No description available.

The problems and high medical costs associated with chronic wounds necessitate an economical bioactive wound dressing. A new strategy was investigated to inhibit MMP-9 proteases and to release epidermal growth factor (EGF) to enhance healing. Doxycycline (DOX) and EGF were encapsulated on polyacrylic acid modified polyurethane film (PAA-PU) using Layer-by-Layer (LbL) assembly. The number of bilayers tuned the concentration of DOX and EGF released over time with over 94% bioactivity of EGF retained over 4 days. A simple wound model in which MMP-9 proteases were added to cell culture containing fibroblast cells demonstrated that DOX inhibited the proteases providing a protective environment for the released EGF to stimulate cell migration and proliferation at a faster healing rate. In the presence of DOX, only small amounts of the highly bioactive EGF are sufficient to close the wound. Results show that this is new and promising bioactive dressing for effective wound management.

The problems and high medical costs associated with chronic wounds necessitate an economical bioactive wound dressing. A new strategy was investigated to inhibit MMP-9 proteases and to release epidermal growth factor (EGF) to enhance healing. Doxycycline (DOX) and EGF were encapsulated on polyacrylic acid modified polyurethane film (PAA-PU) using Layer-by-Layer (LbL) assembly. The number of bilayers tuned the concentration of DOX and EGF released over time with over 94% bioactivity of EGF retained over 4 days. A simple wound model in which MMP-9 proteases were added to cell culture containing fibroblast cells demonstrated that DOX inhibited the proteases providing a protective environment for the released EGF to stimulate cell migration and proliferation at a faster healing rate. In the presence of DOX, only small amounts of the highly bioactive EGF are sufficient to close the wound. Results show that this is new and promising bioactive dressing for effective wound management.

In the research described in this thesis, two molecular layers were successfully anchored on carbon surfaces (pyrolyzed photoresist films, PPFs) sequentially through two independent approaches. The first molecular layer, styrene, was covalently bonded on PPF surfaces via the method of reduction of in situ generated diazonium ions. The resulting molecular films were characterized by AFM measurements, and catechol and ferrocyanide voltammetry. The second molecular layer, ferrocene-thiol, was anchored on top of the first molecular layer through the method of thiol-ene reaction, which is an effective method for building up multilayers through layer-by-layer assembly. As ferrocene is an electrochemically active species, quantitative surface coverage was calculated according to the amount of surface-bound ferrocene through electrochemical measurements. Finally, molecular junctions were fabricated by depositing metal top contacts based on the molecular layers through electron-beam evaporation and the electronic characteristics of these molecular junctions were investigated.

Orientador: Marystela Ferreira / Resumo: Neste trabalho foram desenvolvidos diferentes tipos de filmes Layer-by-Layer (LbL) sensíveis a variação de pH, temperatura, exposição a luz e presença de carboidratos, com o objetivo de criar sistemas com resposta a estímulos que podem ser aplicados na área médica e ambiental para a entrega modificada de fármacos e pesticidas. O trabalho foi dividido em três partes, sendo o primeiro focado na liberação da emodina. Foram fabricados filmes com a emodina imobilizada diretamente e outra em que o fármaco foi encapsulado nos lipossomos formados por dipalmitoil fosfatidil glicerol (DPPG) e palmitoil fosfatidil glicerol (POPG) e então intercalado com polieletrólitos. Ambos os filmes foram expostos a condições fisiológicas e liberaram a emodina por um período prolongado em função da mudança de pH e temperatura. A segunda parte do trabalho é focado na construção de filmes com um polímero baseado em espiropirano (poli(SP-R)), um composto que quando recebe luz UV é convertido para a forma aniônica merocianina (poli(MC-R)) mudando sua cor e carga superficial. O filme foi composto pelo policátion poli(alilamina hidroclorada) (PAH) formando o (PAH/poli(SP-R))n que se desprendeu do substrato pelo processo disassembly após longo tempo de exposição à luz branca. Na terceita parte do trabalho foram desenvolvidos filmes com o polímero baseado em ácido fenil borônico (PBA), que tem a capacidade de se ligar covalentemente à açucares. Foram fabricados intercalado com PVS resultando no filme (PEI/PV... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work, we developed some types of Layer-by-Layer (LbL) films sensible to pH and temperature changes, light exposition and carbohydrates solutions, with the aim of to create stimuli responsive system that can be applied to medical and environmental area to drug and pesticide modulated delivery. The work was divided in three parts, the first one is based on delivery emodin. One film was fabricated with emodin immobilized directly and other the drug was encapsulated on liposomes formed by dipalmitoyl phosphatidyl glycerol (DPPG) e palmitoyl phosphatidyl glycerol (POPG) and the carrier was intercalated with polyelectrolytes. Both systems were exposed to physiologic conditions and released the emodin for prolonged time in function of pH and temperature changes. On second part of this work it was focused on construction of film with spyropiran (SP) based polymer (poli(SP-R)). The UV irradiation over (poli(SP-R)) causes the conversion to anionic and purple merocyanine molecule (poli(MC-R)) changing the color and surface charge. The film were composed by poly(allylamine hydrochloride) (PAH) and poly(SP-R) forming the (PAH/poli(SP-R))n LbL film which disassemble after long time exposed to white light. On third part of work, films were developed with phenyl borônico acid (PBA) based polymer that has the capacity to bind covalently on sugars. The films were intercalated with PVS creating the coating (PEI/PVS)2(PBAp/PVS)n. It were prepared also a film with the pyranine (PYR), the ... (Complete abstract click electronic access below) / Doutor

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-09-21T19:51:20Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-10-09T13:37:54Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) / Made available in DSpace on 2017-10-09T13:37:54Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) Previous issue date: 2017 / Neste trabalho, Carbon Dots (CDs) obtidos a partir de celulose de algod?o e contendo 4,5 mmol.g-1 de grupos funcionais ?cidos, dos quais 63 % exibiam pKas t?picos de ?cidos carbox?licos foram usados na prepara??o de filmes automontados com os biopol?meros quitosana (QT) e col?geno (CL) a fim de verificar a morfologia, espessura e intera??es moleculares entre os componentes. A quitosana usada apresentou um total de 4,2 mmolg-1 de grupos funcionais -NH2, correspondente a um grau de desacetila??o de ~70 %. Por outro lado, o col?geno hidrolisado apresentou diferentes grupos funcionais com acidez de Br?nsted, t?picos da presen?a de diferentes amino?cidos na estrutura. Todos os filmes finos foram preparados com a t?cnica de deposi??o camada por camada (do ingl?s: Layer-by-layer (LbL)) por meio de imers?o do substrato nas diferentes solu??es. Os materiais foram caracterizados por diferentes t?cnicas, incluindo Microscopia de For?a At?mica, Espectroscopia na regi?o do UV-Vis, Espectroscopia de Resson?ncia de Plasma de Superf?cie e Titula??o Calorim?trica. Em todas as condi??es experimentais utilizadas para o crescimento dos filmes, observou-se um crescimento linear da quantidade de material depositado com o n?mero de imers?es realizadas. No entanto, diferentes condi??es das solu??es dos biopol?meros e da suspens?o de Carbon Dots produziram filmes com espessura e morfologia diferentes. Nos filmes de QT/CDs a quantidade de nanopart?culas depositadas por bicamada, com solu??o de quitosana em pH = 3,5, pH = 5 e pH = 3,5 na presen?a de 0,1 mol/L de NaCl, foram, respectivamente, 11 mg.m-2, 16 mg.m-2 e 24 mg.m-2 sendo as espessuras dos filmes, com 20 bicamadas, correspondentes a estas quantidades foram de 60, 150 e 200 nm. Este resultado ? atribu?do ao aumento da flexibilidade das cadeias polim?ricas dos biopol?meros, as quais est?o menos carregadas. Dessa forma, as cadeias podem apresentar conforma??es mais adequadas para recobrir eficientemente a estrutura das nanopart?culas quase esf?ricas. Al?m disso, o aumento da for?a i?nica da solu??o de Carbon Dots tamb?m contribui para o aumento de material depositado devido ? forma??o de aglomerados sob estas condi??es. Nos filmes de CL/CDs, a quantidade de nanopart?culas depositadas, com solu??o de col?geno em pH = 3,16, pH = 5 e pH = 3,16 na presen?a de 0,1 mol/L de NaCl, foram 2,3 mg.m-2, 6,46 mg.m-2 e 6,41 mg.m-2, respectivamente. No entanto, a energia de intera??o, obtida por calorimetria isot?rmica, ? maior em pH baixo. Em geral, a quantidade de material depositado nos filmes de col?geno ? bem inferior ?s observadas para os filmes de QT/CDs e, consequentemente, filmes com espessuras entre 40 e 50 nm. Al?m disso, n?o foi observada varia??o significativa entre as massas depositadas nestes filmes com o aumento do pH e for?a i?nica. Estes resultados podem estar relacionados ? menor ?carga parcial positiva? sobre as cadeias da prote?na em rela??o a quitosana, observada pelos potenciais zeta nestas condi??es. Por fim, os resultados aqui apresentados sugerem que as estruturas dos filmes, isto ?, morfologia e espessura, podem ser facilmente controladas e reproduzidas manipulando-se as condi??es das solu??es dos biopol?meros, al?m do tradicional n?mero de imers?es. Em adi??o, o estudo pode contribuir para o desenvolvimento de uma nova classe de dispositivos de alto desempenho, como sensores e superf?cies fotoativas. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / In the present work, Carbon Dots (CDs), obtained from cotton cellulose and containing 4.5 mmol g-1 of acid functional groups, of which 63% exhibited typical pKa?s compared to carboxylic acids, were used in the preparation of self-assembled films with the biopolymers Chitosan (QT) and Collagen (CL) in order to verify the morphology, thickness and molecular interactions among the components. The chitosan used in this work had a total of 4.2 mmol g-1 of functional groups ?NH2, corresponding to a deacetylation degree of ~70%. On the other hand, the hydrolyzed collagen showed different functional groups with Br?nsted acidity typical to the presence of different amino acids in the structure. All the thin films were prepared using the Layer-by-layer method (LbL) by immersing the substrate in different solutions. The materials were characterized by several techniques, such as Atomic Force Microscopy, UV-Vis Spectroscopy, Surface Plasmon Resonance and Calorimetric Titration. It was observed, in all experimental conditions for the growth of the films, a linear increase in the amount of deposited material with the number of immersions performed. However, different conditions of the biopolymer solutions produced films with different thickness and morphology. In the films QT/CDs the amount of nanoparticles deposited per bilayer, with the chitosan solution at pH = 3.5, pH = 5 and pH = 3.5 with the presence of 0.1 mol L-1 of NaCl, were, respectively, 11 mg m-2, 16 mg m-2 and 24 mg m-2 with the thickness of the film, at 20 bilayers, at 60, 150 and 200 nm. This result is associated to the increase in the flexibility of the polymeric chains of the biopolymers, which are less charged. Thus, the chains can present conformations that are proper to cover more efficiently the structure of the almost spherical nanoparticles. Furthermore, the increase of the ionic strength of the Carbon Dots solution also contributes to the increase of the material deposited due to the formation of agglomerates in these conditions. In the films CL/CDs, the amount of nanoparticles deposited, with the collagen solution at pH = 3.16, pH = 5 and pH3.16 in the presence of 0.1 mol L-1 of NaCl, were 2.3 mg m-2, 6.46 mg m-2 and 6.41 mg m-2, respectively. However, the interaction energy, obtained by isothermal calorimetry, is higher in low pH. In general, the amount of material deposited on the collagen films is much lower than that observed for the QT/CDs films and, consequently, films thickness are 40 and 50 nm. Besides that, it was not observed any significant variation between the masses deposited in these films with the increase of the pH and the ionic strength. These results may be associated to the lower ?partial positive charge? on the protein chains in relation to the chitosan, observed by the zeta potentials in these conditions. The presented results suggest that the structures of the films, i.e. morphology and thickness, can be easily controlled and reproduced manipulating the conditions of the biopolymer solutions and the number of immersions. Additionally, the study may contribute to the development of a new class of high performance devices, such as sensors and photoactive surfaces.

A técnica de automontagem [Self-Assembly (SA)] tem sido largamente empregada na fabricação de estruturas supramoleculares de polímeros condutores que requerem controle molecular. O paradigma implícito no método de automontagem é a adsorção espontânea de camadas carregadas com cargas opostas, conduzindo assim a um filme de multicamadas formado pela alternância de policátions e poliânions. Nesta dissertação, são empregados dois tipos de polímeros conjugados e seus derivados que são identificados por suas famílias, que são a da polianilina (PAn) e a do poli(pfenileno vinileno) (PPV). São enfatizados os processos de adsorção para as polianilinas e precursores do PPV, propondo-se um mecanismo de adsorção não autolimitada sustentado por condições de não equilíbrio. O processo não autolimitado comprova que a adsorção pode ser controlada por outras interações que não a eletrostática, como as pontes de hidrogênio que são comuns nas polianilinas, e/ou por interações típicas de dispersões coloidais, visto que os polímeros se agregam em solução. Este novo método pode ter grande impacto na fabricação de estruturas supramoleculares porque podem ser obtidos filmes espessos de uma única camada com controle em nível molecular. A desvantagem deste método está na obtenção de filmes não uniformes, propriedade que ainda não é adequadamente controlada. A investigação da formação de filmes de múltiplas camadas e dos processos de fluorescência para filmes de bicamadas e não autolimitados é apresentada e discutida em função dos trabalhos da literatura. Finalmente, são correlacionados os processos de adsorção e a fluorescência / The self-assembly (SA) technique has been widely used for producing supramolecular structures fi-om conducting polymers, in which molecular control may be achieved. The paradigm implicit in the SA method is the spontaneous adsorption of oppositely charged layers, thus leading to a multilayer film containing polycations alternated with polyanions. In this dissertation, two types of polymer are employed in the fabrication of SA films, namely polyanilines and poly(p-phenylene vinylenes) (PPVs). For the polyanilines, emphasis was placed in the adsorption processes, where it is proposed that a non-self-limiting process may be achieved if adsorption is carried out under non-equilibrium conditions. A non-self-limiting process is proof that adsorption is not entirely controlled by electrostatic interactions, but may also depend on H-bonding which is very efficient in polyanilines and on interactions typical of colloid dispersions as the polymers aggregate while in solution. This nove1 method may have a large impact in the fabrication of supramolecular structures because much thicker films may be obtained in a single layer. The disadvantage of this method, however, lies in the fabrication of non-uniform films which cannot be controlled adequately. The investigation of the fabrication of multilayers and of fluorescence processes in films built with bilayers and via non-self-limiting adsorption is presented and discussed in terms of work published in the literature. Finally, the processes of adsorption and fluorescence are correlated

No description available.

No description available.

No description available.