Hidrogéis compreendem uma importante classe de materiais poliméricos adequados à aplicação como curativos de feridas e queimaduras. A estrutura tridimensional hidrofílica dos hidrogéis permite que estes mantenham a umidade ideal no leito das feridas, absorvam o exsudato e não causem danos ao novo tecido durante as trocas dos curativos. No caso dos hidrogéis, essas trocas podem ser menos frequentes. Além disso, curativos que auxiliem na remoção de tecidos necrosados e ainda sejam capazes de oferecer tratamentos extras que acelerem o processo de cicatrização são desejáveis. Este trabalho apresenta a produção de materiais à base de hidrogel capazes de auxiliar neste processo de diferentes maneiras. Primeiramente, são apresentados hidrogéis formados a partir de nanofibras de poli(N-vinil-2-pirrolidona) (PVP) produzidas por eletrofiação, seguido da reticulação através da utilização de radiação UV-C ou reação de Fenton. A utilização da eletrofiação como técnica auxiliar na formação dos hidrogéis permitiu o controle da porosidade através da formação de fibras de diferentes diâmetros. A evidência de tal propriedade foi constatada através da produção de materiais que apresentam diferentes perfis de liberação da proteína modelo albumina de soro bovino (BSA). O hidrogel de PVP nanoestruturado foi capaz de liberar e manter a atividade da colagenase, uma importante enzima aplicada no tratamento de feridas via desbridamento enzimático, durante as 48 horas em que foi avaliado. Além disso, hidrogéis bactericidas nanoestruturados foram produzidos a partir de nanocompósitos de PVP e nanopartículas de prata (AgNP) produzidos por eletrofiação. Esses hidrogéis apresentaram propriedades térmicas semelhantes aos hidrogéis sem AgNP, diminuindo, contudo, a sua capacidade de intumescimento. Esses hidrogéis mostraram-se ativos contra bactérias gram-positivas e gram-negativas a partir de 100 ppm de AgNPs. Adicionalmente, foi estudada a formação de um hidrogel modelo composto PVP/AgNP/Imidazol, almejando-se a produção de um material bactericida-fungicida a base de hidrogel. Este hidrogel apresentou atividade conta três espécies de Candida a partir de 500 ppm de imidazol no material. Embora exista a formação de um complexo estável entre AgNP e Imidazol, cálculos teóricos e a constatação da atividade fungicida corroboram com o fato de que derivados imidazólicos podem ser liberados a partir deste hidrogel híbrido. A produção de hidrogéis físicos compostos por blendas de PVP/Polianidridos sintetizados a partir de derivados de hidroxicinamatos e ácido salicílico, capazes de liberar moléculas de interesse biológico quando parcialmente degradados hidroliticamente, também é descrita neste trabalho. Os resultados indicam que interações hidrofóbicas entre a PVP e os polianidridos sintetizados podem ser responsáveis pela formação dos hidrogéis físicos e pela miscibilidade das blendas produzidas. Os hidrogéis físicos de PVP/Polianidridos foram obtidos na forma de filmes por evaporação do solvente. Micro- e nanofibras também foram obtidas por eletrofiação. Desta maneira, o presente trabalho contribui com o desenvolvimento de uma geração de curativos multifuncionais aplicados no tratamento de feridas crônicas e queimaduras. / Hydrogels comprise an important class of polymeric materials that finds application as wound and burn dressings. The hydrophilic three-dimensional structure of hydrogels helps to provide the ideal humidity at the wound bed, to remove exsudates and to prevent damages to the new tissue during dressing substitution. Furthermore, these wound dressings are able to remove necrotic tissues and, therefore, capable to offer extra treatments that would benefit the healing processes. This work describes the production of hydrogel based materials that are able to act in wound healing by different ways. First, it is presented hydrogels composed of poly(N-vinyl-2-pyrrolidone) (PVP) nanofibers produced by electrospinning, followed by its crosslinking using UV-C radiation or Fenton reaction. The use of electrospinning in the hydrogel formation allowed porosity control by obtaining fibers of different diameters. This was evidenced by achieving materials that present different release profiles of the model protein bovine serum albumin (BSA). The nanostructured PVP hydrogel was capable of releasing and maintaining collagenase activity during 48 hour of evaluation. This is an important enzyme that find application in wound healing based on enzymatic debridement. Moreover, nanostructured bactericidal hydrogels were produced from PVP and silver nanoparticles (AgNP) composite through electrospinning, resulting in hydrogels with thermal properties similar to those hydrogels without AgNP, decreasing its swelling ability. These hydrogels were active against gram-positives and gram-negatives bacteria starting from 100 ppm of AgNP. In addition, the production of a model hydrogel composed by PVP/AgNP/Imidazole was investigated, aiming at a bactericidal-fungicidal hydrogel based material. This hydrogel was active against three Candida having 500 ppm of imidazole into the structure. In spite of the formation of a stable complex between AgNP and imidazole, theoretic calculations and the observed fungicidal activity corroborate with the fact that imidazoles derivatives can be released from this hybrid hydrogel. Physical hydrogels composed of PVP/Polyanhydrides blends were synthesized from hydroxycinammates derivatives and salicylic acid. These materials which were capable of releasing molecules with biological potential upon hydrolysis, are also described in this work. The results indicate that hydrophobic interactions between PVP and the synthesized polyanhydrides could be responsible for the hydrogel formation and blend miscibility as well. PVP/Polyanhydride physical hydrogels were obtained from cast films. Micro- and nanofibers were also obtained by electrospinning. Thus, the present work contributes with the development of the new generation of smart dressings for wound and burn healing.

As nanopartículas de ouro (AuNPs), com formatos e distribuição de tamanhos definidos, têm atraído grande atenção devido às suas propriedades óticas e e catalíticas únicas, que dependem de da forma e tamanho de AuNPs e que são importantes para diversos aplicações. O desenvolvimento de métodos simples e ecológicamente seguros para a síntese de AuNPs de tamanho e forma controlados, empregando reagentes de baixo custo e de fácil manuseamento é, portanto, de grande importância. Considerando isto, realizou-se um estudo sistemático para preparar nanoparticlus de ouro (AuNPs) e prata (AgNPs) com um controle de forma e tamanho, empregando exclusivamente glicerol como um agente redutor flexivel, eco-friendly e de baixo custo. Em primeiro lugar, descrevemos um novo one-pot método para a preparação de nanorods ou nanobastões de ouro (AuNRs) monocristalinos com quase 100% de rendimento empragando o glicerol em meio alcalino como agente redutor e Brometo de hexadeciltrimetilamónio (CTAB) como agente controlador da forma de particulas. Podemos conseguir um controle da razões de aspecto (Aspect ratio do inglês, AR = 2 a 6), rendimento de AuNRs (27-99%) bem como da posicao de banda de absorção óticas de AuNRs (de 620 a 1200 nm) simplesmente variando as condições experimentais, principalmente o pH de meio reaccional (variou-se entre 12-13,5) e a concentração do AgNO3. Descobrimos que a formação de AuNRs é mais rápida a pH mais alto (> 11) e a maior temperatura (> 30 ° C), mas o rendimento de AuNRs é menor (< 70%). A análise de HRTEM mostrou que os AuNRs crescem na direcção [001] e têm uma estrutura do tipo fcc monocristalina, isenta de falhas estruturais ou deslocamentos. Em segundo lugar, realizamos com sucesso, pela primeira vez, a formação de nanoparticlulas esféricas de ouro (AuNPs), quase monodispersas de cerca de 8 nm, utilizando o glicerol bruto conhecido localmente como Glicerina Loíra (crude glycerol (CG) do inglê), tal como recebido, da planta de biodiesel pela. Não foi realizado nehum tratamento químico ou físico específico do CG, exceto filtração simples. Utilizaram-se duas amostras diferentes de CG com diferentes teores de glicerol (65% e 73%) e diferentes níveis de impurezas (baixo e alto) e tipos (orgânicos e inorgânicos) para preparar AuNPs, a fim de estudar o efeito de possíveis impurezas na formato e distribuição de tamanho de AuNPs. Para comparação, foram também preparadas AuNPs utilizando glicerol comercial puro (99,5%) em condições experimentais idênticas. Foram obtidos AuNPs com tamanho e formato semelhantes em ambos os casos (glicerol puro comercial e CG) indicando que o glicerol comercial pode ser substituído por CG na síntese de AuNPs e as impurezas orgânicas e inorgânicas não afectam significativamente a distribuição de tamanho de AuNPs preparadas . Este estudo abre novas possibilidades para um eco-friendly preparação de nanopartículas metálicas utilizando o CG com um agente redutor barato, não tóxico e biodegradável como. Em terceiro lugar, desenvolvemos um método de síntese de AuNPs do tipo Ligand-free (sem uso de agente establizante) empregando o glicerol tanto como agente redutor quanto com agente estabilizador. A ideia era evitar o uso de um agente estabilizante externo que muitas vezes diminui a actividade catalítica ou afeta adversamente a biocompatibilidade dos sistemas surfactante/AuNPs. Obtiveram-se AuNPs coloidais estáveis com uma distribuição de tamanho razoavelmente estreita (8 &plusmn; 3 nm) por este método e verificou-se que a estabilidade e distribuição de tamanho das partículas dependiam da razão água/glicerol, temperatura e pH dos meios reaccionais. Tais ligand-free AuNPs preparados utilizando glicerol podem ser utilizadas nas aplicações catáliticas e biomédicas. / Gold nanoparticles (AuNPs) especially with a control of size and shape have attracted great attention due to their shape-dependent optical properties that are important for many applications. The development of simpler and greener methods for the synthesis of size- and shape-controlled AuNPs employing low-cost and easily handled reagents is thus of great importance. Thus we have carried out a systematic study to prepare shape- and size-controlled AuNPs and AgNPs employing exclusively glycerol as an eco-friendly, low cost and pH-tunable reducing agent. Firstly, we report a new one-pot seedless method for the preparation of single-crystalline AuNRs in almost 100% yield based on the use of glycerol in alkaline medium as the reducing agent and hexadecyltrimethylammonium bromide (CTAB) as the shape-controlling agent. We could achieve a control of the aspect ratio (AR= 2 to 6), AuNRs yield (27-99%) as well the LSPR band of the AuNRs (620 to 1200 nm) by simply varying the experimental conditions, principally the pH of the reaction media (varied between 12-13.5 ) and the concentration of the AgNO3. We found that the formation of AuNRs is faster at higher pH (>11) and higher temperature (>30°C) but the AuNRs yield is smaller (< 70%). HRTEM analysis showed that the AuNRs grow in [001] direction and have a perfect single crystalline fcc structure, free from structural faults or dislocations. Secondly, we successfully carried out the formation of nearly monodisperse spherical AuNPs of around 8 nm using the as-received crude glycerol (CG) from the biodiesel plant for the first time. No special chemical or physical treatment of CG except simple filtration was carried out. Two different crude glycerol samples with different glycerol contents (65% and 73%) and different impurity levels (low and high) and types (organic and inorganic) were employed to prepare AuNPs so as to study the effect of possible impurities on the shape and size distribution of AuNPs. For comparison, AuNPs were also prepared using pure commercial (99.5 %) glycerol under identical experimental conditions. AuNPs with similar size and shape were obtained in both cases (commercial pure glycerol as well as CG) indicating that commercial glycerol can be replaced with CG in the AuNPs synthesis and the organic and inorganic impurities do not significantly affect the particle size distribution of prepared AuNPs. This study opens up new possibilities for the environment-friendly preparation of metallic nanoparticles using the low-cost, non-toxic and biodegradable CG as a reducing agent. Thirdly, we developed a ligand-free one-pot synthesis method of AuNPs employing the eco-friendly glycerol both as reducing agent and stabilizing agent. The idea was to avoid the use of an external stabilizing agent which often hinder the catalytic activity and adversely affect the biocompatibility of the surfactant/AuNP systems. Stable AuNPs with reasonably good size distribution (8 &plusmn; 3 nm) were obtained by this method and the stability and size distribution of the particles was found to be dependent on the water/glycerol ratio, temperature and pH of the reaction media. Such surfactant-free biocompatible AuNPs prepared using the eco-friendly glycerol may find useful applications in catalysis and biomedical applications.

I. Combined cloud point extraction and Tween 20-stabilized gold nanoparticles for colorimetric assay of silver nanoparticles in environmental water This study investigated a simple, sensitive and selective method for the colorimetric assay of silver nanoparticles (AgNPs) using Triton X-114-based cloud point extraction (CPE) as a preconcentration step and Tween 20-stabilized gold nanoparticles (Tween-AuNPs) as a colorimetric probe. After heating beyond the cloud point temperature of Triton X-114, a solution containing Triton X-114 micelles and AgNPs separated into a surfactant-rich phase (small volume) and a dilute aqueous phase. AgNPs partitioned into a Triton X-114-rich phase through a hydrophobic interaction between Triton X-114 micelles and AgNPs. After phase separation, the concentrated AgNPs oxidized to form Ag+ upon adding H2O2. The generated Ag+ triggered the aggregation of Tween 20-AuNPs in a high-ionic-strength solution because the reduction of Ag+ on the AuNP surface enabled Tween 20 (stabilizer) to be removed from the NP surface. The efficiency of Triton X-114-based CPE of the AgNPs was found to be iv insensitive to their size and coating type. Under optimal extraction and detection conditions, the selectivity of this method for AgNPs was considerably higher than for other nanomaterials. The minimum detectable concentrations for 7, 22, and 54 nm AgNPs were measured to be 0.1, 420, and 600 ng/mL, respectively. This method was successfully applied to the analysis of 7 nm AgNPs in drinking water, tap water and seawater. Keyword: silver nanoparticles, gold nanoparticles, cloud point extraction, Tween-20, colorimetric assay II. Functionalized silver nanoparticles as an extracting and preconcentrating agent for detection of mercury ions In this research we provided highly sensitive and selective for fluorescence assay of combined polythymine oligonucleotide (PolyT) with silver nanoparticles (AgNPs) as an extracting agent to detect mercury ion in environmental water. According to previous researches, PolyT will form a hairpin structure in the presence of Hg2+, this structure provide several 3-D grooves that the fluorescent dye can inlay with it. SYBR Green I (SG) is a staining dye for DNA, when binding with single strand DNA, it shows low fluorescence. On the contrast, SG inlay with grooves of hairpin structure, it shows v 11-fold of fluorescence signal. Hence, we used SG as a fluorescence probe for Hg2+. We modified thiol group at the 5¡¦ of PolyT DNA, because of forming silver sulfur bond, PolyT will able to modified on the surface of AgNPs. PolyT33SH-AgNPs are the extracting and concentrating agent in Hg2+ solution, by the centrifugation, we collected the PolyT33SH-AgNPs. For the purpose of releasing PolyT from AgNPs¡¦ surface, we adding H2O2 to oxidize the AgNPs into Ag+. By mixing buffer and SG into previous solution, mercury ion could be detected. In this study, we successfully detecting Hg2+ in the aqueous solution contained drinking water and tap water. The detection limit in drinking water is 20 pM, which is below Environmental Protection Agency limit for Hg2+ in drinkable water (10 nM), the linear range is from 50-600 pM. On the other hand, the detection limit in tap water is 50 pM, linear range is from 100-700 pM. Keyword: silver nanoparticles, mercury ion, PolyT, SYBR Green I, thymine

Στην παρούσα διπλωματική εργασία γίνεται χρήση τριών διαφορετικών ειδών λεπτών υμενίων διοξειδίου του τιτανίου (TiO2) ως στερεό υπόστρωμα για την ακινητοποίηση πρωτεϊνών με σκοπό την ανάπτυξη και σύγκριση αμπερομετρικών βιοαισθητήρων με ευαισθησία στο υπεροξείδιο του υδρογόνου (H2O2). Το πρώτο είδος των λεπτών υμενίων TiO2 είναι από την εμπορική πάστα της Dyesol η οποία παρασκευάζεται με τη μέθοδο sol-gel, το δεύτερο είδος είναι από μία πάστα δικής μας παραγωγής με τη μέθοδο sol-gel και το τρίτο είδος είναι από μία πάστα που παρασκευάσαμε χρησιμοποιώντας την έτοιμη νανοδομημένη σκόνη TiO2, Degussa P – 25. Τα υμένια TiO2 που έχουν παρασκευαστεί από την εμπορική πάστα της Dyesol χρησιμοποιήθηκαν και για τη δημιουργία υβριδικού υποστρώματος με νανοσωματίδια Αργύρου το οποίο μπορεί να βρει εφαρμογή τόσο στη φωτοκατάλυση όσο και στην ανάπτυξη πιο ευαίσθητων αμπερομετρικών βιοαισθητήρων. Αρχικά περιγράφεται η λειτουργία των βιοαισθητήρων καθώς και οι σημαντικότεροι τύποι βιοαισθητήρων που έχουν κατασκευαστεί μέχρι σήμερα. Σημαντικό ρόλο στην επιτυχή κατασκευή ενός βιοαισθητήρα παίζει η επιλογή του υλικού που θα χρησιμοποιηθεί ως υπόστρωμα / ηλεκτρόδιο (στη συγκεκριμένη περίπτωση, υμένια TiO2) καθώς και ο τρόπος που ακινητοποιείται το βιομόριο πάνω σε αυτό, γι’ αυτό και έχει δοθεί έμφαση στην ανάλυση των παραπάνω πληροφοριών. Στη συνέχεια περιγράφεται η δομή και η φυσική λειτουργία της πρωτεΐνης, (κυτόχρωμα c), που χρησιμοποιήθηκε ως το βιομόριο επιλογής για την ανάπτυξη του βιοαισθητήρα. Αναλύονται οι κρυσταλλικές δομές του διοξειδίου του τιτανίου και οι βασικές φυσικοχημικές τους ιδιότητες. Επίσης γίνεται περιγραφή του φαινομένου της φωτοκατάλυσης, ενώ αναφέρονται τα πλεονεκτήματα και τα μειονεκτήματα του TiO2 για την εφαρμογή αυτή. Στο τέλος του πρώτου κεφαλαίου γίνεται αναφορά και στα νανοσωματίδια αργύρου καθώς και στους λόγους που βοηθούν στην αύξηση της φωτοκαταλυτικής απόδοσης του TiO2. Στη συνέχεια περιγράφονται οι πειραματικές διατάξεις που χρησιμοποιήθηκαν τόσο για τον χαρακτηρισμό των υμενίων TiO2 όσο και για την αναλυτική μελέτη της ακινητοποίησης του κυτοχρώματος c και των νανοσωματιδίων αργύρου πάνω σε αυτά. Περιγράφεται επίσης, η ηλεκτροχημική κυψελίδα 3 ηλεκτροδίων και οι τεχνικές της κυκλικής βολταμμετρίας και της φασματοηλεκτροχημείας που επιλέχθηκαν για τη μελέτη των ηλεκτροχημικών ιδιοτήτων των υμενίων TiO2 με ή χωρίς ακινητοποιημένη πρωτεΐνη, των υμενίων TiO2 με ακινητοποιημένα νανοσωματίδια αργύρου καθώς και για την ανάπτυξη των αμπερομετρικών βιοαισθητήρων με ευαισθησία στο H2O2. Τέλος, περιγράφεται η σύνθεση των τριών διαφορετικών παστών TiO2, η πειραματική διαδικασία εναπόθεσης των υμενίων του TiO2 σε υποστρώματα αγώγιμου υάλου και κατόπιν, ακολουθεί η ανάλυση των πειραματικών αποτελεσμάτων. / In this report 3 different types of TiO2 films were used as solid substrates for the immobilization of proteins in order to be used for the development and evaluation of amperometric biosensors for hydrogen peroxide (H2O2). The first type of thin TiO2 films were made using a Dyesol sol gel commercial TiO2 paste, the second type was produced from a TiO2 paste produced in our lab following a standard sol-gel procedure and the third type of films were produced from a paste prepared using Degusa P25 TiO2 powder. In addition, the thin TiO2 films produced from the Dyesol paste were modified with Ag nanoparticles in order to examine their electrochemical behavior which could lead to enhanced photcatalytic and/or biosensing performance. In the first chapter, a general decription of the different types of biosensors developed so far is presented and emphasis is given to their function and applications. In order to develop a successful biosensor, the choice of the material to be used as the solid substrate is very important as well as the type of the biomolecule used as the recognition element. The sensitivity and response of the biosensor is greatly enhanced by the method used to immobilize the biomolecule on the solid support in a stable and functional way. Therefore in this work both the material, TiO2 films, and the biomolecule of choice, Cytochrome-c, are presented in detail and in particular their physicochemical properties, their functions and applications. Moreover the different methods that have been used for the successful immobilization of biomolecules on solid surfaces are well documented. Furthermore, the photocatalytic properties of the TiO2 films are discussed and how they are enhanced by the deposition of silver nanoparticles on their surfaces that could also lead to the development of more sensitive and accurate amperometric biosensors. In the second chapter, the experimental techniques and procedures used for the characterization of the resulting TiO2 films and for the adsorption process of protein and/or silver nanoparticles on their surfaces are well presented. Furthermore, details are given of the electrochemical techniques (cyclic voltammetry and spectroelectrochemistry) used to evaluate the electrochemical performance of the resulting films with or without protein or silver nanoparticles. A detailed description of the 3 electrode electrochemical used to perform these experiments is also presented. Finally emphasis is given to the procedures used for the development of the electrochemical biosensors for H2O2. Finally, a description of the procedures used for the synthesis of the 3 different TiO2 pastes and of the method used for the production of thin TiO2 films on conducting glass is given followed by the presentation, analysis and discussion of the data collected.

L’explosion de la nanotechnologie a permis l’intégration d’une multitude de nanoparticules dans des produits de consommation. Les nanoparticules d’argent (nAg) sont les plus utilisées à ces fins, selon les derniers recensements disponibles. La plupart des études toxicologiques, à ce jour, ont fait état de l’implication très évidente de l’ion Ag+ dans la toxicité aigüe des nAg; cependant, quelques études ont mis en évidence des effets toxicologiques dus aux nAg. Il y a un certain consensus à propos d’un risque de contamination des eaux douces via leur rejet par les effluents des réseaux d’aqueducs. Puisque les concentrations en Ag+ sont généralement très faibles dans les eaux douces (de l’ordre du pg L-1), de par la formation de complexes non-labiles avec des thiols (organiques et inorganiques) et des sulfures, la toxicité inhérente aux nAg pourrait ne pas être négligeable- comparativement aux tests en laboratoires. Cette étude s’intéressait donc aux mécanismes de bioaccumulation d’argent par l’algue verte C. reinhardtii suite à l’exposition à des nAg de 5 nm (enrobage d’acide polyacrylique). La bioaccumulation d’argent pour l’exposition à Ag+ servait de point de comparaison; également, les abondances de l’ARNm de l’isocitrate lyase 1 (ICL1) et de l’ARNm de Copper Transporter 2 (CTR2) étaient mesurées comme témoins biologiques de la bioaccumulation de Ag+. Les expériences ont été menées en présence d’un tampon organique (NaHEPES, 2 x 10-2 M; Ca2+, 5x 10-5 M) à pH de 7,00. Pour des expositions à temps fixe de 2 heures, la bioaccumulation d’argent pour nAg était supérieure à ce qui était prédit par sa concentration initiale en Ag+; cependant, il n’y avait pas de différence d’abondance des ARNm de ICL1 et de CTR2 entre nAg et Ag+. D’un autre côté, pour une exposition à temps variables, la bioaccumulation d’argent pour nAg était supérieure à ce qui était prédit par sa concentration initiale en Ag+ et une augmentation de l’abondance de l’ARNm de ICL1 était notée pour nAg. Cependant, il n’y avait aucune différence significative au niveau de l’abondance de l’ARNm de CTR2 entre nAg et une solution équivalente en Ag+. L’ajout d’un fort ligand organique (L-Cystéine; log K= 11,5) à une solution de nAg en diminuait radicalement la bioaccumulation d’argent par rapport à nAg-sans ajout de ligand. Par contre, l’abondance des ARNm de ICL1 et de CTR2 étaient stimulées significativement par rapport à une solution contrôle non-exposée à nAg, ni à Ag+. Les résultats suggéraient fortement que les nAg généraient des ions Ag+ au contact de C. reinhardtii. / The recent developments in nanotechnology have given rise to a new and increasing economical market where nanoparticles are at the forefront. Recent inventories of the nanoparticles-containing products have shown that silver nanoparticle- containing products are the most frequently used consumer nanomaterial. Due to the fear of a large scale contamination-and even pollution- of the aquatic environment from silver nanoparticles (nAg), studies have been conducted to assess their toxicities, which, in many cases, have been found to be mediated by the concomitant presence of Ag+. Notably, few studies have found evidence of toxicity due to the nAg, per se. Since numerous non-labile complexes are formed with Ag+ in freshwaters- especially with thiols and sulfides-, nAg toxicity might be more relevant in comparison to laboratory tests where the Ag+ tends to dominate toxicity studies. Therefore, this study investigated the mechanisms underlying silver bioaccumulation by the green alga, C. reinhardtii upon exposure to solutions of nAg (nominal size of 5 nm; poly-acrylate coating). Silver bioaccumulation upon exposures to the free ion alone served for comparison. In parallel, the abundance of two mRNAs- ICL1 and CTR2- were used to better understand the mechanisms underlying the bioaccumulation of Ag+ (and potentially nAg). The experiments were conducted in pH buffered solutions (NaHEPES, 2 x 10-2 M; Ca2+, 5x 10-5 M) at pH 7.00. For 2-hour exposures, the silver bioaccumulation for solutions of nAg exceeded what was expected from their Ag+ content only; however, no differences were noticed in the abundance of the expression of ICL1 and CTR2. For variable time exposures, the silver bioaccumulation for solutions of nAg exceeded what was expected from their Ag+ content only. Moreover, the expression of ICL1 was significantly higher for nAg than what was expected based upon an exposure to Ag+ only. When exposed to nAg, expression levels of CTR2 could be predicted from levels based solely on the Ag+ concentrations. The addition of a large excess of L-Cysteine, which is a very strong silver ligand (log K =11.5), to a nAg solution largely decreased silver bioaccumulation, however, bioaccumulation remained significant and the expression of both ICL1 and CTR2 were significantly higher than that of the control solutions (without Ag+). The results strongly suggest that nAg generated Ag+ ions when in contact with C. reinhardtii and that the nAg released to freshwaters might exert its toxicity through organism-contact-dependant release of Ag+.

Das Ziel der vorliegenden Arbeit war die Entwicklung eines neuartigen Abscheideverfahrens für Dünnschichten aus Polymer-Metall-Nanokompositen sowie die Charakterisierung sensorischer und antibakterieller Eigenschaften von ersten, mit diesem System abgeschiedenen Komposit-Schichten . Durch den Einbau eines rotierenden Probenhalters zwischen den beiden Plasmaquellen ist es möglich, Plasmapolymere und metallische Nanopartikel als Einzelschichten, Komposite oder Multischichten abzuscheiden. Mit der Gasflusssputterquelle werden Silber-Nanopartikel einer Größe von 1,8…20 nm mit einer Verteilungsbreite der gewichteten Normalverteilung von 0,1…2,7 nm durch Kathodenzerstäubung und anschließende Agglomeration der Cluster in der Gasphase generiert. Die Entladungsbedingungen, welche durch die Elektronentemperatur und -dichte charakterisiert werden, zeigen eine sprunghafte Änderung bei Drücken von 70…85 Pa und einer Spannung von 550 V. Ab einem Gasfluss von 3 slpm kehrt sich die Proportionalität zwischen zugeführter elektrischer Leistung und Elektronentemperatur um. Dies wird durch die vermehrte Emission von Sekundärelektronen erklärt. Die abgeschiedenen Partikel sind aus verschieden orientierten Clustern aufgebaut. Durch Kühlung des Substrates wurde nachgewiesen, dass eine Agglomeration auf dem Substrat nur bei Gasflüssen von 5 slpm stattfindet. Anhand der Auswertung von faktoriellen Versuchsplänen wurde gezeigt, dass der Gasfluss auf die Partikelgröße und Abscheiderate den größten Einfluss hat. Die Präkursoren Styrol, Methylmethacrylat und 3-Methyl-1,2-butadien wurden durch Plasmapolymerisation in einer 60 MHz-Linearquelle als dünne, homogene Schichten im nm-Bereich abgeschieden. Aus den Emissionsspektren von Argon konnten, unter Verwendung des Stoß-Strahlungs-Modells, Elektronendichten von 6*1010…1,5*1011 cm-3 und Elektronentemperaturen von 3…9 eV in Abhängigkeit von der Verweilzeit der Monomermoleküle im Plasma sowie des Energieeintrages berechnet werden. Die Elektronen haben bei Energieeinträgen oberhalb von 6*107 J/kg genügend Energie, um -Bindungen des Kohlenstoffs in der Gasphase zu spalten. Die freien Radikale initiieren Oxidationsreaktionen, was zur Bildung von Carbonylverbindungen in Schichten aus Styrol- und Isoprenplasmapolymeren führt. Die mit XPS-Messungen gefundenen hohen Sauerstoffgehalte der Plasmapolymer-Schichten konnten durch Kontaktwinkelmessungen bestätigt werden. Die Quellungsmessungen in organischen Lösungsmitteln (Aceton, Ethanol, Chloroform, Toluol) mit reflektometrischer Interferenzspektroskpie bestätigen die Tendenzen der Kontaktwinkelmessung im Fall von Styrol und Methylmethacrylat. Die Abscheiderate der Plasmapolymere wird besonders durch den Energieeintrag beeinflusst. Dabei zeigt sich nur bei Isopren eine deutliche Auswirkung der Abbaureaktionen.Die Härte der Isopren-Schichten korreliert ebenfalls mit der Elektronendichte. Die Perkolationsschwelle der Silber-Plasmapolymer-Nanokomposite liegt bei einem Füllgrad von 57 %, was typisch für Partikel mit geringem Aspektverhältnis ist. Die Schichten reagieren selektiv auf Dämpfe der Lösungsmittel. Bisher war die Langzeitstabilität von Membranen zur Trinkwasseraufbereitung durch Ultrafiltration durch das starke Wachstum von Mikroorganismen auf der Membranoberfläche eingeschränkt. Dies konnte durch die Beschichtung mit Silber-MMA-Kompositen verbessert werden. Durchflussmessungen an behandelten Membranen sowie elektronenmikroskopische Aufnahmen bestätigen die gute antibakterielle Wirkung der Beschichtung.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A utilização de novos materiais aplicados aos processos de separação por membranas tem sido objeto de constante pesquisa acadêmica e tecnológica. Na permeação de gases petroquímicos, a modificação de estruturas poliméricas e o uso de membranas de transporte facilitado por adição de sais contendo metais ou nanopartículas destacam-se dentre as opções disponíveis. Os objetivos deste trabalho foram avaliar alterações químicas, estruturais e térmicas na matriz polimérica de poli(uretano-ureia) (PUU) provocadas pela adição de nanopartículas de prata (AgNps) e obter dados de pemeabilidade de gases petroquímicos (C2H4, C2H6, CO2 e N2) para avaliar a influência das AgNps no transporte desses gases através do filme polimérico. Alterações nos espectros de FTIR nas bandas de estiramento das ligações C-O-C e C=O (uretânica e ureica), e deslocamentos nos picos de difração, demonstram que houve interação entre as AgNps e o oxigênio éter do PUU. A interação com as AgNps diminuiu a estabilidade térmica dos domínios flexíveis do polímero, região onde são encontrados os grupos éteres. As imagens de TEM mostraram que houve baixa dispersão das Nps na matriz polimérica. A interação das AgNps com o grupo éter diminuiu a permeabilidade de todos os gases, porém a redução da permeabilidade do CO2 e do C2H4 foi muito mais significativa, mostrando a interferência das AgNps na sorção desses dois gases. O transporte facilitado de olefinas através dos filmes poliméricos não foi observado, em parte, causado pela baixa dispersão das AgNps na matriz polimérica. Apesar da interação, não foi possível responder se a superfície das Nps estava ativada para o transporte facilitado. Contudo, através dos resultados do trabalho foi possível propor um mecanismo de interação entre as AgNps e o PUU, e verificar como a presença das Nps pode alterar a interação da matriz polimérica com gases petroquímicos / The use of new materials applied to processes of membrane separation has been the target of constant academic and technological researches. In permeation of petrochemical gases, the modification of polymeric structure to form facilitated transport membranes are one of the worthy available options. In this sense, the goal of this work is, not only evaluate the influence of the addition of silver nanoparticles (AgNps) in the chemical, morphological and thermal properties of poly(urethane urea) (PUU) films, but also obtain permeability data for some petrochemical gases (C2H4, C2H6, CO2 e N2). FTIR spectra exhibited changes in the C-O-C and C=O stretching bands profile of (from urethane and urea groups) and XRD analyses exhibited shifts in peaks. These results demonstrate the AgNps interacted with the ether oxygen of PUU. The interaction with AgNps reduced the thermal stability of polymer soft segments, where the ether linkages are located. TEM images showed a lower dispersion of Np in the polymer matrix. The interaction between AgNps and ether groups also decreased the permeability of all gases. Reduction of CO2 and C2H4 permeability were clear, demonstrating the hindrance of AgNps in the sorption of both gases. The olefin transport facilitated through the polymeric films was not verified. . This is partially caused by the lower dispersion of AgNps in the polymer matrix. Although an interaction between the AgNps and ether oxygen was observed, it was not possible to confirm if the Nps surface was really activated to facilitated transport. However, considering the results obtained it was possible to propose the interaction mechanism between AgNps and PUU; and also to indicate how the presence of Nps can change the interaction between the polymeric matrix and the petrochemical gases

Submitted by DOUGLAS RICARDO DE ASSIS null (douglasnet9@hotmail.com) on 2016-03-10T00:50:50Z No. of bitstreams: 1 Dissertação de mestrado_Douglas Ricardo de Assis.pdf: 1652654 bytes, checksum: 93d244d8dfc88314c10a76a7d27326ef (MD5) / Approved for entry into archive by Sandra Manzano de Almeida (smanzano@marilia.unesp.br) on 2016-03-10T19:37:31Z (GMT) No. of bitstreams: 1 assis_dr_me_araiq_par.pdf: 232607 bytes, checksum: 0428ae381482be9888a3bad4adaa01cc (MD5) / Made available in DSpace on 2016-03-10T19:37:31Z (GMT). No. of bitstreams: 1 assis_dr_me_araiq_par.pdf: 232607 bytes, checksum: 0428ae381482be9888a3bad4adaa01cc (MD5) Previous issue date: 2016-02-19 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A auto-organização é uma das ferramentas mais versáteis e mais poderosas para a estruturação de nanopartículas em duas ou três dimensões. A técnica de Langmuir - Blodgett é o método mais promissor para a produção de filmes bidimensionais organizados de tensoativos, polímeros e nanopartículas (NPs), porque proporciona um bom controle da espessura e a homogeneidade da monocamada e de multicamadas. Esse trabalho visa sintetizar nanopartículas de Ag na interface ar-água utilizando filmes de Langmuir-Blodgett de surfactantes como suportes. A síntese das NPs de Ag na interface ar/água foi realizada de acordo com a metodologia de Khomutov e colaboradores. Foi possível sintetizar as NPs de Ag através do espalhamento da mistura das soluções de sulfadiazina de prata e ácido esteárico com razão molar de 1:1. As imagens de microscopia eletrônica de varredura de alta resolução mostram que a ausência de ácido esteárico melhorou a organização das NPs durante a síntese na interface ar/água. A composição química das NPs de prata foi determinada através da espectroscopia de energia dispersiva de raios X acoplada ao microscópio eletrônico operando no modo de varredura. Um estudo comparativo foi feito preparando-se filmes de NPs de Ag. As nanopartículas de Ag recobertas com dodecil sulfato de sódio foram sintetizadas de acordo com o método descrito por Song. As nanopartículas de Ag recobertas com polietilenoglicol (MM ≈ 3400 g.mol-1) e com ácido oléico/oleilamina foram sintetizadas pelo método poliol. Os difratogramas de raios X confirmaram a composição e a fase obtida em cada amostra. Foi estudada a composição do recobrimento das NPs através da espectroscopia na região do infravermelho e quantificado através das análises termogravimétricas. A preparação dos filmes LB de todas as amostras foi feita de acordo com o método descrito por Shin. Através das imagens de microscopia eletrônica de varredura de alta resolução observa-se que somente os filmes LB das nanopartículas de Ag recobertas com ácido oléico e oleilamina apresentam uma organização a longo alcance. Durante a formação dos filmes das amostras recobertas com SDS e com PEG3400 as nanopartículas agregaram prejudicando a organização do sistema. Esse processo de agregação pode ser atribuído a falta de surfactante na superfície das NPs ou ao excesso de polímero que aprisiona as nanopartículas no meio de suas cadeias carbônicas interferindo na organização de NPs. / Self-assembly is one of the most powerful and versatile tools for structuring nanoparticles in two or three dimensions. The Langmuir–Blodgett (LB) technique is the most promising method for production of organized surfactants, polymers, and nanoparticles (NPs) two-dimensional films, because it provides good control of the thickness and homogeneity of the mono and multilayer. This paper aims to synthesize silver nanoparticles in the air-water interface using surfactants Langmuir-Blodgett films such as “templates”. The synthesis of Ag NPs in the air / water interface was performed according the Khomutov methodology [1] it was possible to synthesize Ag NPs by spreading the mixture of silver sulfadiazine solutions and stearic acid molar ratio 1: 1. Field emission gun scanning electron microscope (FEG-SEM) images show that the absence of stearic acid improved the arrangement of NPs during synthesis in the air / water interface. The chemical composition of silver NPs was determined by energy dispersive X-ray spectroscopy attached to the electron microscope operating in scan mode. A comparative study was made preparing Ag NPs films. The Ag nanoparticles coated with sodium dodecyl sulfate were synthesized according to the method described by Song. The Ag nanoparticles coated with polyethylene glycol (MW ≈ 3400 g / mol) and oleic acid / oleylamine was synthesized by the polyol method. The X-ray diffraction confirmed the composition and phase obtained in each sample. It studied the composition of the coating of NPs through spectroscopy in the infrared region and quantified through thermogravimetric analysis. The preparation of LB films of a silver nanoparticles covered with oleic acid and olelamine (Ag@AO/OL) was done according to the methodology described by Shin et al. The images obtained by electron microscopy high resolution scan can be observed that only the LB films of Ag nanoparticles coated with oleic acid and oleylamine have an organization-reaching. During the formation of the films of the other samples the aggregated nanoparticles damaging the system organization. This aggregation process may be attributed to the lack of surfactant on the surface of the NPs or excess polymer which entraps the nanoparticles in the middle of their carbon chains interfering with NPs organization. / CNPq: 139251/2013-8

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A utilização de novos materiais aplicados aos processos de separação por membranas tem sido objeto de constante pesquisa acadêmica e tecnológica. Na permeação de gases petroquímicos, a modificação de estruturas poliméricas e o uso de membranas de transporte facilitado por adição de sais contendo metais ou nanopartículas destacam-se dentre as opções disponíveis. Os objetivos deste trabalho foram avaliar alterações químicas, estruturais e térmicas na matriz polimérica de poli(uretano-ureia) (PUU) provocadas pela adição de nanopartículas de prata (AgNps) e obter dados de pemeabilidade de gases petroquímicos (C2H4, C2H6, CO2 e N2) para avaliar a influência das AgNps no transporte desses gases através do filme polimérico. Alterações nos espectros de FTIR nas bandas de estiramento das ligações C-O-C e C=O (uretânica e ureica), e deslocamentos nos picos de difração, demonstram que houve interação entre as AgNps e o oxigênio éter do PUU. A interação com as AgNps diminuiu a estabilidade térmica dos domínios flexíveis do polímero, região onde são encontrados os grupos éteres. As imagens de TEM mostraram que houve baixa dispersão das Nps na matriz polimérica. A interação das AgNps com o grupo éter diminuiu a permeabilidade de todos os gases, porém a redução da permeabilidade do CO2 e do C2H4 foi muito mais significativa, mostrando a interferência das AgNps na sorção desses dois gases. O transporte facilitado de olefinas através dos filmes poliméricos não foi observado, em parte, causado pela baixa dispersão das AgNps na matriz polimérica. Apesar da interação, não foi possível responder se a superfície das Nps estava ativada para o transporte facilitado. Contudo, através dos resultados do trabalho foi possível propor um mecanismo de interação entre as AgNps e o PUU, e verificar como a presença das Nps pode alterar a interação da matriz polimérica com gases petroquímicos / The use of new materials applied to processes of membrane separation has been the target of constant academic and technological researches. In permeation of petrochemical gases, the modification of polymeric structure to form facilitated transport membranes are one of the worthy available options. In this sense, the goal of this work is, not only evaluate the influence of the addition of silver nanoparticles (AgNps) in the chemical, morphological and thermal properties of poly(urethane urea) (PUU) films, but also obtain permeability data for some petrochemical gases (C2H4, C2H6, CO2 e N2). FTIR spectra exhibited changes in the C-O-C and C=O stretching bands profile of (from urethane and urea groups) and XRD analyses exhibited shifts in peaks. These results demonstrate the AgNps interacted with the ether oxygen of PUU. The interaction with AgNps reduced the thermal stability of polymer soft segments, where the ether linkages are located. TEM images showed a lower dispersion of Np in the polymer matrix. The interaction between AgNps and ether groups also decreased the permeability of all gases. Reduction of CO2 and C2H4 permeability were clear, demonstrating the hindrance of AgNps in the sorption of both gases. The olefin transport facilitated through the polymeric films was not verified. . This is partially caused by the lower dispersion of AgNps in the polymer matrix. Although an interaction between the AgNps and ether oxygen was observed, it was not possible to confirm if the Nps surface was really activated to facilitated transport. However, considering the results obtained it was possible to propose the interaction mechanism between AgNps and PUU; and also to indicate how the presence of Nps can change the interaction between the polymeric matrix and the petrochemical gases

Made available in DSpace on 2015-05-14T13:21:16Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 3817465 bytes, checksum: 48db05ac5b1af395dffcbde5a5601151 (MD5) Previous issue date: 2012-08-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study consists of the acquisition, characterization and evaluation of antimicrobial silver nanoparticles and nanostructured Ag/ZnO. The silver nanoparticles were obtained through a new route using AgNO3 as precursor salt and ammonium citrate as reducing agent. Concerning the commercial zinc oxide, silver nanoparticles were impregnated using the microwave hydrothermal method at different synthesis times. Samples of Ag / ZnO nanostructured were characterized by using techniques of X-Ray Diffraction (DRX), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The colloidal silver nanoparticles obtained during the processes were characterized through optical spectroscopy in the ultraviolet and visible (UV-Vis) regions. Antimicrobial activity assays were carried for the Ag / ZnO nanostructured and for colloidal silver nanoparticles. They were included six bacteria species as well as six fungal species. Analysis of toxic and cytotoxic activity was performed for colloidal silver nanoparticles on fingerlings of Poecilia Reticulata and Artemia salina. The results show that the chosen synthesis method is effective for silver synthesis, as well as for the process of impregnation of the silver nanoparticles on the commercial zinc oxide. The biological tests revealed significant antimicrobial activity of silver nanoparticles on the micro-organisms analyzed and their low toxicity. / Este trabalho consiste na obtenção, caracterização e avaliação antimicrobiana de nanopartículas de prata e Ag/ZnO nanoestruturado. As nanopartículas de prata foram obtidas através de uma nova rota utilizando AgNO3 como sal precursor e citrato de amônio como agente redutor. Sobre óxido de zinco comercial foram impregnadas nanopartículas de prata por meio do método hidrotermal de micro-ondas em diferentes tempos de síntese. As amostras Ag/ZnO nanoestruturado foram caracterizadas através das técnicas de difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). As nanopartículas de prata coloidais obtidas durante os processos foram caracterizadas por meio da espectroscopia óptica na região do ultravioleta e visível (UV-Vis). Ensaios de atividade antimicrobiana foram procedidos para o Ag/ZnO nanoestruturado e para as nanopartículas de prata coloidal. Foram incluídas seis espécies bacterianas e seis espécies fúngicas. Análises da atividade tóxica e citotóxica, foram procedidas para as nanopartículas de prata coloidal sobre alevinos de Poecilia Reticulata e sobre Artemia salina. Os resultados demostram que método de síntese escolhido se mostrou eficaz para a síntese da prata, bem como no processo de impregnação das nanopartículas de prata sobre o óxido de zinco comercial. Os testes biológicos revelaram significativa atividade antimicrobiana das nanopartículas de prata sobre os micro-organismos analisados e a sua baixa toxidade.