Polymer-Based membranes play a critical role in several industrially important gas separation processes, e.g., carbon dioxide removal from natural gas. However, an intrinsic trade-off between membrane flux (characterized by its permeability) and selectivity to one gas over the other has limited their effectiveness in practical environments. While some incremental success has been obtained by empirically developing new polymer chemistries, the best hopes for transformative improvements may require novel architectures employing predictive structure/property relationships. In this work, we develop a novel hybrid membrane construct comprised of inorganic nanoparticles grafted with polymer chains to form grafted nanoparticles. We find that the grafting architecture almost exclusively results in enhanced gas transport properties, in contrast with those expected from conventional predictions. These enhancements, found to be a result of elevated diffusion constants, are broadly tunable with the grafted chain length and leads to order of magnitude increases in gas permeability. We conjecture that the grafted polymer chains serve to impart added free volume to the composite material, which manifests itself as enhanced gas diffusion relative to the pure polymer. Indeed, multiple experimental and simulation probes verify this picture, and indicate that the free volume increases are a result of the grafted chains adopting anisotropic conformations to fill space. Building off of this finding, we systematically study the effects of the nanoparticle core size and chain grafting density, and find that both the chain length where the maximum permeability occurs, as well as the extent of the enhancement, varies depending on the relative sizes of the chains and the nanoparticle. A thorough structural analysis of the grafted nanoparticles in dilute solution as well as bulk samples indicate that the relation between the measured polymer brush height and the chain length undergoes a transition at intermediate chain lengths, similar to the observed gas permeability enhancements. Using a simple scaling approach, we show that this transition is related to the crossover from a concentrated polymer brush with higher order scaling to a semi-dilute brush where the chains are more ideal. We hypothesize that this impenetrable concentrated brush phase is the source of the added free volume, and that this effect is diminished when the grafted chains are longer than the transition point and the penetrable, semi-dilute polymer brush begins to dominate gas diffusion. When cast in the framework of free volume theories, this prediction accurately captures the trends in gas diffusion; the result is a unique structure/property relation that can be used to design optimal membrane materials. We expand on these constructs to probe other grafted nanoparticle-based architectures incorporating free polymer chains and advanced chemistries to further manipulate the gas transport properties of these mixed-matrix materials. The addition of free chains with judiciously chosen molecular weights and loadings gives a nearly independent means to tune membrane selectivity, which when combined with the intrinsic permeability increases in the matrix-free grafted nanoparticles results in superior materials that can exceed the current performance Upper Bound. We relate this result to the spacial distribution of the free chains throughout the grafted polymer corona, and how this affects the distribution of the free volume in the material as it selectively cuts off larger gas molecules. We further leverage this universal grafting platform by grafting polymer chains with novel chemistries to design membranes with record-setting selectivities while also increasing permeability by nearly two orders of magnitude. We conclude that grafted nanoparticle constructs allow for precise and predictive control of gas transport properties through a new structure/property relation, and serve as a novel material design platform with the potential to function as high performance gas separation technologies.

Aptamers have shown a great potential due to their cheaper synthesis and easy chemical modification compared to antibodies, and have been employed in various biological assays and applications throughout the last two decades. Despite of their limitations, such as non-specific binding and low nuclease resistance, aptamers could be successfully used in the biomarker discovery and for the development of the aptamer-based imaging probes for in vitro assays. In this thesis, luminescent aptamer-conjugated nanoparticles were developed and utilized for leukemia cell detection with fluorescent microscopy. It was shown that for the bioconjugation of an aptamer with luminescent nanoparticles it is more beneficial to use carboxyl-modified nanoparticles, which results in a stable luminescence after the conjugation and the absence of unsaturated and unstable conjugates, unlike with amino-modified nanoparticles. Moreover, a cell viability assay was performed and it was revealed that aptamer-conjugated nanoparticles did not induce spontaneous apoptosis and necrosis of leukemia cells, which can be further explored with additional cytotoxicity tests, whether the aptamer-conjugated nanoparticles are biocompatible, or not. Aptamer-based biomarker discovery implies disease biomarker identification, and most commonly used methods are tedious and require a relatively high concentration of captured aptamer-target complexes. For that, AptaBiD was used in order to optimize aptamer-target identification method. Using Sgc8-aptamer, it was first shown with flow cytometry that it binds to both, healthy and malignant T lymphocytes, which requires further improvements for this aptamer to be used for leukemia detection. Among three tested detergents for the aptamer-target purification, DDM happened to be the most suitable one, due to its gentle cell lysis and solubilization properties. However, the cross-linking with formaldehyde has not positively affected the results obtained and could be replaced with photocross-linking in future experiments, which would allow to selectively cross-link an aptamer with a photomodified nucleobase with its target. Lastly, a high number of intracellular proteins identified within samples could be associated with the aptamer non-specific binding and internalization, which could be improved in future with an alternative cell fractionation with a membrane isolation approach used for the identification of transmembrane target protein.

This thesis focuses on core/shell nanoparticle catalysts including preparation, characterization and testing performance using direct methanol fuel cell. Core/shell were prepared using noble and non-noble metals. Also some core/ shell nanoparticles supported on silica and different types of carbon were prepared as well in this thesis. Non-noble core/shell nanoparticles including novel Co/Ni, SiO2/Ni using three types of silica and novel SiO2/CoFe were prepared by a new modified sol-gel method using hydrazine in alkali media as the reducing agent to reduce metal chloride through two steps process. Parameters such as temperature, pH of solution and reducing agents, were seen to be of great importance in deciding the morphology of the final product as well as the structure of the core/shell catalyst. Core/shell nanoparticles have been successfully prepared for Co/Ni and SiO2/CoFe for first time by choosing the right parameters. This study presents the unique structure which has not been obtained previously for SiO2/Ni catalyst using commercial silica as core. A novel halo shaped structure was the common feature in the catalysts prepared as indicated by TEM. This study presents as well noble Ru/Pt core/shell nanoparticles supported on three types of carbon by a new modified polyol method for first time. The author of this work is not aware of any studies that have prepared Ru/Pt on carbon powder smaller or equal to 50 nm and Ru/Pt on CMWNT previously. This work presents special structure (crown- jewel shaped) for Ru/Pt on Vulcan XC-72 carbon which was not obtained previously for the same catalyst. Selected catalysts were tested using a direct methanol fuel cell. SiO2/Pt core/shell nanoparticles were prepared for the first time by two different methods, namely a new modified sol-gel and polyol methods with novelty structures halo and crown- jewel shaped respectively. Based on the particles size obtained from TEM images, the modified polyol method seems to have a much greater impact on the particles size than the modified sol-gel method. Based on these findings Ru/Pt, Ru/Pt supported on three different types of carbon and Pt supported on CMWNT were prepared using the new modified polyol method. Pt on CMWNT catalyst was synthesized for the first time successfully by a new modified polyol method and all the particles were found to be well dispersed with a narrow size distribution of an average particles size of 3nm. This catalyst gave promising results on DMFC. Pt supported on CMWNT and Ru/Pt supported on Vulcan and CMWNT were used for the first time as electro-catalysts in DMFC to study the effect of the support on the catalytic activity of catalysts. The results show that Ru/Pt on CMWNT gives better performance than the unsupported Ru/Pt and Ru/Pt on Vulcan XC-72. Using Ru/Pt on CMWNT with higher methanol concentration (anode feed) improved the fuel cell power density when compared with the RuPt commercial catalyst.

Wang Juan = 納米金顆粒與氧化鋁複合物薄膜光學吸收譜中的尺寸和濃度效應 / 王娟. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 55-58). / Text in English; abstracts in English and Chinese. / Wang Juan = Na mi jin ke li yu yang hua lv fu he wu bo mo guang xue xi shou pu zhong de chi cun he nong du xiao ying / Wang Juan. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgment --- p.iii / Table of contents --- p.iv / List of Figures --- p.vii / List of Tables --- p.ix / Chapter CHAPTER 1: --- Introduction --- p.1 / Chapter CHAPTER 2: --- Background --- p.3 / Chapter 2.1 --- Optical response of metal-particle/matrix composite system in an electronic field --- p.3 / Chapter 2.1.1 --- The concept of plasmon and the dielectric function of metal particle --- p.3 / Chapter 2.1.2 --- The concept of surface plasmon resonance --- p.4 / Chapter 2.2 --- The theories describing the optical absorption properties of metal particle/matrix composite system --- p.5 / Chapter 2.2.1 --- The Mie theory --- p.5 / Chapter 2.2.2 --- The Maxwell-Garnett (M.G.) effective medium theory --- p.6 / Chapter 2.3 --- Previous experimental works in the field --- p.7 / Chapter CHAPTER 3: --- Experimental and instrumentation --- p.8 / Chapter 3.1 --- Fabrication of the Au-nanoparticle /A12O3-matrix composite thin films --- p.11 / Chapter 3.1.1 --- Sputtering techniques and radio-frequency magnetron sputtering --- p.11 / Chapter 3.1.2 --- Experimental set up and the deposition process --- p.13 / Chapter 3.2 --- The chemical and structural characterizations of the films --- p.14 / Chapter 3.2.1 --- X-ray Photoelectron Spectroscopy (XPS) --- p.14 / Chapter 3.2.2 --- X-ray Diffraction (XRD) --- p.15 / Chapter 3.2.3 --- Transmission Electron Microscopy (TEM) --- p.17 / Chapter 3.3 --- The optical absorption measurement: UV spectrometer --- p.21 / Chapter CHAPTER 4: --- Results and discussions --- p.23 / Chapter 4.1 --- General description of the as-prepared samples --- p.23 / Chapter 4.1.1 --- Chemical composition of the films --- p.23 / Chapter 4.1.2 --- General microstructure of the films and the relationship between the deposition parameters --- p.25 / Chapter 4.2 --- The optical absorption: relationship between the SPR absorption and the microstructure --- p.27 / Chapter 4.2.1 --- The shifting of the surface plasmon resonance --- p.27 / Chapter 4.2.1.1 --- The size effect on the SPR frequency shifting --- p.27 / Chapter 4.2.1.2 --- The concentration effect on the SPR frequency shifting --- p.42 / Chapter 4.2.2 --- The broadening of the surface plasmon resonance: size dependence of the relaxation time of free electrons --- p.51 / Chapter CHAPTER 5: --- Conclusions --- p.53 / Appendix --- p.54 / Reference --- p.55

Chapter 1 briefly introduces the background, problems, applications as well as recent progress of the nanobubbles research. The relationship between the formation/stabilization of nanobubbles and the long-rang structures of water molecules, particularly the restructuring of water molecules at the water/gas interface, are emphasized. / Chapter 2 introduces the theories of static and dynamic light scattering and Zeta-potential measurements as well as the details of the instrument set-up. In this chapter, the fundamental equations of the scattering theory are figured out basis on the quasi-classical electrodynamics and combination of the statistical mechanics as well as molecular dynamic theory. Finally, the statistical properties of photon counting are discussed. / In chapter 3, aqueous solutions of tetrahydrofuran, ethanol, urea and alpha-cyclodextrin were studied by a combination of static and dynamic laser light scattering (LLS). In textbooks, these small organic molecules are soluble in water so that there should be no observable large structures or density fluctuation in either static or dynamic LLS. However, a slow mode has been consistently observed in these aqueous solutions in dynamic LLS. Such a slow mode was previously attributed to some large complexes or supramolecular structures formed between water and these small organic molecules, Our current study reveals that it is actually due to the existence of small bubbles (∼100 nm in diameter) formed inside these solutions. Our direct evidence comes from the fact that it can be removed by repeated filtration and regenerated by air purging. Our results also indicate that the formation of such nanobubbles in small organic molecules aqueous solutions is a universal phenomenon. Such formed nanobubbles are rather stable. The measurement of isothermal compressibility confirms the existence of a low density micro-phase, presumably nanobubbles, in these aqueous solutions. Using a proposed structural model, i.e., each bubble is stabilized by small organic molecules adsorbed at the gas/water interface, we have, for the first time, estimated the pressure inside these nanobubbles. / In chapter 4, by using a combination of laser light scattering (LLS) and zeta-potential measurements, we investigated effects of salt concentration and pH on stability of the nanobubbles in alpha-cyclodextrin (alpha-CD) aqueous solutions. Our LLS results reveal that the nanobubbles are unstable in solutions with a higher ionic strength, just like colloidal particles in an aqueous dispersion, but become more stable in alkaline solutions. The zeta-potential measurement shows that the nanobubbles are negatively charged with an electric double layer, presumably due to the adsorption of negative OTT ions at the gas/water interface. It is this double layer that plays dual roles in the formation of stable nanobubbles in aqueous solutions of water-soluble organic molecules; namely, it not only provides a repulsive force to prevent the inter-bubble aggregation and coalescence, but also reduces the surface tension at the gas/water interface to decreases the internal pressure inside each bubble. / In chapter 5, the addition of salt can induce slow coalescence of nanobubbles (∼100 nm) in an aqueous solution of alpha-cyclodextrin (alpha-CD). A combination of static and dynamic laser light scattering was used to follow the coalescence. Our results reveal that its kinetic and structural properties follow some scaling laws; namely, the average size (<zeta>) of nanobubbles is related to their average mass (<M>) and the coalescence time (t) as <M> <zeta>dr and <zeta> ∼ tgamma with two salt-concentration dependent scaling exponents (df and gamma) For a lower sodium chloride concentration (C NaCl = 40 mM), gamma = 0.13 +/- 0.01 and df = 1.71 +/- 0.02. The increase of CNaCl to 80 mM results in gamma = 0.32 +/- 0.01 and df = 1.99 +/- 0.01. The whole process has two main stages: the aggregation and the coalescence. At the lower C NaCl, the process essentially stops in the aggregation stage with some limited coalescence. At higher CNaCl leads the coalescence after the aggregation and results in large bubbles. / In this thesis, the nanobubbles in the aqueous solutions have been studied by using combination of static and dynamic laser light scattering (LLS), isothermal compressibility measurements and Zeta-potential measurements. We found that the nanobubbles extensively exist in aqueous solutions and the interface of each nanobubble is negatively charged. The addition of electrolytes can destabilize such interface to induce the coalescence of nanobubbles. / Jin, Fan. / "Aug 2007." / Adviser: Chi Wu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1030. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

The materials synthesised in this study were designed to have novel morphology coupled with a tightly controlled surface composition that could be varied depending on a application. Preparations with simple single metal oxides (i.e. TiO2, SiO2, Al2O3 and ZrO2) were used as the starting point with the latter stages involving multi-metal oxide coatings and materials. The research was divided into three interconnected areas; i) biotemplating, ii) alternative synthetic morphologies to biotemplating and iii) the synergy between microparticles and insecticides. For the investigation into biotemplating pollen was chosen as the main example due to its ubiquity. Here, good replication of its structure with metal oxides can be achieved by two-dimensional solgel chemistry. Such materials can be further modified to have tunable surface chemistry through dopants and optical properties (i.e. fluorescence) through the use of dyes. Materials were extensively characterised using primarily spectroscopy (UV and IR) and microscopy (i.e. SEM coupled with EDX elemental analysis). These were considered for several applications and examples investigated here included as a taggant technology and photocatalytic removal of methyl orange in an aqueous environment (TiO2-pollen only). For the latter, results have been compared with those of a commercially available alternative (P25) where the preliminary results are very promising. The method of overcoating was also shown to be transferrable to other flora and fauna biotemplates. Synthetic alternatives for the biotemplated pollen were considered in the second investigative area where solution sol-gel processes such as the Stöber method were considered in addition to other suspension based precipitation methods (i.e. refluxes and microemulsions). Processes developed in the biotemplating research were applied here and analysed again using spectroscopy and microscopy as the main techniques. As part of this aspect, a novel fast-drying water-in-oil microemulsion delivery and preparative system was also developed using low boiling point solvents such as isopentane and ethanol and low toxicity sucrose ester surfactants. Hollow oxide shells could be prepared in these using a novel low-temperature route that were comparable in thickness (but significantly smaller in size) to hollow pollen replicas. In this second area attention was shifted to more focus on oxides of Si and Al (as opposed to TiO2 that used extensively in biotemplating) to broaden the scope of the research and investigate other potential applications, such as nanoabrasives (surface roughness and ability to cleave DNA). The third and final area of interest used the materials from the previous two aspects in coatings that were applied to investigating the knockdown (KD) and total mortality (TM) of selected arthropods. Here mosquitoes of the A. Gambiae and S. Aegypti genus were considered with particular focus on synergistic effects with existing commercial insecticides (using mainly CDC bottle tests). Microscopy was used as the primary characterisation technique here to determine particle transfer after each assay. In these tests %TM suggested SiO2 microspheres were particularly effective at in enhancing mortality of the commercial l-cyhalothrin insecticide. Additionally, novel methods of recording mosquito behaviour was investigated through optical and thermographic stills and videos.

Orientador: Patricia Petromilli Nordi Sasso Garcia / Co-orientador: Alessandra Nara Souza Rastelli / Banca: Juliana Alves Bonini Duarte Campos / Banca: Patricia Aleixo dos Santos / Resumo:Resumo: Avaliou-se a atividade antibacteriana de diferentes concentrações de nanopartículas de óxido de zinco incorporadas a um cimento de ionômero de vidro (CIV) quimicamente ativado e outro modificado por resina fotopolimerizável sobre o biofilme de Streptococcus mutans em diferentes tempos de maturação. As concentrações de nanopartícula foram 0%, 1% e 2%, os CIVs utilizados foram o Fuji II (GC América) e Fuji II LC (GC América) e os tempos de maturação foram 24 horas e 7 dias. Confeccionou-se corpos de prova (N=108) circulares (4mm x 2mm). A atividade antibacteriana foi avaliada pela contagem das Unidades Formadoras de Colônia por Mililitro (UFC/ml). Analisou-se a morfologia celular em Microscopia Eletrônica de Varredura (MEV). Os dados obtidos para cada material atenderam os pressupostos de normalidade e homocedasticidade. Procedeu-se a Análise de Variância a dois fatores (tempo de maturação do biofilme e concentração de nanopartículas) ( =5%). Para o CIV quimicamente ativado encontrou-se diferença não significativa na atividade antibacteriana segundo o tempo de maturação do biofilme (p=0,744), concentração de nanopartículas (p=0,966) e a interação entre eles (p=0,800). Para o CIV modificado por resina, observou-se que a média de UFC/ml do biofilme com 7 dias foi significativamente superior à do biofilme de 24 horas (p=0,034). A concentração de nanopartículas (p=0,570) e a interação entre os dois fatores (p=0,756) não foi significativa. Na análise em MEV não foi observada mudança na morfologia celular do Streptococcus mutans. Conclui-se que a inclusão de nanopartículas de óxido de zinco à 1% e 2% aos CIVs avaliados não alterou sua atividade antibacteriana. / Abstract: Abstract: This study evaluated the antibacterial activity of different concentrations of zinc oxide nanoparticles incorporated into a self-cured glass ionomer cement (GIC) and a light-cured resin-reinforced glass ionomer cement on Streptococcus mutans biofilm at different maturation times. Nanoparticles concentrations were 0%, 1% e 2%, the GICs were Fuji II (GC America) and Fuji II LC (GC America) and the maturation times were 24 hours and 7 days. Were prepared circular (4mm x 2mm) specimens (N= 108). The antibacterial activity was evaluated by the number of Colony Forming Unit per militers (CFU/ml). Morphological analysis of biofilm was taken by scanning electron microscopy (SEM). The data obtained for each material attended the assumptions of normality and homoscedasticity and a two-way ANOVA ( =5%). No significant difference was observed according to the time of biofilm maturation (p=0.744), concentration of nanoparticles (p=0.966) and their interaction (p=0.800). Resin-reinforced GIC showed significantly higher CFU/ml mean for 7-day biofilms compared to 24h-biofilms (p=0.034). The concentration of nanoparticles (p=0.570) and the interaction (p=0.756) between the two factors was not significant. SEM analysis showed no change in cell morphology of S. mutans according to the type of GIC, maturation time and nanoparticles concentration. We conclude that the inclusion of zinc oxide nanoparticles at concentrations of 1% and 2% into the glass ionomer cement evaluated did not promote antimicrobial activity against Streptococcus mutans. / Mestre

En ingénierie tissulaire, la survie in vivo de cellules souches implantées au sein d’un biomatériau est limitée par les conditions d’un environnement ischémique qui se caractérise par un déficit en oxygène et en nutriments. Récemment, dans le cadre d’un projet de recherche dédié au développement d’un hydrogel composite à base de fibrine, biomatériau conçu pour améliorer la survie de cellules souches post-implantation, il a été mis en évidence la nécessité de contrôler dans le temps et l’espace la disponibilité du glucose au sein de ce matériau. Cet apport in situ de glucose est réalisé par dégradation contrôlée de l’amidon, un polymère de glucose. Cette production est assurée par action enzymatique d’un catalyseur spécifique de l’hydrolyse de l’amidon, l’amyloglucosidase (AMG).Toutefois, il convient de maitriser différents paramètres tels que la fuite de l’AMG en dehors de l’hydrogel ou encore sa perte d’activité au cours du temps. Dans ce contexte, l’encapsulation de l’AMG dans des nanoparticules d’un polymère biodégradable et biocompatible, ici l’acide poly(lactique-co-glycolique) (PLGA), devrait permettre le contrôle des paramètres susmentionnés.Des nanoparticules de type core-shell contenant l’AMG (NPe) ont été synthétisés par l’adaptation d’un protocole de double émulsion (water-oil-water). Différentes méthodes ont été développées pour déterminer les propriétés physico-chimiques et biochimiques des nanoparticules produites. Le protocole de synthèse a été optimisé afin de produire des nanoparticules reproductibles et stériles utilisables dans des hydrogels implantables in vivo.Le cahier des charges de l’hydrogel enrichi en amidon et en NPe impose un apport continu du glucose pendant 1 mois. La stabilité des nanoparticules a été étudiée en solution et dans les hydrogels. La production de glucose grâce à ces NPe a été investiguée en solution et en hydrogel mettant en avant l’intérêt de ces nanoparticules au sein du dispositif. / In tissue engineering, the in vivo survival of stem cells located within a biomaterial is limited by an ischemic environment characterized by a low supply of oxygen and nutrients. Recent studies on fibrin based hydrogels (designed to improve stem cells survival after implantation) have highlighted the need to control the spatiotemporal availability of glucose within a biomaterial scaffold. Glucose release occurs through the degradation of starch, a glucose polymer, at a rate controlled by the action of the enzyme amyloglucosidase (AMG), a specific catalyst for the hydrolysis of starch.In order to eventually be of clinical impact, critical parameters must be tuned, such as the AMG leakage outside the hydrogel and its loss of activity over time. In this context, AMG encapsulation within nanoparticles of a biodegradable and biocompatible polymer, here poly(lactic-co-glycolic acid) (PLGA), is a promising means toward controlling the above parameters.The AMG-containing core-shell type nanoparticles (NPe) were synthesized by an adaptation of the double emulsion technique (water-oil-water). Different methods have been developed to determine the physicochemical and biochemical properties of the resulting nanoparticles. The synthesis was optimized to produce sterile and reproducible nanoparticles appropriate for in vivo implantable hydrogels.Nanoparticle stability and glucose release were investigated in solution and in hydrogels. A key specification of the hydrogel system, enriched in starch and NPe, is the continuous supply of glucose over 1 month. Glucose production was observed to meet this specification, highlighting the potential advantages of this approach.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Polysaccharide nanoparticles obtained from Anadenanthera macrocarpa tree exudates (angico gum, AG) and chitosan (CH) were produced by polyelectrolyte complex formation as well as by graft polymerization of acrylic acid onto a AG backbone. The polyelectrolyte complexes (PECs) were obtained by using AG and its carboxymethylated derivatives with degrees of substitution 0.20 and 0.63 as polianions. Reaction parameters investigated were polymer concentration, molar mass, order of solution addition, charge ratio (n+/n-) and AG degree of substitution of carboxymethylated samples. Data revealed that nanoparticles formed by adding AG to CH (AGCH) are in the range of 17.4 to 41.9 nm. Increasing polyelectrolyte concentration led to a decrease in particle size. Larger sizes were observed for charge ratios (n+/n-) > 1. Regarding the molar mass effect, the higher the chitosan molar mass, the larger are the particle sizes. Atomic Force Spectroscopy revealed that for samples with charge ratio n+/n- = 1, particle sizes were 10 and 14 nm, for high (CHa) and low (CHb) chitosan molar mass, respectively. These figures are lower than those analyzed by light scattering measurements (25.1 and 28.2 nm respectively for AGCHa at n+/n- = 1). Nanoparticles prepared using carboxymethylated AG (CMA) have their sizes strongly dependent on charge ratio; for those samples obtained from CMA with degree of substitution (DS) 0.20 and CHa, size distribution is similar to that of AGCHa samples. For samples synthesized with 0.63 DS, size distribution is dependent on charge ratio: for n+/n-< 0.8 similar distribution is observed as those of AGCHa and CMCHa; for n+/n- > 0.8 larger particles (140 - 636 nm) are produced. CMACHa with 0.63 DS, n+/n- = 4, was used as a matrix for chloroquine encapsulation resulting in a efficiency of encapsulation of 43 %. In vitro release was investigated at pH 5.8 and 7.4, a slower release profile being observed at pH 5.8, whereby only 20 % of drug was released in 22 days. Faster release was observed at pH 7.4, where 84 % of drug was released in 6 h, completion being achieved only after 10 days. Data obtained seem to point out that this system can be used for oral drug administration. AG nanoparticles were also produced by acrylic acid radical polymerization on AG backbone, using cerium ammonium nitrate (CAN) as initiator and methylene bisacrylamide as crosslinking agent. It was investigated the effects of glycosidic unit/acrylic acid (GU/AA) and AA/CAN molar ratios on particle size. AG/AA nanoparticles were found to have sizes in the range 6.4 â 19.4 nm, according to GU/AA ratio and an average reaction yield of 56.6 %. Decreasing initiator concentration resulted in low particle size and high polidispersity. By inserting AA onto AG backbone, smaller particle size was obtained than homopolymer one (417 nm). No pH response was found for AG/AA nanoparticles. Bovine serum albumin (BSA) was doped in AG/AA nanoparticles, with an encapsulation efficiency of 50 % resulting in a low release profile, where 69 % of BSA being released in 30 days. / NanopartÃculas do polissacarÃdeo extraÃdo de exsudatos de Ãrvores da Anadenanthera macrocarpa (goma do angico, GA) foram produzidas utilizando como rotas de sÃnteses a complexaÃÃo polieletrolÃtica (CEP) com quitosana (QT) e a copolimerizaÃÃo por enxertia de Ãcido acrÃlico (AA). Na rota de complexaÃÃo polieletrolÃtica a goma do angico (GA) e seus derivados carboximetilados (CMA) com grau de substituiÃÃo (GS) de 0,20 e 0,63 foram utilizados como poliÃnions. Foram investigados alguns parÃmetros que influenciam o tamanho da nanopartÃcula tais como: concentraÃÃo dos polissacarÃdeos, ordem de adiÃÃo das soluÃÃes polieletrolÃticas, massa molar da quitosana, razÃo de carga dos polieletrÃlitos e grau de substituiÃÃo da goma do angico carboximetilada. NanopartÃculas formadas pela adiÃÃo de GA a quitosana de alta massa molar (QTa) (GAQTA) possuem valores de tamanho variando de 17,4 a 41,9 nm. O aumento da concentraÃÃo dos polieletrÃlitos ocasionou uma diminuiÃÃo nos tamanhos de partÃculas. Maiores valores de tamanho foram observados para nanopartÃculas com razÃo molar de cargas (n+/n-) > 1. Quanto maior a massa molar da quitosana maior o tamanho das nanopartÃculas. A variaÃÃo do tamanho com ordem de adiÃÃo dos polieletrÃlitos depende de outros fatores como razÃo molar de cargas e massa molar da quitosana. A anÃlise por microscopia de forÃa atÃmica das nanopartÃculas de GAQTa e GAQTb na razÃo de carga n+/n- = 1 apresentam partÃculas ovaladas com diÃmetros de 10 a 14 nm respectivamente. Estes valores sÃo inferiores ao obtidos por espalhamento de luz (25,1 e 28,2 nm respectivamente para GAQTa e GAQTb na razÃo de carga n+/n- = 1). O aumento da densidade de carga pela reaÃÃo de carboximetilaÃÃo afeta significantemente o tamanho das partÃculas. NanopartÃcula formadas com CMA GS 0,20 e quitosana de alta massa molar (QTA) apresenta valores similares ao observado para nanopartÃculas de GAQTa (14 a 30 nm). Quando o GS à aumentado para 0,63 as nanopartÃculas exibem comportamento diferente dependendo da razÃo de carga (n+/n-) na qual a nanopartÃculas foi sintetizada. Para valores de n+/n- < 0,8 os tamanhos de partÃculas sÃo similares aos observados para GAQTa e CMA0,20QTa, entretanto para n+/n- > 0,8 partÃculas maiores sÃo produzidas (~ 140 a 636 nm). O estudo de incorporaÃÃo e ensaio in vitro de liberaÃÃo de cloroquina foi realizado utilizando como matriz nanopartÃculas de CMA0,63QTa na razÃo n+/n- igual a 4 (431 nm) devido a esta apresentar maior eficiÃncia de encapsulamento do fÃrmaco. A nanopartÃcula incorporou 43 % de cloroquina. Em pH 5,8 a liberaÃÃo de cloroquina foi lenta, liberando apenas 20 % em 22 dias. Em pH 7,4 foi observado que a liberaÃÃo à mais rÃpida do que em pH 5,8 tendo liberado 84 % em 6 h, contudo a liberaÃÃo sà atinge o equilÃbrio em 10 dias. Analisando o tamanho de partÃcula e o comportamento da liberaÃÃo, observa-se que este sistema à promissor para administraÃÃo via oral deste fÃrmaco. A segunda rota de sÃntese foi via copolimerizaÃÃo radicalar por enxertia de Ãcido acrÃlico. A reaÃÃo foi realizada utilizando nitrato de amÃnio cÃrico (CAN) como iniciador e bis-acrilamida (MBA) como agente reticulante. Foram avaliados os efeitos da razÃo molar de unidade glicosÃdica/Ãcido acrÃlico (UG/AA) e AA/CAN no tamanho de partÃcula. As nanopartÃculas de goma do angico e Ãcido acrÃlico tiveram tamanhos variando de 6,4 a 19,4 nm dependendo da razÃo UG/AA e um rendimento mÃdio de 56,6 %.Diminuindo a quantidade de iniciador observa-se que o diÃmetro diminui, entretanto que a polidispersividade aumenta. NanopartÃculas sà com poli(Ãcido acrÃlico) apresentam tamanho superior aos valores observados em presenÃa de goma do angico (417 nm). Apesar da presenÃa de Ãcido acrÃlico as nanopartÃculas de GA/AA o tamanho da nanopartÃcula nÃo à sensÃvel ao pH do meio. A incorporaÃÃo de BSA em nanopartÃculas de GA/AA foi de 50 % sendo a liberaÃÃo da proteÃna bem lenta, tendo liberado apenas 69 % da BSA em 30 dias.

Sob o olhar nanotecnológico, a dimensionalidade passa a ser um fator preponderante nas propriedades dos materiais. O ouro metálico com dimensões reduzidas para a escala nanométrica passa a exibir um comportamento peculiar em termos de sua estrutura eletrônica e reatividade. No trabalho realizado busca-se um melhor entendimento das propriedades das nanopartículas de ouro através de um abordagem química, com foco nas interações superficiais e suas correlações com fenômenos de agregação. No campo mais fundamental, foram realizados estudos visando entender a influência de ligantes de diferentes comprimentos de cadeia nos processos de agregação e de fusão de nanopartículas, utilizando-se para tal ligantes de interesse para a química supramolecular: pirazina, 4,4\'-bipiridina, 1,2-bis (4-piridil)etano e 1,4-bis[(4-piridil)etenil]benzeno. Além disso, foram realizados estudos que permitiram a obtenção de nanopartículas de ouro passivadas com o complexo [Fe(CN)5(4-pySH)]3-,gerando um bloco de contrução interessante para a geração de materiais nanoestruturados a partir de ligações do tipo azul da Prússia. Por fim, estudos da interação de nanopartículas de ouro como o suporte inorgânico hidrotalcita foram realizados, possibilitando a geração de um material colorido composto de nanopartículas de ouro suportadas na superfície da matriz inorgânica. O material exibe ainda efeitos de mudança de coloração com o aumento da temperatura, correlacionados com o estado de agregação das nanopartículas metálicas. / Under the nanotechnological point of view, the dimensionality comes into play when one is dealing with many properties from the materials. Bulk gold with dimensions reduced to the nanometric scale shows singular reactivity and electronic properties. In the present work a further knowledge of the gold nanoparticles properties is sought from a chemical approach, through the investigation of surface interactions and their correlations with aggregation phenomena. Studies aiming a further understanding on the influence of different length ligands in the aggregation and fusional processes were performed with the ligands: pyrazine, 4,4\'-bipyridine, 1,2-bis(4-pyridyl)ethane and 1,4-bis[(4- pyridyl)ethenyl]benzene. Furthermore, the investigation of nanoparticles surface interaction with the ligands 2 and 4-mercaptopyridine and their complexes with pentacianoferrate was also investigated allowing the obtainment of building block potentially useful for the generation of nanostructured materials through Prussian blue-like bonds. Finally, the obtainment of a new material based on surface interactions of gold nanoparticles on the inorganic support hydrotalcite was possible. The material exhibits peculiar thermochromic properties with colors dependent on the aggregation state of the nanoparticles.