Neste trabalho, anticorpos anti-IgGh foram conjugados às nanopartículas de prata (NPAg) para detectar imunoglobulina G humana (IgGh). Um imunoensaio colorimétrico baseado na diminuição da agregação devido ao aumento da repulsão eletrostática após a interação ligante-alvo. A agregação é induzida pela variação da força iônica e uma mudança da coloração da suspensão coloidal de amarelo para vermelho pode ser observada. Na presença de IgGh, a agregação é inibida e a coloração da suspensão coloidal não se altera. As nanopartículas foram obtidas por meio de cinco procedimentos diferentes e caracterizadas por espectroscopia UV-Vis, espalhamento dinâmico de luz, difração de raios-X e microscopia eletrônica. Glicose e borohidreto de sódio foram utilizados como agentes redutores, enquanto CTAB e β-ciclodextrina foram utilizados como estabilizantes. Citrato de sódio foi utilizado como agente redutor e/ou estabilizante. Nanoesferas de carbono foram obtidas por tratamento hidrotérmico de uma solução aquosa de glicose e também foram utilizadas no preparo das nanopartículas. As nanopartículas foram funcionalizadas com ácido mercaptossuccínico e a conjugação ocorreu devido à interação entre grupos aminas e grupos carboxílicos ionizados, presentes no anticorpo e agente de acoplamento, respectivamente. A estabilidade dos conjugados e o efeito da adição de IgGh foram avaliados para todos os sistemas preparados. As nanopartículas de prata preparadas com borohidreto de sódio e citrato de sódio foram selecionadas para serem aplicadas no desenvolvimento do imunoensaio e as condições experimentais foram avaliadas. Em condições ótimas, observou-se uma correlação linear entre a diminuição da agregação do sistema (NPAg-anti-IgGh) e a concentração de IgGh (0 a 200 ng mL-1). O limite de detecção foi estimado em 25 ng mL-1. O método colorimétrico apresentou boa seletividade para a detecção de IgGh. Além disso, foi obtido um resultado satisfatório ao aplicar o método para determinação do fator IX de coagulação. Foi desenvolvido também um método para determinação de ATP baseado na agregação de nanopartículas de ouro. Aptâmeros foram utilizados como elemento de reconhecimento. Em princípio, o método pode ser aplicável à determinação de outros analitos, por meio da substituição do aptâmero utilizado neste trabalho pelo oligonucleotídeo específico para o alvo de interesse. / In this work, antibodies to human immunoglobulin G (anti-IgGh) were used in combination with silver nanoparticle (NPAg) to detect IgGh. A colorimetric immunoassay based on the decrease of aggregation due to increased electrostatic repulsion upon ligand-target interaction. Aggregation was induced by varying the ionic strength and the solution of NPAg-anti-IgGh shows obvious visible color change from yellow to red. In the presence of IgGh aggregation the nanoparticle is inhibited and coloration of the colloidal solution does not change. The nanoparticles were obtained using five different procedures and they were characterized by UV-Vis spectroscopy, dynamic light scattering, X-ray diffraction and electron microscopy. Glucose and sodium borohydride were used as reducing agent, as CTAB and β-cyclodextrin reagents were used as stabilizers. Sodium citrate was used as reducing and stabilizing agent. Carbon nanospheres were prepared by hydrothermal treatment of glucose and used in the preparation of NPAg. The nanoparticles were functionalized with dimercaptosuccinic acid and their conjugation occurred due to the interaction of positively charged amine groups and anionic groups (-COO-) present on the antibody and coupling agent. The stability of conjugates and the variation of aggregation in the presence of IgGh were evaluated for all systems. The NPAg prepared by sodium borohydride were selected for use in the immunoassay and the optimum conditions of the assay were investigated. Under the optimal conditions, the ration between the absorbance at 396 nm and 564 nm was linearly proportional to the IgGh concentration on a range from 0 to 200 ng mL-1, with a detection limit of 25 ng mL-1. The colorimetric method showed good selectivity for IgGh detection. It was possible to adapt the method to the determination of other proteins, such as factor IX. In another approach, anti-aptamer ATP was used to develop a colorimetric method for the determination of ATP based on stabilization of gold nanoparticles provided by strands of DNA.The strategy was based on stabilization of nanoparticles due to interaction with single strands of DNA, and the change of the stability of the nanoparticles provided by the conformational change of the aptamer following recognition. This method could in principle be used to detect analytes by substituting the aptamer used in this study by the specific aptamer for the target of interest

In modern research and industrial applications, the importance of coatings can hardly be underestimated. Coatings are used extensively in optics, biomedical instruments, cutting tools, and solar panels to name a few. The primary purpose of any coating is to alter surface properties of the base material thus adding new functionality or improving the performance of the original product. A multitude of coating techniques has evolved over the years with spray coating being one of the more widely used. Some applications require deposition of materials that are either in the form of a solution or suspension. Therefore, before or during the deposition process small droplets of the said liquid are formed and transferred onto the substrate. Since differently sized droplets have different surface impact dynamics, droplet velocity at the impact plays an important role in the way it will adhere to the surface. Most spray coating techniques do not take into account the process of droplet-surface interaction which may result in overspray, poor coating thickness control, and material waste. The research presented in this dissertation outlines the supporting principles, design, fabrication and testing of an innovative spray coating system that provides the ability to fine tune coating parameters, including droplet impact velocities, to provide close to optimum deposition conditions. The core of the design consist of a dual velocity nozzle unit that ensures acceptable range of droplet velocities at the surface, while keeping droplets from accelerating excessively inside the system. Early experiments showed the system’s potential to produce nanoparticle coatings with particles uniformly distributed across the substrate. In addition, pigment coating for improved 3D scanning was also performed, thereby improving the surface definition and accuracy of the scanning results. Scalability of the system also led to experiments in applying this technology to microprinting. Preliminary microprinting results illustrated the system’s flexibility and opened new research avenues in micro-coating, microprinting, and, possibly rapid prototyping. Furthermore, thanks to the highly adaptable nature of the proposed design, seamless incorporation of a torch-like device into the nozzle unit was also possible. That provided the opportunity to perform in situ thermal processing or sintering of deposited material as well as production of a nanoparticle coating in a one-step process by thermally decomposing precursor solution. Technology developed during the research work presented in this dissertation demonstrated its ability to be adapted in a number of applications that can benefit both industry and engineering research alike. Large area coatings, nanoparticle production, micro-coating, and coatings for improved 3D scanning are just a few areas where the presented technique can already, or may, if developed further, outperform existing and widely accepted methods. Fine tuning of the system to a particular application, and tapping into its potential in other fields will be explored in future research. / Graduate

Um dos maiores desafios da Implantodontia é manter a osseointegração e a saúde dos tecidos peri-implantares após a instalação da prótese. Para que uma reabilitação sobre implantes tenha longevidade é necessário que se realize a manutenção da saúde dos tecidos peri-implantares. Existe uma relação direta entre o acúmulo de biofilme e a presença da inflamação desses tecidos, denominada mucosite. Essa condição pode evoluir para uma peri-implantite. A proposta deste estudo foi encontrar uma solução preventiva às doenças peri-implantares, através do controle do biofilme. Avaliou-se a ação antibacteriana de três tipos de revestimentos nanoestruturados com prata aplicados à superfície de discos de titânio frente a cepas de microrganismos peri-implanto-patogênicos. Após determinado o melhor revestimento, analisou-se, também, se a quantidade de prata (3 ou 6 camadas) melhorava sua ação antimicrobiana. Foram confeccionados discos de titânio divididos em 4 grupos: titânio sem deposição (controle), titânio com deposição de solução coloidais de prata e sílica (Si02), titânio com deposição de solução coloidal hidrotermalizada de prata e dióxido de titânio (TiAg) e titânio com deposição de solução hidrotermalizada somente com dióxido de titânio (TiAa). Testou se a efetividade da atividade antimicrobiana dos revestimentos estudados por meio da contagem das colônias bacterianas, encontradas na superfície das placas de ágar sangue. Para permitir uma contagem correta do crescimento das colônias, realizou se diluição seriada e, após incubação a 37°C em anaerobiose, a contagem do número de colônias e, posteriormente, o cálculo das unidades formadoras de colônia (UFC/mL). Após determinação do melhor revestimento, foram desenvolvidos biofilmes monoespécie sobre discos de titânio com 3 e 6 camadas do revestimento SiO2, além dos grupos controle positivo (C.positivo) e negativo (C.negativo), utilizando as cepas Streptococcus gordonii. A atividade microbiana nos biofilmes foi determinada pelo método de XTT. Utilizou-se três discos de cada grupo por teste (triplicata) e realizado a leitura em espectrofotômetro à 450 nm e 492 nm. Os resultados obtidos com cepa de A. actinomycetemcomitans, apresentaram diferença estatística (p<= 0,01) entre o grupo controle (branco) e os grupos teste. Observou-se um maior número de bactérias A.a na superfície branca quando comparado com as superfícies nanoestruturadas com prata, sendo que o grupo SiO2 foi o que apresentou melhor resultado. Notou-se, também, que houve uma maior quantidade da bactéria P.gingivalis na superfície dos discos brancos quando comparado com os grupos com revestimentos nanoestruturados com prata. As bactérias S.aureus e F.nucleatum , porém, não apresentaram redução nos discos com filmes nanoestruturados quando comparados ao disco sem revestimento. Os discos com 6 camadas do revestimento SiO2 apresentaram eficiência semelhante a clorexidina 0,12%, na redução do biofilme da S.gordonii. Conclui-se que os revestimentos nanoestruturados com partículas de prata foram efetivos na redução de UFC/ml das bactérias A. actinomycetemcomitans e P.gingivalis, com o melhor resultado observado com revestimento SiO2. A concentração da prata interferiu positivamente nos resultados com a bactéria S.gordonii. / One of implantology\'s major challenge is to maintain the osseointegration and health of the peri-implant tissues after the installation of the prosthesis. To ensure implant rehabilitation\'s longevity it is necessary to maintain the health of the peri-implant tissues. There is a direct relationship between the accumulation of biofilm and the presence of inflammation of these tissues, called mucositis. This condition can progress to peri-implantitis. The purpose of this study was to find a preventive solution to peri-implant diseases through biofilm control. For this, the antibacterial action against strains of peri-implant-pathogenic of three types of nanostructured coatings with silver applied to the surface of titanium discs microorganisms was evaluated. After determining the best coating, it was also analyzed whether the amount of silver (3 or 6 layers) improved its antimicrobial action. Titanium disks were divided into 4 groups: titanium without deposition (control), titanium with deposition of colloidal solution of silver and silica (SiO2), titanium with deposition of colloidal hydrothermalized solution of silver and titanium dioxide (TiAg) and titanium with deposition of a hydrothermal solution only with titanium dioxide (TiAa). The effectiveness of the coatings was tested by counting the bacterial colonies found on the surface of the blood agar plates. In order to allow a correct colony count, a serial dilution was performed and, after incubation at 37 ° C in anaerobiosis, counting the number of colonies and, later, calculating the colony forming units (CFU / mL). After determination of the best coating, monospecies biofilms were prepared on 3 and 6 layer titanium discs of the SiO2 coating, in addition to the positive control (C.positive) and negative (negative) groups, using Streptococcus gordonii strains. The microbial activity in biofilms was determined by the XTT method. Three disks of each group were used per test (triplicate) and the spectrophotometer read at 450 nm and 492 nm. The results obtained with A. actinomycetemcomitans strain presented a statistical difference (p<=0.01) between the control group (blank) and the test groups. A higher number of A.a bacteria was observed on the blank surface when compared to the nanostructured surfaces with silver, and the SiO2 group showed the best results. It was also noted that there was a greater amount of P.gingivalis bacteria on the surface of the blank discs when compared to the groups with nanostructured coatings with silver. The bacteria S. aureus and F. nucleatum, however, did not present reduction in the discs with nanostructured films when compared to the disc without coating. The 6- layer discs of the SiO2 coating presented similar efficiency to 0.12% chlorhexidine in reducing the S. gordonii biofilm. We concluded that nanostructured coatings with silver particles were effective in reducing CFU/ml of A. actinomycetemcomitans and P.gingivalis bacteria and the best result was observed with SiO2 coating. The concentration of silver interfered positively decreasing S.gordonii bacteria number.

No description available.

No description available.

In this study, we have developed a novel way of generating and exposing biological organisms (both prokaryotic and eukaryotic) to silver nanoparticles (AgNPs) and studying the biochemical changes induced by these particles. We analyzed the various organs of Wistar rats for localization and quantification of these particles using mass spectrometric and molecular biological techniques. Highest levels of AgNP was found in the lung tissue in addition to being present in the liver and kidneys. Analysis of the of the blood plasma from AgNP exposed rats revealed elevated levels of glutathione-disulfide, which is indicative of reactive oxygen species (ROS) generation, which was further validated using ROS specific immunofluorescence staining of liver tissue. Quantification of blood lactate levels of the AgNP exposed rats showed increased lactate levels, which is indicative of anaerobic respiration and may result from AgNP-induced oxidative stress. Further analysis of bone marrow cells from AgNP exposed rats showed a higher number of micronuclei formation in developing erythrocytes and bone marrow cytotoxicity. Finally, analysis of the genes involved in the renin-angiotensin system (RAS) and inflammatory response revealed upregulation in transcript levels of many of these important genes in the liver tissue. Taken together, our study provides an initial road map for the identification of different signaling pathways that are altered by the AgNP exposure and contributes to a comprehensive understanding of the mechanism involved in silver nanoparticle-induced toxicity.

Recent advances in nanotechnology have led to the production of materials with nanoscale dimensions (nm) and properties distinctly different from their bulk (>100 nm) counterparts. With increased use, it is inevitable that nanomaterials will accumulate in the environment and there is concern that the novel properties of nanomaterials could result in detrimental environmental and human health effects. In particular, there has been concern recently regarding the use of silver (Ag) based nanomaterials as antimicrobial agents in consumer and medical products. Current regulations dealing with the discharge of metals into the environment are based on total concentrations with no consideration for the form (e.g., ionic, nanoparticle, colloid) which can largely determine toxicity. Methods for the identification and characterization of nanoparticulates within complex matrices are lacking and the development of robust methods for this purpose are considered a high priority research area. This research focuses on the development and application of a novel method for characterizing Ag manufactured nanoparticles (MNPs) within terrestrial environments, in particular in soil pore water, with applications relevant to other metal MNPs as well. The method was then applied to understand the dynamics and behavior of Ag MNPs in soil and soil amended with sewage sludge biosolids.

Made available in DSpace on 2016-08-17T18:39:44Z (GMT). No. of bitstreams: 1 4583.pdf: 2193987 bytes, checksum: a9b3822b8425223d19c05e613a4895db (MD5) Previous issue date: 2012-05-29 / The biological contamination causes a great depth of concern in the polymers industry, whose materials are used for food packaging. Most of the bacteria are associated to a biofilm; complex microbial ecosystem, well structured; thus, it is essential to search for alternatives which can provide the reduction of biofilm accumulation on the surface. One of the alternatives is the usage of nanomaterial for such control. One example of such material is the silver nanoparticle. The human activities produce a lot of residue which have hard decomposition. Research and production with biodegradable plastic open space to a new market by being driven to ecological awareness. One example of such plastic is Poli (lactic acid) (PLA). The aim of such research was to evaluate the anti-bacterial, biodegradable and inhibitory action in the shaping of biofilms on the modified PLA with silver nanoparticle in concentrations of 0,3, 0,5, 1,0 and 1,5 %. Standard strain Staphylococcus aureus and Escherichia coli were used for the antibacterial activity evaluation, through the Japanese regulation JIS Z 2801:2000. For the biofilm inhibition evaluation, the samples were incubated with biofilm forming strains from S. aureus, E. coli and Pseudomonas aeruginosa in a constant shaking and evaluated in 1, 3 and 7 days. The samples were buried with a humidity air system for observation of natural degradation in organic soil, in favor of its bacterial growing for 328 days. The results show that the silver antibacterial action was around 70% for E. coli and a small inhibition of biofilm was observed on the third day for E. coli and P. aeruginosa. The PLA natural biodegradation was stable for the mass loss as well as he significantly loss of molar mass. The analysis of the compound presented good distribution and bad dispersion, which could have influenced on the antibacterial activity. New process methods for the nanoparticle incorporation must be carried out for better dispersion and availability of PLA silver surface. / A contaminação biológica causa grande preocupação na indústria de polímeros, cujos materiais são usados para embalagens de alimentos. A maior parte das bactérias se encontra associadas a um biofilme; complexo ecossistema microbiano, bem estruturado; sendo assim, é essencial buscar alternativas que proporcionem a redução do acúmulo de biofilme nas superfícies. Uma das alternativas é o uso de nanomateriais para tal controle. Um exemplo deste material é a nanopartícula de prata. As atividades humanas produzem muito resíduos de difícil decomposição. Impulsionada pela consciência ecológica, as pesquisas e produção com plásticos biodegradáveis ganham espaço. Exemplo de tal plástico é o Poli (ácido lático) (PLA). O objetivo desta pesquisa foi avaliar a ação antibacteriana, biodegradante e a inibitória na formação dos biofilmes sobre o PLA modificado com nanopartícula de prata nas concentrações de 0,3, 0,5, 1,0 e 1,5 %. Foram utilizadas cepas padrão de Staphylococcus aureus e Escherichia coli para a avaliação da atividade antibacteriana, através da norma japonesa JIS Z 2801:2000. Para a avaliação da inibição do biofilme as amostras foram incubadas com cepas formadoras de biofilme de S. aureus, E. coli e Pseudomonas aeruginosa em constante agitação e avaliadas em 1, 3 e 7 dias. Para a observação da degradação natural em solo orgânico as amostras foram enterradas com um sistema de ar e umidade, favorável ao crescimento bacteriano por 328 dias. Os resultados mostraram que a ação antibacteriana da prata foi de aproximadamente 70 % para E. coli e uma pequena inibição do biofilme foi observada no terceiro dia para E. coli e P. aeruginosa. A biodegradação natural do PLA foi estável para a perda de massa e foi observada redução significativa de massa molar. A análise do composto apresentou boa distribuição e má dispersão, que pode ter influenciado na atividade antibacteriana. Novos métodos de processamento para a incorporação das nanopartículas devem ser realizados para melhor dispersão e disponibilidade da prata na superfície do PLA.

Ultrafiltration (UF) processes are often used as pretreatment before more retentive/costly processes, such as nanofiltration and reverse osmosis. This study shows the results of low-biofouling nanocomposite membranes, loaded with casein-coated silver nanoparticles (casein-Ag-NPs). Membranes were cast and imbedded with Ag-NPs using two approaches, physical blending of Ag-NPs in the dope solution (PAg-NP/CA membranes) and chemical attachment of Ag-NPs to cast membranes (CAg-NP/CA membranes), to determine their biofouling control properties. The functionalization of Ag-NPs onto the CA membranes was achieved via attachment with functionalized thiol groups with the use of glycidyl methacrylate (GMA) and cysteamine chemistries. The immobilization chemistry successfully prevented leaching of silver nanoparticles during cross-flow studies. Pseudomonas fluorescens Migula in brackish water was used for short-term dead-end filtration, where CA and CAg-NP/CA membranes displayed lower flux declines as compared to PAg-NP/CA membranes. In subsequent long-term biofouling studies, also with Pseudomonas fluorescens Migula in brackish water with addition of sodium acetate, chemically-attached Ag-NPs led to a significant reduction in the accumulation of bacterial cells, likely due to the more dispersed nanoparticles across the surface. Therefore, a method was developed to chemically immobilize Ag-NPs to membranes without losing Ag-NP’s antimicrobial properties.

No description available.