This study aimed at guiding osteoblast cells on biodegradable polymer carriers with well-defined surface microtopography and chemistry, and investigating the effect of cell alignment on osteoblast phenotype expression. A blend of two different polyesters, one being natural in origin (PHBV) and the other synthetic (P(L/DL)LA), was used to form a film with parallel macro- (250 &micro / m wide) or microgrooves (27 &micro / m wide) on its surface, by solvent casting on patterned templates. The micropatterned Si template was produced by photolithography, while the Teflo macropatterned template was lathe cut. Fibrinogen (Fb) was adsorbed or immobilized via epichlorohydrin spacer/crosslinker on the film surfaces to enhance cell attachment by increasing the surface hydrophilicity and by providing RGD amino acid sequence for integrin binding. Surface hydrophilicity was assessed by water contact angle measurements. Adsorption of Fb caused an increase in hydrophilicity, while the opposite was achieved with its covalent immobilization. Fb was homogeneously immobilized throughout the whole micropatterned film surface with amount of 153.1 &plusmn / 42.4 g Fb/cm2, determined with the Bradford assay, while it was adsorbed within the grooves of the micropattern. Surface characteristics of the films were studied with Scanning Electron (SEM) and Light microscopy. Osteoblast cells derived from rat bone marrow were seeded on the polymeric films with different surface topography and chemistry and were grown for one and three weeks. Osteoblast proliferation on the films was determined with Cell Titer 96 TM Non-Radioactive Cell Proliferation (MTS) test. Alkaline Phosphatase (ALP) assay and tetracycline labelling of mineralized matrix were carried out to determine osteoblast phenotype expression on different surfaces. SEM and fluorescence microscopy were used to evaluate the cell alignment. Osteoblasts on the micropatterned films with adsorbed Fb aligned along the groove axis with a mean deviation angle of 13.1o, while on the unpatterned films deviation from horizontal axis was 63.2o and cells were randomly distributed. Cell alignment did not affect cell proliferation. However, the highest ALP specific activity and the most homogeneous mineral distribution were obtained on the Fb adsorbed micropatterned films.

Les nanotechnologies représentent un potentiel de développements et d’applications considérables dans le domaine des matériaux ouvrant la voie à d’innombrables développements pour l’énergie, le transport, la santé, l’industrie, etc. Le biomimétisme a ainsi trouvé un nouveau moteur d'étude et de développement. La feuille de lotus est capable de faire perler l’eau avec une efficacité remarquable transformant n’importe quelle goutte d’eau en une bille répondant aux lois de la physique des solides. Cette propriété extraordinaire est due à l’association d’une composition chimique intrinsèquement hydrophobe avec une texturation hiérarchique de sa surface.Cette thèse s’intéresse à la compréhension des principes physiques qui régissent l'interaction des gouttes d'eau avec les surfaces de films polymères structurées de FEP, PMMA et PET. Deux technologies ont été mises en oeuvre pour la fabrication de surfaces superhydrophobes hiérarchiques : la nanoimpression (NIL) thermique et la gravure plasma. Nous avons mesuré les angles de contact et hystérésis de ces surfaces structurées afin d’identifier leur état de mouillage de Wenzel ou de Cassie-Baxter. Nous avons attaché une importance particulière au développement de solutions de fabrication et de caractérisations sur de grandes surfaces.Les propriétés antigivre ont été caractérisées, ainsi le rôle de la condensation dans la propagation du givre a été corrélé à la structuration de surface. De plus, nous avons mis en évidence le rôle du potentiel électrostatique de surface sur les retards de gel. Enfin, au vue du potentiel applicatif de ces surfaces, nous avons ajouté une dimension dynamique à l’étude en considérant les vitesses d’impact des gouttes. Un modèle de prédiction de la littérature a été comparé avec succès aux résultats expérimentaux. / Nanotechnologies represent a considerable potential of development and application in the field of material science opening the way to innumerable developments for energy, transport, health, industry, and so on. Thus, biomimicry found a new driving force for study and development. The lotus leaf is able to repulse water with a remarkable efficiency transforming any drop of water into a ball following the laws of solid physics. This extraordinary property is due to the association of a hydrophobic chemical composition with a hierarchical texturing of its surface.This thesis focuses on the understanding of the physical principles governing the interaction of water drops on the surfaces of structured polymer films of FEP, PMMA and PET. Two technologies have been implemented for the production of hierarchical superhydrophobic surfaces: thermal nanoimprint lithography (NIL) and plasma etching. We have measured the contact angles and hysteresis of these structured surfaces in order to identify their Wenzel or Cassie-Baxter wetting state. We have attached particular importance to the development of manufacturing and characterization solutions on large surfaces.The anti-icing properties have been characterized and the role of condensation in the propagation of frost has been correlated with the surface texturing. In addition, we have highlighted the role of the electrostatic surface potential on frost delays. Finally, in view of the applicative potential of these surfaces, we added a dynamic dimension in the study considering the velocity of drops impact. A model of prediction from the literature was successfully compared to our experimental results.

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-07-31T19:16:12Z No. of bitstreams: 2 thiago_coimbra_pimenta.pdf: 3361101 bytes, checksum: 026e379b14e8e90fdfd54a1c94b5e25d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-08-14T15:21:20Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) thiago_coimbra_pimenta.pdf: 3361101 bytes, checksum: 026e379b14e8e90fdfd54a1c94b5e25d (MD5) / Made available in DSpace on 2017-08-14T15:21:20Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) thiago_coimbra_pimenta.pdf: 3361101 bytes, checksum: 026e379b14e8e90fdfd54a1c94b5e25d (MD5) Previous issue date: 2017 / A Dengue ? uma doen?a infecciosa viral de transmiss?o vetorial pelo mosquito Aedes aegypti, cujo controle tem se mostrado de solu??o complexa. Al?m disso, o diagn?stico cl?nico ? dif?cil de ser realizado, principalmente na fase aguda da doen?a, em que os sintomas s?o muito similares aos de outras infec??es febris agudas, e por essa raz?o o desenvolvimento de m?todos de detec??o mais efetivos para o seu controle, ganha relev?ncia. M?todos moleculares est?o sendo cada vez mais utilizados para o diagn?stico precoce por serem mais r?pidos e sens?veis. Nesse sentido, o uso de biossensores ganha relev?ncia por serem dispositivos vers?teis, de f?cil constru??o e utiliza??o, sens?veis e seletivos. Combinado com o uso de pol?meros modificadores da superf?cie transdutora, o que favorece a etapa de imobiliza??o das biomol?culas, os biodispositivos assim constru?dos se mostram mais sens?veis devido ? compatibilidade das caracter?sticas do elemento biol?gico e do filme polim?rico. Desta forma, este trabalho visou desenvolver um imunossensor impedim?trico para diagn?stico de Dengue utilizando eletrodos impressos de grafite (EI) funcionalizados com filmes polim?ricos derivados do ?cido 4-aminofenilac?tico (4-AFA). O imunossensor baseou-se na intera??o espec?fica entre o ant?geno da Dengue, a prote?na NS1, e os anticorpos anti-NS1. No estudo de caracteriza??o por voltametria c?clica (VC) da plataforma funcionalizada, observou-se que o filme polim?rico formado apresentou dois picos de oxida??o em +0,17 e +0,35 V em meio de solu??o de ?cido sulf?rico 0,50 M, o que mostra sua adsor??o e eletroatividade na superf?cie do eletrodo. Medidas de espectroscopia de imped?ncia eletroqu?mica (EIE) mostraram maior resist?ncia ? transfer?ncia eletr?nica do EI modificado com o filme polim?rico quando comparado ao EI sem modifica??o, corroborando o estudo anterior. Para o estudo de melhor concentra??o de NS1 para imobiliza??o, verificou-se que 1,00 ng/mL apresentou melhor sinal anal?tico, devido ? diminui??o nas intera??es que ocorre entre os ant?genos. O tempo de imunorrea??o entre ant?geno (Ag) e anticorpo (Ac) tamb?m foi estudado, no qual observou-se que o tempo ideal para que ocorra a imunocomplexa??o foi de 20 minutos. Em seguida, foi realizado estudo de dilui??o dos soros positivos e negativos por EIE, no qual foi poss?vel observar, para o soro positivo, que quanto mais dilu?do o soro maior foi o valor de Rct encontrado. O soro negativo tamb?m apresentou sinal anal?tico, provavelmente devido ? presen?a de anticorpos n?o espec?ficos, por?m, o sinal gerado apresentou valores mais pr?ximos do sinal da NS1, mostrando a seletividade da plataforma proposta. O estudo foi repetido em eletrodo sem modifica??o a fim de verifica a import?ncia do filme polim?rico na constru??o do biossensor. Observou-se que quando a NS1 ? imobilizada ao eletrodo n?o modificado, o Rct aumento muito pouco quando comparado ao eletrodo modificado com o filme derivado do 4-AFA, o que mostra a efici?ncia e sensibilidade da plataforma proposta. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / Dengue is a viral infectious disease transmitted by the Aedes aegypti mosquito, whose control has shown a complex solution. In addition, the clinical diagnosis is difficult to perform, especially in the acute phase of the disease, in which the symptoms are very similar to other acute febrile infections, and for this reason the development of more effective detection methods for its control gains relevance. Molecular methods are being increasingly used for early diagnosis because they are faster and more sensitive. In this sense, the use of biosensors gains relevance because they are versatile devices, of easy construction and use, sensitive and selective. Combined with the use of transducing surface modifying polymers, which favors a stage of immobilization of the biomolecules, the biodevices constructed in this way are more sensitive due to the compatibility of the biological element characteristics and the polymer film. Thus, this work aimed to develop an impedimetric immunosensor to Dengue diagnose using screen-printed electrode (SPE) functionalized with polymer films derived from 4-aminophenylacetic acid (4-APA). The immunosensor was based on the specific interaction between Dengue antigen, NS1 protein, and anti-NS1 antibodies, IgG e IgM. In characterization study by cyclic voltammetry (CV) of the functionalized platform, it has been observed that the polymer film shown two oxidation peaks in +0.17 and +0.35 V in 0,5 M sulfuric acid solution medium, which shows its adsorption and electroactivity at the SPE surface. Electrochemical impedance spectroscopy (EIS) measurements has shown a higher charge transfer resistance to the polymer film modified SPE when compared to the non-modified SPE, corroborating the previous study. For the study of NS1 best concentration to immobilization, it has been verified that 1,00 ng/mL presented better analytical signal, due to the decrease of the interactions that occur between the antigens. Immunoreaction time between antigens (Ag) and antibody (Ab) has also been studied, in which it has been observed that the ideal time for immunocomplexation was 20 minutes. Afterwards, a positive and negative sera dilution study was carried out by EIE, in which it has been possible to observe, for the positive serum, that the more diluted the serum the greater the Rct found. The negative serum also presented analytical signal, probably due to the presence of non-specific antibodies, however, the generated signal presented values closer to the NS1 signal, showing the selectivity of the proposed platform. The study was repeated in electrode without modification in order to verify the importance of the polymeric film in the biosensor construction. It was observed that when NS1 is immobilized to the non-modified electrode, Rct increases very little when compared to the 4-AFA derived film modified electrode, which shows the efficiency and sensitivity of the proposed platform.

Presented work is focused on the deposition and characterization of thin and ultrathin plasma polymer films, then also on the preparation of nanocomposites metal/plasma polymer. The characterization of plasma polymer films was partly done in-situ without exposing the samples to the atmosphere. The thickness of prepared films was measured by spectral ellipsometry, the chemical composition was measured by XPS. The morphology and optical properties of deposited films were measured ex-situ. It is shown that during the initial stages of growth the properties of plasma polymer films depend on their thickness and also on the material of the substrate. Many interesting applications were explored for prepared nanocomposites metal/plasma polymer. They can be used as superhydrophobic coatings, gradient coatings, substrates for Raman spectroscopy or as antibacterial coatings. Moreover, special optical properties of prepared nanocomposites were studied in detail. Presented work has an experimental character.

In the business of packaging engineering, a large consumption of time is placed on evaluating new materials to provide cost savings to a company. This evaluation is made by using test methods such as those found in ASTM D4169-16, which helps to simulate shipping and distribution conditions. A key problem is that this test method can take up to multiple months, and sometimes years to complete. The apparatus created in this study allows for a comparison to be made between currently used films and prospective films in approximately ten hours. This allows for a prescreening of new films to be done before completing full ASTM shipment and distribution testing.This study focuses on coextruded multilayer polymer films and the damage brought upon them in forms of puncture and abrasion through shipment and distribution.

Thin polymer materials are today widely used in industry and production. An ordinary food package can have around six different layers of materials laminated together to obtain the desired protection. To obtain an efficient usage of these materials simulations are often required. But the simulations require precise and good material models and properties. To obtain these properties through standard tests are difficult as normal strain gauges or extensometers can’t be used. Much research has been done on this kind of material. But still, the knowledge of the behaviour in certain cases is limited. One such area is the tearing of a laminated material.   The first objective of the work is to test a new measurement method, Digital Image Correlation (DIC), for thin polymer films and test if the method is applicable. DIC is a non-contact measurement technique that measure the deformation of a stochastic pattern. The strain is then calculated from this deformation. These strains can then be used to obtain material properties and behaviour. The second objective is to test the tearing behaviour of a laminate.   The material used is a laminate between a PET (100 μm) and LDPE (25 μm) film. When testing the single layers they were carefully delaminated with a plexiglass staff. As the material can be anisotropic the materials were tested in five directions: Machine Direction (MD); 22,5˚; 45˚; 67,5˚ and Cross Direction (CD). The work and tests were performed at BTH Campus Gräsvik.   An experimental setup for DIC with the usage of chalk spray and backlight was tested. Five tests were performed with and without DIC pattern. It was calculated that the DIC specimens were within standard deviation of the reference tests. GOM Correlate was used to evaluate the strains and visualise the distribution. The strains obtained were also used to calculate the true stress of the specimens and estimate the Poisson’s ratio.      Through testing it was concluded that the tearing of the laminate led to delamination in one of the legs. The delamination always appears in the leg where the LDPE film will experience tensile forces. The crack also angels towards 45˚. By testing single layers it was found that the PET film angles when teared, likely caused by the anisotropy of the material.      An experimental setup for the use of DIC for thin polymer has been developed. This method can be used for future measurements and improvement of material models. The behaviour of laminated tearing was observed and some conclusions could be drawn about its behaviour. However, a lot more work is required on this subject.

Organic bioelectronics develops electronic devices at the interface with living systems using organic electronic materials. These devices can identify various chemical species and regulate the operation of individual cells, tissues, or organs. A famous organic bioelectronic device is the organic electrochemical transistor (OECT), a highly versatile circuit component that has been used in applications spanning from biosensing to neuromorphic computing. OECTs can be operated in aqueous electrolytes and use organic mixed ionic-electronic conductors (OMIECs) in their channel (and sometimes as gate electrode coating) that can transport electronic and ionic charges, making them ideal for bridging biological systems and silicon-based electronic devices. Electron-transporting (n-type) OMIEC materials have received particular attention because high-performance n-type OECTs can be used to build inverters, sensors, and complementary amplifiers. However, electron transport in an aqueous and ambient environment under the application of electrical fields is a complex phenomenon that requires in situ investigation techniques. Understanding how films operate in such media can allow to construct novel sensors and eliminate the loss processes. This Ph.D. dissertation focuses on the impact of the environment, specifically oxygen, and light, on the performance of n-type OECTs and shows how to use this knowledge to develop OECT-based glucose sensors and photodetectors. Chapter 1 introduces the mixed charge transport phenomenon in conjugated polymers and how to use it in OECT operation. OECT fabrication and various designs are described, setting the ground for the sensors we will show in the following chapters. The experimental procedures used to evaluate the critical figures of merit of the materials and the transistor performance are described in detail. Chapter 2 introduces how OECTs can be used to transduce biochemical binding events. When employing the OECT platform for biochemical sensing, it is essential to differentiate between the faradaic, capacitive, and potentiometric contributions to the sensor response. Understanding the underlying mechanisms is critical for optimizing performance. This chapter explains these different sensing mechanisms with literature examples. Chapter 3 compiles all experimental details relevant to the investigations presented in Chapters 4 and 5. Chapter 4 investigates the working mechanism of a novel n-type OECT-based glucose sensor relying on an enzymatic reaction. This chapter shows the oxygen reaction reactions and the importance of monitoring contact potentials during device operation to understand how detection occurs. The work unveils the role of the oxygen sensitivity of the n-type material on the sensor operation and suggests paths to improve performance. Chapter 5 explores the interactions of light with n-type OMIECs and how to utilize them to build water-compatible phototransistors. The first part of the chapter involves a characterization of the light/matter interplay of an n-type film and a demonstration of how to use it to build a photoelectrochemical transistor. The second part of the chapter expands this work to other n-type materials and assesses their light sensitivity, building a relationship between material property and device performance. Since most detection events lead to a change in the surface of materials, techniques that monitor surface roughness and profile changes in situ can be useful. Chapter 6 describes an atomic force microscopy (AFM) setup that can be used to investigate binding events and electrochemical doping and de-doping dynamics of OMIEC films. This chapter is intended to assist researchers in developing in-operando AFM procedures studying OMIEC films.

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No description available.

The global market for fluoropolymers, including polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), is growing rapidly due to their copious applications in the construction, automotive, medical, chemical, and electrical industries. Fluoropolymers owe their popularity partly to their excellent chemical and thermal stability and useful mechanical, piezoelectric, and ferroelectric properties. They are made into films or coatings that are used for corrosion protection or surface property enhancement. Electrophoretic deposition (EPD) has generated increasing interest in manufacturing advanced films for various applications due to its low cost, versatility, simple apparatus, and good film quality compared with other deposition techniques like dip coating, spin coating, electrospinning, or spay coating. Moreover, EPD facilitates uniform deposition on the substrates of complex shapes at a high deposition rate. The aim of this research is to develop novel biomimetic strategies for fabricating polymer films and their composite films with multifunctional particles through EPD. This method involves the electrophoresis of charged particles in a stable colloidal suspension towards an electrode, forming deposition. Fluoropolymers, however, are electrically neutral and chemically inert, and their EPD presents difficulties. Therefore, successful EPD depends on understanding how to modify the surface of polymer particles using advanced biosurfactants to impart charge and form a well dispersed, stable colloidal suspension. One strategy is to leverage the unique dispersing power of bile acids and salts as biosurfactants for EPD of PTFE and PVDF films and composite films. When doing so, it was found that the amphiphilic structure of bile salts such as sodium deoxycholate (DChNa) facilitated adsorption on the chemically inert, hydrophobic surfaces of PTFE, diamond, and carbon dots. In this strategy, DChNa acted as a charging, dispersing, film-forming agent for the co-deposition of PTFE composite films from an aqueous suspension. Water insoluble bile acids (BAs) were found to be biosurfactants for the EPD of PTFE and PVDF from organic solvents, in which lithocholic acid (LCA) was used as a co-dispersant for the fabrication of composite PTFE-diamond coatings and PTFE coatings provided corrosion protection for stainless steel in 3% NaCl solutions. The dispersing performance of four other bile acids, chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and cholic acid (ChA), was analyzed and compared with LCA on the deposition performance of PVDF. It was found that the PVDF deposition yield obtained using different BAs increased in the order of LCA<CDCA<DCA<UDCA<ChA. This was attributed to the difference in number, position, and orientation of OH groups in the structures of the BAs. Another biomimetic strategy for the EPD of polymers and composites was inspired by the strong adsorption of mussel protein on rock surfaces in sea water. Catecholate-type molecules, caffeic acid (CA) and catechol violet (CV), were found to be biosurfactants for dispersing, charging, and depositing PVDF films and composites. Analyses of the deposition yield data, the chemical structure of the CA and CV, and the microstructure and composition of the films suggested that the aromatic rings on the CA and CV had hydrophobic interactions with the PVDF particles and that the phenolic groups formed bidentate chelating or bridging bonding to inorganic particle surfaces. The study demonstrated the feasibility of co-depositing PVDF with nanoparticles of TiO2, MnO2, and NiFe2O4. CA was also used for preparing PVDF-HFP particles and as a co-dispersant for the co-deposition of PVDF-HFP with NiFe2O4 and CuFe2O4 nanoparticles in order to make composite films that combine the ferrimagnetic properties of spinel ferrites with the multifunctional properties of ferroelectric polymers. / Dissertation / Doctor of Philosophy (PhD)