Submitted by GRAZIELA CRISTINA SEDENHO null (grasedenho@yahoo.com.br) on 2016-02-12T19:43:04Z No. of bitstreams: 1 Dissertação_Graziela Cristina Sedenho.pdf: 4075574 bytes, checksum: 8d8fa0c583e32e2f42a6d7092c393844 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-16T15:44:23Z (GMT) No. of bitstreams: 1 sedenho_gc_me_araiq_par.pdf: 955629 bytes, checksum: 812d933588fa4febf4bd052f9afbeddf (MD5) / Made available in DSpace on 2016-02-16T15:44:23Z (GMT). No. of bitstreams: 1 sedenho_gc_me_araiq_par.pdf: 955629 bytes, checksum: 812d933588fa4febf4bd052f9afbeddf (MD5) Previous issue date: 2016-01-07 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O etanol é um importante componente da matriz energética brasileira, sendo produzido a partir da cana-de-açúcar. Nesse processo de produção, é produzida vinhaça como subproduto, a qual para cada 1 L de etanol gera-se de 12 L a 18 L. A vinhaça é constituída principalmente de sais de potássio, cálcio e magnésio e compostos orgânicos. Dentre estes, os ácidos carboxílicos tornam-se importantes por estarem presentes em concentrações significativas na vinhaça de cana-de-açúcar e por apresentarem expressiva importância industrial. Sendo assim, nesse trabalho foi desenvolvido um detector eletroquímico baseado em eletrodos de diamante dopado com boro quimicamente modificados com nanopartículas de níquel (NiNPs-BDD) e de cobre (CuNPs-BDD) para determinação dos ácidos lático, málico e tartárico em vinhaça de cana-de-açúcar utilizando a técnica de cromatografia líquida de alta eficiência (CLAE) de troca iônica. Imagens de microscopia eletrônica de varredura e espectros de raios X por dispersão em energia, em conjunto com os experimentos eletroquímicos, mostraram que os eletrodos de BDD foram efetivamente modificados com nanopartículas de óxido-hidróxido de níquel e óxido de cobre com diâmetros médios de 89 nm e 91 nm, respectivamente. Os estudos voltamétricos mostraram que as oxidações dos ácidos lático, málico e tartárico, em meio básico, se dão em potenciais em torno de 0,50 V (vs. Ag/AgCl) e 0,73 V (vs. Ag/AgCl), nos eletrodos NiNPs-BDD e CuNPs-BDD, respectivamente, e são mediadas pelas espécies Ni3+ e Cu3+. O eletrodo de NiNPs-BDD foi utilizado em CLAE com detecção amperométrica pulsada. A coluna de troca aniônica CarboPac PA1 foi utilizada para separação dos ácidos carboxílicos em vinhaça. Empregou-se como fase móvel água deionizada e 0,10 mol L-1 de NaOH em 0,25 mol L-1 de CH3COONa, sob fluxo de 1,0 mL min-1. O potencial de detecção empregado foi 0,48 V vs. Pd. O eletrodo de NiNPs-BDD apresentou boa estabilidade nas condições cromatográficas, tornando viável a sua utilização como detector amperométrico em CLAE. O tempo de análise foi de 27 min e não foi necessário um procedimento complexo e dispendioso de preparo de amostra. As sensibilidades analíticas foram 7,5 × 103 nA L mol-1, 3,5 × 104 nA L mol-1 e 5,4 × 105 nA L mol-1 para os ácidos lático, málico e tartárico, respectivamente. Os limites de detecção foram 1,2 × 10-4 mol L-1, 6,1 × 10-5 mol L-1 e 2,8 × 10-5 mol L-1, respectivamente. As concentrações dos ácidos carboxílicos em vinhaça de cana-de-acúcar foram determinadas pelo método de adição de padrão como sendo (1,2 ± 0,3) × 10-1 mol L-1, (2,7 ± 0,6) × 10-3 mol L-1 e (9,9 ± 1,0) × 10-4 mol L-1 para os ácidos lático, málico e tartárico, respectivamente. Ensaios de recuperação mostraram que o método analítico desenvolvido possui boa exatidão e precisão, podendo ser considerado adequado para a detecção e quantificação dos ácidos lático, málico e tartárico em vinhaça de cana-de-açúcar. O eletrodo de CuNPs-BDD foi empregado na célula amperométrica do cromatógrafo, no entanto não apresentou boa estabilidade nas condições cromatográficas, o que impossibilitou sua utilização na determinação dos compostos de interresse na vinhaça de cana-de-açúcar. / Ethanol is an important component of the Brazilian energy matrix, being produced from sugarcane. In this producing procedure, vinasse is produced as by-product, which for every 1 L of ethanol is generated from 12 L to 18 L. The vinasse is basically composed by salts of potassium, calcium and magnesium and organic compounds. Among these, carboxylic acids are important because they are present in significant concentrations in the sugar cane vinasse and show significant industrial importance. Thus, in this work it was developed an electrochemical detector based on boron-doped diamond electrodes chemically modified with nickel nanoparticles (NiNPs-BDD) and copper nanoparticles (CuNPs-BDD) for the determination of lactic acid, malic acid and tartaric acid in vinasse from sugarcane using high-performance liquid chromatography (HPLC) by ion exchange. Images of scanning electron microscopy and spectra of energy-dispersive X-ray in conjuction with electrochemical experiments showed the electrodes of BDD were effectively modified with nickel oxide-hydroxide nanoparticles and copper oxide nanoparticles with diameters of 89 nm and 91 nm, respectively. The voltammetric studies showed the oxidations of lactic acid, malic acid and tartaric acid, in basic medium, tooke place at potentials around 0.50 V (vs. Ag/AgCl) and 0.73 V (vs. Ag/AgCl) at NiNPs-BDD and CuNPs-BDD electrodes, respectively, and they are mediated by Ni3+ and Cu3+ species. NiNPs-BDD electrode was used in HPLC with pulsed amperometric detection. The anion exchange column CarboPac PA1 was used for separation of carboxylic acids in vinasse. It was employed as mobile phase deionized water and 0.10 mol L-1 NaOH in 0.25 mol L-1 CH3COONa under flow of 1.0 mL min-1. The detection potential was 0.48 V vs. Pd. The NiNPs-BDD electrode showed good stability under chromatographic conditions, becoming feasible its use as amperometric detector for HPLC. The analysis time was 27 min and no complex and expensive sample preparation procedure was required. The analytical sensitivities were 7.5 × 103 nA mol-1 L, 3.5 × 104 L mol-1 nA and 5.4 × 105 L mol-1 nA for lactic, malic and tartaric acids. The detection limits were 1.2 × 10-4 mol L-1, 6.1 × 10-5 mol L-1 and 2.8 × 10-5 mol L-1, respectively. The concentrations of the carboxylic acids in sugar cane vinasse were determined by the standard addition method to be (1.2 ± 0.3) × 10-1 mol L-1, (2.7 ± 0.6) × 10-3 mol L-1 and (9.9 ± 1.0) × 10-4 mol L-1 for lactic acid, malic acid and tartaric acid, respectively. Recovery tests showed the analytical method has good accuracy, being considered suitable for the detection and quantification of lactic acid, malic acid and tartaric acid in sugarcane vinasse. CuNPs-BDD electrode was used in the amperometric cell of the chromatograph, however it did not show good stability in the chromatographic conditions, and it could not be employed in the determination of compounds of interest in sugarcane vinasse. / FAPESP: 2013/09833-5 / FAPESP: 2014/10391-0

A reação de redução de oxigênio (RRO) foi estudada em eletrocatalisadores formados por nanopartículas de óxidos puros e mistos de metais de transição de Mn, Co e Ni, além de estrutura tipo espinel, e por nanopartículas de Ag, Au e Ag3M (M= Au, Pt, Pd e Cu) suportadas em carbono Vulcan, em eletrólito alcalino. Os óxidos de metais de transição foram sintetizados por decomposição térmica de seus respectivos nitratos e as nanopartículas a base de prata e ouro foram sintetizadas por redução química com borohidreto. Os eletrocatalisadores foram caracterizados por Difratometria e Espectroscopia de Absorção de Raios X (somente para os óxidos de transição). Os materiais a base de óxidos de manganês, mostraram-se com alta atividade para a RRO, para os quais os resultados espectroscópicos in situ evidenciaram a ocorrência da redução do Mn(IV) para Mn(III), na região de início da RRO. Assim, as atividades eletrocatalíticas foram associadas à ocorrência da transferência de elétrons do Mn(III) para o O2. Entretanto, apresentaram forte desativação após ciclagem potenciodinâmica, o que foi associado à formação da fase Mn3O4, conforme indicado por difratometria de Raios X, após os experimentos eletroquímicos, que é eletroquimicamente inativa. Já o material formado pela estrutura do tipo espinel de MnCo2O4 apresentou alta atividade e estabilidade frente à ciclagem e à RRO. A alta atividade eletrocatalítica foi relacionada a ocorrência do par redox CoII/CoIII em maiores valores de potencial em relação ao CoOx e MnOx, devido a interações entre os átomos de Co e Mn no reticulo espinélico. Contrariamente ao observado nos óxidos com maior quantidade de manganês, o espinel mostrou-se altamente estável, o que foi associada à não alteração de sua estrutura no intervalo de potenciais que a RRO ocorre. Para os materiais bimetálicos a base de prata e ouro, os experimentos eletroquímicos indicaram maior atividade eletrocatalítica para o material de Ag3Au/C. Neste caso, a alta atividade foi associada a dois efeitos principais: (i) a um efeito sinergético, no qual os átomos de ouro atuam na região de ativação, favorecendo a adição de hidrogênio e os átomos vizinhos de prata proporcionam a quebra da ligação O-O, conduzindo a RRO pelo caminho de quatro elétrons por molécula de O2; (ii) ao aumento força da ligação Ag-O, devido à interação da Ag com o Au, resultando em maior atividade para a quebra da ligação O-O, aumentando a atividade da Ag para a RRO, em relação à atividade da Ag pura. Assim, a RRO apresentou menor sobrepotencial e maior número de elétrons em Ag3Au/C, quando comparado com as demais nanopartículas bimetálicas. / The oxygen reduction reaction (ORR) was studied on electrocatalysts composed by pure and mixed transition metal oxides of Mn, Co, and Ni, including spinel-like structures, and by Ag, Au, and Ag3M/C (M= Au, Pt, Pd e Cu) bimetallic nanoparticles, in alkaline electrolyte. The transition metal oxides were synthesized by thermal decomposition of their nitrates, and the silver and gold-based nanoparticles by chemical reduction using borohydride. The electrocatalysts were characterized by X-Ray Diffraction and X-Ray Absorption Spectroscopy (in the case of the metal oxides). The manganese-based oxide materials showed high activity for the ORR, in which the in situ spectroscopic results evidenced the Mn(IV) to Mn(III) reduction, in the range of the ORR onset. In this case, the electrocatalytic activities were correlated to the transfer of electron from Mn(III) to O2. However, they presented strong deactivation after several potentiodynamic cycles, which was ascribed to the formation of the electrochemically inactive phase of Mn3O4, as indicated by the XRD results, after the electrochemical experiments. On the other hand, the MnCo2O4 spinel-like material showed high activity and stability for the ORR. Its high electocatalytic activity was attributed to the CoII/CoIII redox pair, taking place at higher potentials, in relation to that of the CoOx e MnOx pure phases, due to the Co and Mn interactions in the spinel lattice. Contrarily to the behavior observed for the manganese-based materials, the spinel oxide presented high stability, which was ascribed to the non alteration of its crystallographic structure in the range of potentials tha the ORR takes place. For the Au and Ag-based materials, the electrochemical experiments indicated higher electrocatalytic activities for Ag3Au/C. In this case, its higher activity as associated to two main aspects: (i) to a synergetic effect, in which the gold atoms act in the activation region, facilitating the hydrogen addition, and the neighboring Ag atoms promoting the O-O bond breaking, leading the ORR to the 4-electrons pathway; (ii) to the increased Ag-O bond strength, due to the electronic interaction between Ag and the Au atoms, resulting in a faster O-O bond breaking, enhancing the electrocatalytic activity of the Ag atoms in the Ag3Au/C nanoparticle, in relation to that on the pure Ag. Therefore, the ORR presented lower overpotential and higher number of electrons in the Ag3Au/C electrocatalyst, when compared to the other investigated bimetallic nanoparticles.

This thesis summarizes the methods of preparation and optical properties of hybrid assemblies of Au NPs and cadmium selenide (CdSe) QDs. First chap-ter deals with the literature survey and theoretical aspects of plasmonics and discussions on optical excitations of metal (plasmons) and semiconducting QDs (excitons). Variation of energy levels of CdSe QDs and its optical properties i e. absorption and emission properties under strong confinement regime have been discussed with respect to effective mass approximation (EMA) model. This is followed by the discussion on optical properties of Au NPs and rods, describing absorption properties, based on Mie theory. Size and shape depen-dent variation of absorption properties. Theoretical discussions of collective effects in QDs assemblies and plasmonic interactions with the QDs assemblies i.e. plasmonic Dicke effect and metal nanoantenna interaction with CdSe QDs arrays is provided. In the second chapter a discussion on experimental techniques used for the study is provided. It starts with a discussion on the synthesis methods for CdSe QDs and Au NPs/rods with different capping ligands. Different techniques of preparation of CdSe QDs assemblies and their hybrid with metallic nanoparti-cles has been discussed. Further discussion on optical microscopy techniques, confocal, near field scanning microscopy (NSOM), Brewster angle microscopy and electron microscopy techniques i. e transmission electron microscopy and scanning electron microscopy and thermogravimetry analysis of the samples is provided. In the third chapter the details of the different self-assembly methods of preparation of hybrid assemblies of CdSe QDs and Au NPs /rods are given. The different strategies are used for different type of hybrids. In first method of Langmuir-Blodgett (LB) , effect of different capping agents, core size, and number ratios of Au NPs/rods to CdSe QDs, effect of anisotropy of Au NPs on the LB films of CdSe QDs assemblies is discussed. In another method of dip coating several control parameters like dip time, concentration of the solution and dip speed of transferring an aligned GNRs is given. Finally a combination of LB and dip coating methods is described for transferring aligned GNRs over a compact layer of CdSe QDs. At the end, a section is devoted to hit and trials of self-assemblies of hybrid of GNRs and CdSe QDs using LB method, the failures of which resulted in devising a method which uses a combination of LB and dip coating. In fourth chapter effects of plasmons on the collective emission of CdSe QDs assemblies are investigated. A plasmonic tuning of photoluminescence from semiconducting QD assemblies using Au NP in different ratio and different packing density has been discussed. We have described how the emission from a closed pack assemblies, prepared with different packing densities depends on the packing density and extent of spectral overlap between QD photolumi-nescence and the metal nanoparticle absorbance. We have provided possible evidence for plasmon mediated coherent emission enhancement from some of these assemblies from the case of strong spectral overlap between CdSe QDs and Au nanoparticle. In fifth chapter, we have demonstrated non local far field enhancement of PL in QDs assemblies induced by isolated and partially aligned GNRs nano-antenna located on such assemblies. It is shown that the emission is also anisotropic with the maxima being near such GNRs assembly which decays to finite, nonzero and significantly large values even away from the vicinity of any such assemblies. For this novel effect it is shown to have a clear spec-tral dependence. It is shown to be maximum when the longitudinal surface plasmon resonance absorption maxima is resonant with the CdSe QD photolu-minescence maxima and the excitation wavelength and is always non-existent for the off resonant case. We have also shown that finite difference time do-main simulations could model some of the observed near field effects but the far field effects could not be modelled in such simulations.

This thesis deals with guided self-assembly of gold nanoparticles from their colloidal solutions onto silicon substrates and possible employment of nanoparticles for detection of biomolecules. It was found that by adjustment of solution pH and surface chemistry modification by means of electron beam irradiation it is possible to facilitate nanoparticle deposition to patterns with almost single particle precision. Spectroscopic ellipsometry was then employed in analysis of self-assembled layers of nanoparticles and its combination with a theory of effective medium approximation has proven the ability to assess nanoparticle dimensions and volume fractions. By experiments with thiolated oligonucleotides it has been shown that using ellipsometry one can detect even with very subtle changes in nanoparticle environment caused by biomolecules, thus promising its possible use in the field of biodetection.

This thesis deals with the dark-field imaging and the optical spectroscopy of optically trapped plasmonic nanoparticles. The optical trapping and the characterization of a single particle or multiple nanoparticles as well are demonstrated. The number of the optically trapped particles can be estimated from the dark-field scattering intensity. Experiments show the presence of the interparticle coupling among trapped metallic nanoparticles which has not been observed in case of dielectric particles. The scattering spectra of the plasmonic nanoparticles were compared with theoretical models based on the Mie theory and the Discrete dipole approximation.

Cette thèse est consacrée à l'étude de l'interaction d'ions multichargés avec des particules métalliques de taille nanométrique. Ce travail a eu pour but d'étudier les processus fondamentaux ainsi que d'éclairer leur rôle comme radio-sensibilisants dans le traitement de cancer par hadronthérapie. Le nouveau dispositif développé dans ce cadre consiste en une source d'agrégats de type magnétron, d'une chambre de dépôt afin de permettre la caractérisation de la taille des nanoparticules neutres par analyse microscopique, et d'un spectromètre de masse par temps de vol capable de détecter des systèmes positivement chargés jusqu'à une masse de 50 000 ua. Les études de collisions ont été réalisées avec des agrégats de Bi (2 nm ; 200 atomes) et de Ag (6 nm ; 5000 atomes). Dans le deux cas, le processus de capture multiélectronique crée un système multichargé. Dans le cas du Bi, une grande partie fragmente par la fission asymétrique émettant des petits fragments. Dans le cas des particules plus grandes (Ag), les systèmes multichargés ne fragmentent pas, par contre des petits fragments sont aussi observés mais ils sont le produit de la pulvérisation de la nano-surface lors de collisions pénétrantes. En perspective, des expériences seront réalisées avec des nanoparticules métalliques fonctionnalisées ainsi que le comptage des électrons émis lors de la collision. / This thesis presents a study of the interaction of multiply charged ions with metallic nano-sized particles both in the context of fundamental processes and possible applications as radiosensitizers in nanoparticle-enhanced hadrontherapy. For this purpose a new experimental set-up has been constructed based on a magnetron-discharge cluster source, a deposition chamber for analyzing the size of neutral nanoparticles with AFM and TEM techniques and a time-of-flight mass spectrometer able to detect positively charged particles with masses up to 50 000 amu. Collision studies were performed with Bi clusters of 2nm in diameter, containing 200 atoms, as well as Ag nanoparticles (6 nm, 5000 atoms). In both cases multi-electron capture leads to the formation of multiply charged systems. In the Bi case a large fraction fragments by asymmetric fission emitting small singly charged fragments. In the case of large Ag nanoparticles multiply charged systems are stable. However, small size fragments are formed due to sputtering of the nano-surface in penetrating collisions. Future experiments will be performed with functionalized metal nanoparticles, aiming to count the number of electrons emitted after ion collisions.

In der vorliegenden Dissertation werden verschiedene plasmonisch aktive Kern/Schale- Nanopartikel synthetisiert, experimentell und theoretisch charakterisiert und in analytischen Anwendungen der oberflächenverstärkten Raman-Spektroskopie (engl. surface-enhanced Raman scattering, SERS) eingesetzt. Es werden die optischen Eigenschaften von Gold/Silber-Nanoschalen mit durchstimmbaren Plasmonbanden behandelt. Motivation dafür ist die Frage nach optimalen SERS-Markern für die rote Laseranregung (λ = 632.8 nm). In SERS-Anwendungen gibt es die Möglichkeit mehrere Marker-Moleküle auf die Oberfläche der Nanopartikel aufzubringen, um so eine erhöhte Multiplexing-Kapazität zu generieren. Diese Option der gemischten Monolagen wird in der vorliegenden Arbeit untersucht. Es werden SERS-Marker-Konzepte für die rote Laseranregung basierend auf einzelnen Nanopartikeln gezeigt. Außerdem wird dargestellt, inwieweit sich durch die Anordnung von Nanopartikeln in allen drei Raumdimensionen neue SERS-Marker- Konzepte mit sehr guten plasmonischen Eigenschaften realisieren lassen. In den oben beschriebenen Kapiteln übernehmen Nanopartikel die Rolle des SERS-Substrats für den selektiven Nachweis eines bestimmten Zielmoleküls (z.B. Antigens). Neben diesen Anwendungen können Nanopartikel jedoch auch noch als SERS-Substrat für die markierungsfreie Detektion von Analytmolekülen eingesetzt werden. In dieser Dissertation wird die Herstellung, Charakterisierung und der Einsatz eines integrierten SERS-Substrats für die kombinierte Festphasensynthese und Analytik mittels plamonisch aktiver Gold/Glas-Kern/Schale-Nanopartikel auf Harz-Mikrokugeln behandelt.

Nanomaterial produceras och används alltmer i tekniska lösningar för att förbättra t.ex. materialegenskaper. Eftersom ett materials egenskaper förändras när det är i nanoskala så påverkas även dess toxikologiska egenskaper. För närvarande finns det ett flertal rapporter om oavsiktligt bildande av metalliska nanopartiklar, Me NPs, vid byggarbetsplatser, vilket riskerar att byggarbetarna exponeras för att andas in dessa partiklar.  På grund av nanomaterialens storleksberoende egenskaper så är inte dagens toxikologiska utvärderingsmetoder sällan anpassade för dessa typer av material. Att undersöka växelverkan mellan Me NPs och pulmonella biomolekyler och utveckla metoder för analys därför av hög prioritet.  I detta examensarbete har en metod för upplösning av det pulmonellt ytaktiva ämnet fosfolipid 1,2-dipalmitoylfosfatidylkolin, DPPC, baserat på sonikering i vattenbad testats och utvärderats. Den simulerade lungvätskan Gambles lösning har testats och utvärderats som en möjlig lösning för att studera växelverkan mellan DPPC och Co NPs. Växelverkan mellan dess komponenter och Co NPs har studerats med hjälp av PCCS, NTA samt ATR-FTIR. Då examensarbetet genomfördes under den pågående Covid-19 pandemin har anpassningar i det experimentella arbetet gjorts med hänsyn till det rådande läget. PCCS visade att vid upplösning av DPPC i lösningen så minskade sonikering omfattningen av sedimentationen och den resulterande storleken på liposomerna låg inom intervallet mellan 50 och 70 nm i ultrarent vatten och mellan 30 och 40 nm i Gamble’s lösning. Skillnaden i liposomstorlek tros bero av växelverkan mellan komponenterna i Gamble’s lösning och DPPC, vilket även observerades med FTIR och överensstämmande med litteraturen. Den relativa skillnaden i liposomstorlek i de olika lösningarna observerades också med NTA, men experimentella problem kan ha påverkat resultaten. Gamble’s lösning hade en inverkan på Co NPs i lösningen, bland annat genom att uppmätta partikelkoncentrationer bestämde med hjälp av PCCS och NTA var mindre än hälften av motsvarande koncentration initialt i ultrarent vatten (vid 0 h). En trolig förklaring är att den högre jonstyrkan hos Gamble’s lösning orsakar snabb sedimentation och/eller snabb upplösning av Co NPs. Tillsättning av DPPC till en lösning av Co NPs i Gamble’s lösning släckte ut effekten, vilket indikerar en växelverkan mellan Co NPs och komponenter i Gamble’s lösning. Jämförelse av normaliserade integraler från ATR-FTIR med DPPC i Gamble’s lösning utan Co NPs och när lösningen exponerades för en Co NP film visade en signifikant skillnad efter 90 min och vid sköljning. Baserat på projektets resultat så föreslås Gamble’s lösning att bytas ut på grund av dess växelverkan med de olika komponenterna samt att liposomstorleken studeras mer i detalj. Framtida studier uppmuntras omfatta en upprepning av ATR-FTIR- mätningarna samt en frisättningsstudie av Co NPs i olika lösningar. / Nanomaterials, NMs, are increasingly produced and applied in technical applications to enhance, e.g. material properties. Since material properties change when in nanoscale, they influence their toxicological properties. There are also numerous reports of incidental formation of metallic nanoparticles, Me NPs, at construction sites, which may place workers at risk of occupational exposure by inhaling these materials. However, because of NMs size-dependent properties, current standard toxicological evaluation methods are not always well suited to these types of materials. Investigations into interactions between Me NPs and pulmonary biomolecules and method development for analysis of these interactions are therefore of high priority. In this master thesis, a description on how to dissolve the pulmonary surface active phospholipid 1,2-dipalmitoylphosphatidylcholine, DPPC, via water bath sonification has been elaborated and evaluated. The simulated lung fluid, Gamble’s solution, has been tested and evaluated as a possible medium to study interactions between DPPC and cobalt (Co) NPs under more realistic laboratory conditions. Interactions between the sample components have been studied using Photon cross-correlation spectroscopy, PCCS, Nanoparticle Tracking Analysis, NTA, and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy, ATR-FTIR. Since the master thesis study was conducted during the onset of the Covid-19 pandemic, adjustments related to experimental work had to be made. PCCS showed that sonication of the DPPC solution reduced the extent of sedimentation, and the resulting size range of liposomes in solution was in the range between 50 and 70 nm in ultrapure water and between 30 and 40 nm in Gamble’s solution. Observed differences in liposome size are believed to be due to the interaction between the components of Gamble’s solution and the DPPC. This was also observed in the IR- spectra and comparable with literature findings. NTA measurements similarly visualize the relative difference in the size of the liposomes in the different media, but difficulties with the experiments may have affected the results. Gamble’s solution affected the Co NPs, such that measured particle concentrations of the NPs by means of PCCS and NTA were approximately less than half of the initial observations in ultrapure water (at 0 h). A likely explanation is that the high ionic strength of Gamble’s solution induces either fast sedimentation and/or rapid dissolution of the Co NPs. The addition of DPPC to Co NPs in Gamble’s solution cancelled this effect and suggest interactions between Co NPs and Gamble’s solution. Comparison of the normalized integrals of the ATR-FTIR- spectra of DPPC in Gamble’s solution with and without exposure to a Co NP film showed a significant difference after 90 min and upon rinsing the flow cell. Based on these results, an alternative to Gamble’s solution is suggested due to its interaction with other experimental components and that DPPC is used at a lower concentration investigation on liposome sizes are made in more detail. In addition, the ATR-FTIR measurements should be repeated, and dissolution studies of Co NPs in different synthetic media are encouraged in future studies.

Ce travail vise à utiliser des surfaces d'alumine nanostructurées pour guider la croissance et l'organisation de particules métalliques (Ag, Au et AgxAu1-x), et à les tester en tant que substrats SERS-actifs robustes et réutilisables. Nous avons utilisé la spectrophotométrie pour la caractérisation des propriétés optiques résultantes, l'ellipsométrie spectroscopique pour l'extraction des indices optiques et la microscopie électronique en transmission pour les caractérisations structurales. La diffusion Raman exaltée de surface (SERS) a été utilisée pour la détection de molécules de bipyridine adsorbées sur la surface des échantillons, en collaboration avec l’Institut des Matériaux Jean Rouxel de Nantes. Nous étudions d'abord des systèmes de nanoparticules monométalliques et bimétalliques afin de comprendre les modes de croissance de telles assemblées. Nous montrons que des arrangements différents de nanoparticules bimétalliques sont obtenus selon la séquence de dépôt utilisée et qu'un alliage est obtenu à l'issue de recuits ex situ sous vide. Les propriétés optiques en champ proche et lointain de nanoparticules d'alliage AgxAu1-x noyées dans une matrice d'Al2O3 sont comparées numériquement à celles des métaux purs, par la méthode de calcul des différences finies dans le domaine temporel. Les résultats indiquent que l’amplification du champ pour les nanoparticules de métal pur est plus élevée que pour les nanoparticules d’alliage. Enfin, les expériences SERS menées sur un système dichroïque de nanoparticules d’Ag plus ou moins couplées montrent que l'on peut obtenir un signal SERS intense avec des nanoparticules recouvertes. / The aim of this work is to use nanostructured alumina surfaces to guide the growth and to optimize the organization of metallic particles (Ag, Au and AgxAu1-x), and to test those systems as reusable SERS-active substrates. We used spectrophotometry to characterize the resulting optical properties, spectroscopic ellipsometry for the determination of the optical index and transmission electron microscopy for the structural characterizations. Surfaced-enhanced Raman spectroscopy (SERS) was used for the detection of adsorbed bipyridine molecules on the sample surface, in collaboration with the Institut des Matériaux Jean Rouxel at Nantes. We first study systems consisting of monometallic and bimetallic nanoparticles in order to understand the growth modes of such particle assemblies. A particular attention is paid to the influence of the sequential deposition of Au and Ag on the structural and optical properties. We show that different arrangements of bimetallic nanoparticles are obtained according to the deposition sequence used and that an alloy is obtained after ex situ annealing under vacuum. The near-field and far-field optical properties of AgxAu1-x nanoparticle alloys embedded in an alumina matrix are compared numerically by the finite difference time domain method, with those of pure metal nanoparticles. Our results indicate that pure metal nanoparticles exhibit a greater field enhancement than alloy nanoparticles. Finally, SERS experiments conducted with a dichroic system made of coupled Ag nanoparticles show that an intense SERS signal can be obtained with coated nanoparticles.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-01-26T17:16:54Z No. of bitstreams: 1 thalesalvesfaraco.pdf: 2957993 bytes, checksum: bfe51ef9cf732341f404484ab0aaea79 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-01-29T10:56:06Z (GMT) No. of bitstreams: 1 thalesalvesfaraco.pdf: 2957993 bytes, checksum: bfe51ef9cf732341f404484ab0aaea79 (MD5) / Made available in DSpace on 2018-01-29T10:56:06Z (GMT). No. of bitstreams: 1 thalesalvesfaraco.pdf: 2957993 bytes, checksum: bfe51ef9cf732341f404484ab0aaea79 (MD5) Previous issue date: 2015-02-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Vidros fosfatos são materiais tecnologicamente importantes, devido às suas propriedades físicas e químicas, podendo ser aplicados em sistemas ópticos, através da co-dopagem com íons terras raras e nanopartículas metálicas. São apresentados, neste trabalho, a produção pela técnica de fusão/resfriamento e a caracterização de vidros fosfato de silício dopados com trióxido de érbio 23 e/ou nitrato de prata 3, para a verificação da influência desses dopantes, quando adicionados à matriz hospedeira, nas propriedades térmica, ópticas e estruturais. As amostras foram submetidas a tratamento térmico e às técnicas de caracterização: Densidade, Índice de Refração Linear (IRL), Análise Térmica Diferencial (ATD), Absorção Óptica (AO), Fotoluminescência de Estado Estacionário (FL) e Fotoluminescência Resolvida no Tempo (FLRT); onde através delas e dos cálculos de Judd-Ofelt foi possível mapear características promissoras desses vidros para aplicações tecnológicas, com destaque em telecomunicação: transmissão de dados por fibras ópticas. / Phosphate glasses are technologically important materials due to their physical and chemical properties and can be applied in optical systems by co-doping with rare earth ions and metallic nanoparticles. In this work the production by melting and quenching technique and characterization of phosphate silica glasses doped with trioxide erbium and / or silver nitrate are shown, so that can checked the influence of these dopants, when added to the host matrix, in thermal, optical and structural properties. The samples were subjected to heat treatment and the characterization techniques: Density, Linear Refractive Index (LRI), Differential Thermal Analysis (DTA), optical absorption (OA), steady state photoluminescence (PL) and Time Resolved Photoluminescence (TRPL), where through them and Judd-Ofelt calculations, promising features of these glasses could be mapped for technological applications, especially in telecommunication: data transmission by optical fibers.