tested against E. coli and S. aureus, demonstrating that the antibiotic is still active from within the polystyrene scaffold.

Title: Modification of polymeric substrates by means of non-equilibrium plasma Author: Anna Kuzminova Department: Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Ondřej Kylián, Ph.D. Abstract: Processing of polymeric materials by means of non-equilibrium plasma is a topic that reaches increasing attention, which is due to the wide range of possible applications. As an example can be mentioned processing of polymeric foils used for food packaging, where plasma treatment enables to improve their functional properties (e.g. increase their printability or enhance their barrier properties). In the frame of this PhD. thesis two different strategies suitable for the modification of polymeric materials were followed. The first one was based on treatment of polymers by atmospheric plasma. The main attention was devoted to the investigation of influence of atmospheric pressure plasma on surface properties of 8 commonly used polymers, namely on their chemical composition, morphology and wettability. In addition, it was observed that plasma treatment causes also alteration of their mechanical properties, may lead to their substantial etching and in some cases improves their biocompatibility. The second studied strategy was based on coating of polymers with thin functional...

Les polyesters aliphatiques dégradables tels que la poly(e-caprolactone) (PCL), le poly(glycolide) (PGA) ou le poly(lactide) (PLA) présentent de nombreuses applications dans le domaine biomédical. Lors de leur utilisation comme implant, le contrôle des propriétés de surface des polyesters est d'un intérêt considérable. En effet, les interactions avec le milieu vivant ont lieu aux interfaces. Ce travail de thèse vise donc le développement d'une méthode simple et généralisable de couplage de petites molécules, macromolécules et biomolécules sur des surfaces de PLA, en évitant sa dégradation. Cette méthode est basée sur une stratégie en deux étapes, initialement développée en solution sur la PCL et comprenant une activation anionique dans des conditions spécifiques, suivie de la fonctionnalisation par un groupe propargyle afin d'obtenir une surface de PLA « clickable ». Cette méthodologie a ensuite été utilisée pour synthétiser des surfaces de PLA (bio)actives anti-bactériennes et visibles en IRM. Les stratégies ont été initialement développées et optimisées en milieu homogène avec la PCL. Ensuite, les surfaces de PLA ont été modifiées, en milieu hétérogène, par CUAAC de poly(ammonium quaternaire)s fonctionnalisés azoture et d'un complexe de gadolinium fonctionnalisé azoture. / Biodegradable aliphatic polyesters such as poly(e-caprolactone) (PCL), poly(glycolide) (PGA) or poly(lactide) (PLA) are widely used in biomedical applications. When employed as an implantable material, the control of the surface properties of polyesters is of great interest because biochemical reactions occur on the surface or at interfaces. This work proposes a simple and versatile method to immobilize simple molecules, macromolecules, and biomolecules on PLA surfaces while preventing polymer degradation. The method is based on a one-pot, two-step procedure, first developed in solution with PCL and comprises an anionic activation under selected conditions followed by propargylation to form a ¡°clickable¡± PLA surface. This methodology is then employed to generate bioactive surfaces, namely antibacterial PLA surfaces and MRI-visible PLA surfaces. In a first place, chemical strategies are developed and optimized in homogeneous systems using PCL. Subsequently, PLA surfaces are modified, under heterogeneous conditions, by grafting of well-defined ¦Á-azido-functionalized poly(quaternary ammonium)s and an ¦Á-azido-functionalized complex of gadolinium to the propargylated PLA surface using "click" chemistry.