Made available in DSpace on 2014-06-11T19:25:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-22Bitstream added on 2014-06-13T18:47:24Z : No. of bitstreams: 1 scapin_cl_me_araiq.pdf: 2270317 bytes, checksum: 3319493efcc2a0eb1eb0b2d298e9f726 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do presente estudo foi avaliar in vitro, utilizando-se cultura de células osteoblásticas MC3T3-E1, a interação da superfície da liga Ti-15Mo usinada, com irradiação por feixe de laser sem e com recobrimento de apatitas obtidas pelo método biomimético, empregando-se solução SBF(Simulated Body Fluid) padrão e SBF modificada. As superfícies obtidas foram caracterizadas por Microscopia Eletrônica de Varredura (MEV), Difração de raios X (DRX), medidas de ângulo de contato e a camada de apatita foi avaliada também por Espectroscopia no Infra Vermelho Transformada de Fourier (FTIR). As avaliações in vitro foram realizadas utilizando as superfícies: usinada (U), modificada por feixe de laser (LA), modificada por laser e recoberta com SBF padrão (HA) e modificada por laser e recoberta com SBF modificada (AP). Os parâmetros biológicos avaliados foram: adesão, proliferação, contagem do número de células e conteúdo de proteína total. A morfologia celular, adesão e proliferação foram avaliadas por MEV, e a contagem de células utilizando-se hemocitômetro e azul de Tripan. Os estudos indicaram que o grupo AP apresentou os melhores resultados em relação à adesão, proliferação e contagem do número de células, seguido pelo grupo HA, LA e U respectivamente. Nas análises de conteúdo de proteína total, após 14 dias de cultura, o grupo LA obteve o melhor resultado, seguido por AP, HA e U respectivamente. Portanto, pode-se concluir que a modificação da superfície da liga Ti- 15Mo por feixe de laser, seguida do emprego do método biomimético utilizando-se solução SBF modificada possibilitou a obtenção de condições biológicas favoráveis para aplicação desta liga como dispositivo ortopédico e odontológico / The aim of this study was the in vitro evaluation of interaction surface, using cell culture osteoblastic MC3T3-E1, on Ti-15Mo alloy with machined surface, and with the surface modified by laser beam irradiation with and without coating of apatite obtained by biomimetic solution SBF (Simulated Body Fluid) standard and modified. The surfaces were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), measurements of contact angle and the layer of apatite was also evaluated by Fourier Transform Infrared Spectroscopy (FTIR). Evaluations were performed in vitro using the machined surfaces (U), modified by laser beam (LA), modified by laser and covered with standard SBF (HA) and modified by laser and covered with modified SBF (AP). The parameters evaluated were: adhesion, counting the number of cells and total protein content. Cell morphology, adhesion and proliferation were evaluated by SEM, and the cell count using hemocytometer and Trypan blue. The results indicated that the AP group showed better results of adhesion, proliferation and counting the number of cells, followed by the group HA, LA and U respectively. In the analysis of total protein content, after 14 days of culture, the LA group had the best result, followed by AP, HA and U respectively. Based on these results, it can be concluded that the modification on Ti- 15Mo alloy using laser beam irradiation, followed by biomimetic method for surface coating using SBF modified solution showed favorable biological conditions for application and development of orthopedic and dental devices

Orientador: Carlos José Leopoldo Constantino / Coorientador: José Carlos Silva Camargo Filho / Banca: Neri Alves / Banca: William Dias Belangero / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caracter institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Este trabalho tem como objetivo o desenvolvimento de blendas poliméricas a base de polímeros sintéticos e amido para a obtenção de materiais biocompatíveis que possam ser utilizados como matrizes em processos de regeneração óssea. Os materiais utilizados foram o poli(fluoreto de vinilideno) (PVDF), o poli(fluoreto de vinilideno com trifluoretileno) P(VDF-TrFE) e o amido de milho. Foram elaboradas blendas de PVDF/amido nas proporções em massa de 90/10, 80/20 e 66/33 e P(VDF-TrFE)/amido na proporção de 66/33. As blendas foram fabricadas em formato cilíndrico para permitir, posteriormente, testes in vivo através do implante em ratos. O processo de fabricação das blendas foi o de prensagem (2 ton) a quente, com temperaturas de 155ºC e 190ºC para o P(VDF-TrFE)/amido e PVDF/amido, respectivamente. Na investigação das propriedades físicas e químicas das blendas poliméricas utilizaram-se as seguintes técnicas de caracterização: espectroscopia via espalhamento micro-Raman, espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR), análise dinâmico-mecânica (DMA) e microscopia eletrônica de varredura (MEV). Após a fabricação das amostras estas foram submetidas a testes in vitro sob a ação da enzima amilase por períodos de 14,28 e 42 dias. A espectroscopia vibracional revelou a ausência de interação química entre os polímeros e amido (mistura física) e que o processo de prensagem a quente não produziu qualquer tipo de degradação destes materiais. As próprias fases a e ferroelétrica do PVDF e P(VDF-TrFE) em pó, respectivamente, foram mantidas nas blendas. As imagens de MEV das blendas apresentaram poros no região externa, o que foi atribuída à perda de amido no processo de retirada das amostras dos moldes. Além disso, foram percebidas regiões distintas de materiais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work aims at the development of polymer blends based on synthetic polymers and starch to obtain biocompatible materials that can be used as matrices in the process of bone regeneration. The materials used were poly(vinylidene fluoride) (PVDF), poly(vinylidence fluoride with trifluoretileno) P(VDF-TrFE) and com starch. It was prepared blends of PVDF/starch mass ratio in 90/10, 80/20 and 66/33 and P(VDF-TrFE)/starch at a ratio of 66/33. The blends were made in a cylindrical shape to allow for later testing in vivo in rats by implanting. The manufacturing process of the blends was compressing (2 ton) under heating, with temperatures at 155ºC and 190ºC for P(VDF-TrFE)/starch and PVDF/starch, respectively. In the investigation of physical and chemical properties of polymer blends the following characterization techniques were used: Raman scattering spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). After the fabrication of these samples, essays were carried out in vitro under the action of the enzyme amilase for 14,28 and 42 days. The vibrational spectroscopy revealed no chemical interaction between the polymers and starch (physical mixture) and that the process of compressing under healting did not produce any degradation of these materials. Even the a phase and the ferroelectric phase of PVDF and P(VDF-TrFE) powder, respectively, were kept in the blends. SEM images of the blends showed pores in the outer region, which was atributed to the loss of starch in the process of withdrawal of samples from the molds. In addition, distinct regions were observed for the blends, i.e. PVDF or P(VDF-TrFE) and starch are separated, allowing the identification of each material (starch acts as a filler). In the optical images obtained by micro-Raman the same... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-13Bitstream added on 2014-06-13T20:40:11Z : No. of bitstreams: 1 pereira_jdas_me_bauru.pdf: 2994314 bytes, checksum: c387c9f2ccba11fe66218fba65db31f1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho tem como objetivo o desenvolvimento de blendas poliméricas a base de polímeros sintéticos e amido para a obtenção de materiais biocompatíveis que possam ser utilizados como matrizes em processos de regeneração óssea. Os materiais utilizados foram o poli(fluoreto de vinilideno) (PVDF), o poli(fluoreto de vinilideno com trifluoretileno) P(VDF-TrFE) e o amido de milho. Foram elaboradas blendas de PVDF/amido nas proporções em massa de 90/10, 80/20 e 66/33 e P(VDF-TrFE)/amido na proporção de 66/33. As blendas foram fabricadas em formato cilíndrico para permitir, posteriormente, testes in vivo através do implante em ratos. O processo de fabricação das blendas foi o de prensagem (2 ton) a quente, com temperaturas de 155ºC e 190ºC para o P(VDF-TrFE)/amido e PVDF/amido, respectivamente. Na investigação das propriedades físicas e químicas das blendas poliméricas utilizaram-se as seguintes técnicas de caracterização: espectroscopia via espalhamento micro-Raman, espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR), análise dinâmico-mecânica (DMA) e microscopia eletrônica de varredura (MEV). Após a fabricação das amostras estas foram submetidas a testes in vitro sob a ação da enzima amilase por períodos de 14,28 e 42 dias. A espectroscopia vibracional revelou a ausência de interação química entre os polímeros e amido (mistura física) e que o processo de prensagem a quente não produziu qualquer tipo de degradação destes materiais. As próprias fases a e ferroelétrica do PVDF e P(VDF-TrFE) em pó, respectivamente, foram mantidas nas blendas. As imagens de MEV das blendas apresentaram poros no região externa, o que foi atribuída à perda de amido no processo de retirada das amostras dos moldes. Além disso, foram percebidas regiões distintas de materiais... / This work aims at the development of polymer blends based on synthetic polymers and starch to obtain biocompatible materials that can be used as matrices in the process of bone regeneration. The materials used were poly(vinylidene fluoride) (PVDF), poly(vinylidence fluoride with trifluoretileno) P(VDF-TrFE) and com starch. It was prepared blends of PVDF/starch mass ratio in 90/10, 80/20 and 66/33 and P(VDF-TrFE)/starch at a ratio of 66/33. The blends were made in a cylindrical shape to allow for later testing in vivo in rats by implanting. The manufacturing process of the blends was compressing (2 ton) under heating, with temperatures at 155ºC and 190ºC for P(VDF-TrFE)/starch and PVDF/starch, respectively. In the investigation of physical and chemical properties of polymer blends the following characterization techniques were used: Raman scattering spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). After the fabrication of these samples, essays were carried out in vitro under the action of the enzyme amilase for 14,28 and 42 days. The vibrational spectroscopy revealed no chemical interaction between the polymers and starch (physical mixture) and that the process of compressing under healting did not produce any degradation of these materials. Even the a phase and the ferroelectric phase of PVDF and P(VDF-TrFE) powder, respectively, were kept in the blends. SEM images of the blends showed pores in the outer region, which was atributed to the loss of starch in the process of withdrawal of samples from the molds. In addition, distinct regions were observed for the blends, i.e. PVDF or P(VDF-TrFE) and starch are separated, allowing the identification of each material (starch acts as a filler). In the optical images obtained by micro-Raman the same... (Complete abstract click electronic access below)

L’hydroxyapatite est un biomatériau bioactif largement utilisé pour la réparation et la reconstruction des défauts osseux, cependant, son efficacité est souvent limitée par sa faible densité. Le présent travail constitue une nouvelle contribution à l’étude des biocéramiques compacts nanostructurés qui sont considérés comme étant des matériaux facilement implantables au niveau osseux et dentaire. Des nanoparticules anisotropes d’hydroxyapatites ont été synthétisées par hydrolyse forcée en milieu polyol, en vue d’améliorer les caractéristiques mécaniques des biocéramiques apatitiques. Les nanopoudres obtenues ont été consolidées par le processus non-conventionnel tel que le frittage flash (spark plasma sintering, SPS) aboutissant à des massifs d’hydroxyapatites nanostructurés 3D. Ces derniers ont montré des performances morphologiques similaires à celles utilisés dans l’industrie, d’autre part, elles ont montré des performances mécaniques améliorées avec une dureté allant jusqu’à 9 GPa. / Hydroxyapatite is a biomaterial bioactive largely used for the reparation and the reconstruction of the bone and dental defects. However, the performance of the hydroxyapatite is limited by its low density. The present work forms a new contribution in the study of compact nanostructured biomaterials. These later are considered as facile implantable materials to bones ant dents. Anisotropic nanoparticle hydroxyapatites were synthesized by forced hydrolysis in a polyol medium in order to ameliorate the mechanic characteristics of bioceramic hydroxyapatites. The obtained nanopowders were consolidated by the nonconventional process spark plasma sintering (SPS) resulting to 3D nanostructure massive hydroxyapatites. The morphological performances were found to be similar to that which used in industries. On the other hand, the elaborated massive nanostructures have shown an ameliorated mechanical performance with 9 GPa hardness.

Membrane sacs, known as vesicles and liposomes have been widely used as stores for bioactive materials both in vitro and in vivo. The vesicles are biocompatible and in vitro experiments often use them in conjunction with magnetic nanoparticles. The magnetic nanoparticles allow the liposomes to be magnetically located and act as a trigger for release of the encapsulated materials. However, these magnetic vesicles or 'magnetoliposomes' as they are also known have not mananged to cross the barrier into clinical use. The work in this thesis aims to develop a novel system of magnetoliposomes for use in a biological environment. Magnetoliposomes are created from phospholipid suspensions extruded to give a spherical bilayer membrane. This membrane is doped with biotinylated lipids. These lipids are key to allowing the system to work in vitro. The magnetic nanoparticles are formed from iron and are coated with a novel synthetic linker to allow them to interact with the liposomes. When the liposomes and the nanoparticles are mixed in the presence of the protein avidin, large heirarchacal structures are formed which are stable under physiological conditions. The magnetoliposomes are held in an alginate hydrogel scaffold which acts as a support for the liposomes and as an adherent cell scaffold for tissue culture. This work demonstrates that this system can be used to encapsulate and release a range of bioactive molecules such as nickel chloride as a mimic for cytotoxic cancer drugs, ascorbic acid-2-phosphate for the upregulation of collagen production in chondrocytes and SB 431542 for the differentiation of mouse embryonic stem cells. The results shown in this work demonstrate that it is possible to use this novel linking system to create a new form of magnetoliposomes which are stable, biocompatible and easy to form and use. This work also demonstrates a strong model for possible drug delivery in vivo.

Myocardial infarction (MI) leads to permanent loss of cardiac muscle due to the limited regenerative potential of the mammalian heart. The affected heart muscle is replaced by a fibrotic scar; however, the scar is not able to offset the increase in wall stress placed on the remaining myocardium. This distending pressure can lead to dilative remodeling of the ventricle, progressive loss of cardiac function, and heart failure. Despite current medical therapy, heart failure continues to have a high mortality rate. Therefore, there is a clinical need for treatments that can both improve cardiac function post-MI and reduce ventricular remodeling to prevent progression to heart failure. Injectable biomaterials aim to provide a scaffold to stimulate infarct repair by mimicking the healthy cardiac extracellular matrix (ECM). The ECM plays a critical role in tissue regeneration but after a MI it is pathologically modified. Injection of biomaterials post-MI can provide a scaffold that better stimulates infarct repair. In this study, hydrogels were developed from recombinant human type I and type III collagen (rHCI and rHCIII), the two most prevalent structural proteins in the cardiac ECM. Injection of rHCI and rHCIII hydrogels in a mouse model of MI improved cardiac function and reduced infarct size 28 days post-treatment. Infarcted hearts treated with rHCI exhibited improved myocardial salvage in the region bordering the scar with improved capillary density. rHCI hydrogel was also superior to rHCIII in reducing ventricular remodeling. The injection of rHCI hydrogel into the border zone post-MI resulted in an acute improvement of contractile function two days after treatment that was maintained long-term. At two days post-injection, rHCI treated animals had reduced apoptotic cardiomyocytes and lower levels of oxidative stress. Methylglyoxal modifies and crosslinks collagen in the ECM, leading to oxidative stress. Two days after injection, the rHCI hydrogel at the epicardial surface was modified by methylglyoxal, while methylglyoxal-derived advanced glycation end-product levels in the underlying myocardium were lower than in control animals. It appears that rHCI hydrogel injection is soaking up free methylglyoxal from the myocardium, reducing levels of oxidative stress in cardiac muscle and improving contractility of cardiomyocytes bordering the scar. These results suggest that rHC therapy is a promising approach to improve cardiac contractility, and limit ventricular remodeling post-MI.

Currently, around 28 million people globally suffer from the consequences of corneal blindness and most of them are part of a long waiting list; availability of donor tissue is highly limited. Furthermore, even those who are treated are in risk of developing post- surgery complications, mainly due to microbial infections. Hence, cell-free biomaterials with enhanced properties to prevent corneal associated infections would provide a safe alternative. We evaluated the efficacy of different peptides for the functionalization of collagen-based hydrogels through the in situ synthesis of silver nanoparticles (AgNPs). The produced biomaterials were characterized and evaluated in vitro for biocompatibility and potential antimicrobial activity. From the diverse strategies evaluated, the localized formation of AgNPs onto the periphery of cornea-shaped collagen hydrogels may represent a more promising option.

Recent advances in the miniaturization of biosensors and drug delivery systems have allowed for the continuous and non-invasive monitoring of patient health. While sutures are mainly used for approximating tissues in clinical practice, there has been emerging development of new suture materials for improving wound healing outcomes. We report a novel method of continuous and high-throughput fabrication of multifunctional sutures and threads which allows for control over a wide range of important microstructural and physical properties. In the proposed fabrication method, a thread or suture is spooled across a base collecting plate. The fabrication method involves direct electrospinning (ES) onto the surface of threads and sutures. ES has also been widely used within the area of biomedical and tissue engineering, given its compatibility with a range of synthetic and natural biocompatible polymers. As the thread moves beneath a syringe pump and a spinerette needle that is positively charged, electrospun nanofibers collect on the surface of the thread. The coating layer thickness and the alignment of the nanofibers with the direction of the thread is tuned by varying the spooling speed and the distance between the spinerette needle and the thread. The resulting smart sutures have applications in both passive and on-demand drug release, durable wound biosensing, and improved cell viability and attachment. These structures may be manipulated in different materials (i.e. skin, fabrics, wound dressings) and be combined using textile methods (e.g. braiding, weaving, knitting) to form three dimensional (3D) constructs. / Graduate / 2022-09-10

Corneal perforations are medical emergencies in which the cornea is partially or completely ruptured, resulting in the loss of stability of the whole eye. Such situations can be caused by bacterial or fungal keratitis, autoimmune, or ocular-surface related disorders. Corneal perforations, if left untreated, can cause partial or total blindness. Therefore, immediate treatment is necessary. The best treatment available is corneal transplantation; however, due to donor limitation, this treatment is non-feasible. Alternatively, applying cyanoacrylate or fibrin glue is the treatment used clinically. Nonetheless, these treatments have been shown to cause inflammation and result in recurrence of the perforation which may lead to a full thickness donor transplantation in future. Thus, an easily available and applicable, biological and non-immunologic solution is required for a better treatment. For this, injection of in situ crosslinked and biocompatible hydrogels can provide a better long-term solution. Even though there are several different strategies for crosslinking of hydrogels such as chemical crosslinking, enzyme mediated, or UV-initiated crosslinking, there are several limitations in these methods such as cytotoxicity or immunogenic potential of the method. This study involves the development of injectable in situ forming gel crosslinked by Fenton´s reaction, a chemical mimic of horseradish peroxidase (HRP), which can have potential applications for corneal perforations. The polymers used in this study were both synthetic polymers such as poly (ethylene glycol) (PEG) and ECM-derived such as gelatin.The results demonstrated that it is possible to tune the mechanical properties and gelling kinetics of the resulting hydrogel by adjusting the reactant compositions. In vitro cytotoxicity tests were performed for relevant concentrations of Fe (II) and hydrogen peroxide, and have shown that the cells remained viable.

No description available.