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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Bipolar electrochemistry for high throughput screening applications

Munktell, Sara January 2016 (has links)
Bipolar electrochemistry is an interesting concept for high throughput screening techniques due to the ability to induce gradients in a range of materials and their properties, such as composition, particle size, or dopant levels, among many others. One of the key advantages of the method is the ability to test, create or modify materials without the need for a direct electrical connection. In this thesis, the viability of this method has been explored for a range of possible applications, such as metal recycling, nanoparticle modification and corrosion analysis. In the initial part of the work a process to electrodeposit gradients in metal composition was evaluated, with a view to applying the technique to the extraction and recycling of metals from fly ash. Compositional gradients in the metals under study could be readily obtained from controlled reference solutions, although the spatial resolution of the metals was not sufficient to perform separation. Only copper could be easily deposited from the fly ash solution. Bipolar electrodeposition was also successfully used to modify the particle size across substrates decorated with gold nanoparticles. The approach was demonstrated both for surfaces possessing either a uniform particle density or a gradient in particle density. In the latter case samples with simultaneous, orthogonal gradients in both particle size and density were obtained. A combination of the bipolar approach with rapid image analysis was also evaluated as a method for corrosion screening, using quantitative analysis of gradients in pitting corrosion damage on stainless steels in HCl as a model system. The factors affecting gradient formation and the initiation of corrosion were thoroughly investigated by the use of a scanning droplet cell (SDC) technique and hard x-ray photoelectron spectroscopy (HAXPES). The ability to screen arrays of different materials for corrosion properties was also investigated, and demonstrated for stainless steel and Ti-Al alloys with pre-formed compositional gradients. The technique shows much promise for further studies and for high throughput corrosion screening applications.
252

Investigation of gold nanoparticle accumulation kinetics for effective cancer targeting

Park, Jaesook 09 November 2010 (has links)
Gold nanoparticles (GNP) have been widely used as optical imaging and photothermal therapy agents due to their biocompatibility, simplicity of conjugation chemistry, optical tunability and efficient light conversion to heat. A number of in vitro and in vivo studies have demonstrated that they can be used as effective thermal therapy and imaging contrast agents to treat and diagnose cancer. As clinical applications of GNPs for cancer imaging and therapy have gained interest, efforts for understanding their accumulation kinetics has become more important. Given the recent demonstration of intrinsic two-photon induced photoluminescence (TPIP) of gold nanoshells (GNSs) and gold nanorods (GNRs), TPIP imaging is an efficient tool for investigating the microscopic distribution of the GNPs at intra-organ level. The following work explores these GNPs’ physical and optical properties for effective use of GNPs in TPIP imaging and examines the feasibility of using intrinsic TPIP imaging to investigate GNP’s biodistribution in bulk tumors and thin tissue slices processed for standard histology. Our results showed that GNPs yield a strong TPIP signal, and we found that the direct luminescence-based contrast imaging of GNPs can image both GNPs and nuclei, cytoplasm or vasculature simultaneously. Also, we present the effect of GNP morphology on their distribution within organs. Collected images showed that GNPs had a heterogeneous distribution with higher accumulation at the tumor periphery. However, GNRs had deeper penetration into tumor than GNRs due to their shape and size. In addition, GNPs were observed in unique patterns close to vasculature. Finally, we introduce single- and multiple-dose administrations of GNPs as a way of increasing GNP accumulation in tumor. Our results show that multiple dosing can increase GNP accumulation in tumor 1.6 to 2 times more than single dosing. Histological analysis also demonstrated that there were no signs of acute toxicity in tumor, liver and spleen excised from the mice receiving 1 injection, 5 injections of GNPs and trehalose injection. / text
253

Switching mechanisms, electrical characterisation and fabrication of nanoparticle based non-volatile polymer memory devices

Prime, Dominic Charles January 2010 (has links)
Polymer and organic electronic memory devices offer the potential for cheap, simple memories that could compete across the whole spectrum of digital memories, from low cost, low performance applications, up to universal memories capable of replacing all current market leading technologies, such as hard disc drives, random access memories and Flash memories. Polymer memory devices (PMDs) are simple, two terminal metal-insulator-metal (MIM) bistable devices that can exist in two distinct conductivity states, with each state being induced by applying different voltages across the device terminals. Currently there are many unknowns and much ambiguity concerning the working mechanisms behind many of these PMDs, which is impeding their development. This research explores some of these many unanswered questions and presents new experimental data concerning their operation. One prevalent theory for the conductivity change is based on charging and charge trapping of nanoparticles and other species contained in the PMD. The work in this research experimentally shows that gold nanoparticle charging is possible in these devices and in certain cases offers an explanation of the working mechanism. However, experimental evidence presented in this research, shows that in many reported devices the switching mechanism is more likely to be related to electrode effects, or a breakdown mechanism in the polymer layer. Gold nanoparticle charging via electrostatic force microscopy (EFM) was demonstrated, using a novel device structure involving depositing gold nanoparticles between lateral electrodes. This allowed the gold nanoparticles themselves to be imaged, rather than the nanoparticle loaded insulating films, which have previously been investigated. This method offers the advantages of being able to see the charging effects of nanoparticles without any influence from the insulating matrix and also allows charging voltages to be applied via the electrodes, permitting EFM images to capture the charging information in near real-time. Device characteristics of gold nanoparticle based PMDs are presented, and assessed for use under different scenarios. Configurations of memory devices based on metal-insulator-semiconductor (MIS) structures have also been demonstrated. Simple interface circuitry is presented which is capable of performing read, write and erase functions to multiple memory cells on a substrate. Electrical properties of polystyrene thin films in the nanometre thickness range are reported for the first time, with insulator trapped charges found to be present in comparable levels to those in silicon dioxide insulating films. The dielectric breakdown strength of the films was found to be significantly higher than bulk material testing would suggest, with a maximum dielectric strength of 4.7 MV•cm-1 found, compared with the manufacturers bulk value of 0.2 – 0.8 MV•cm-1. Conduction mechanisms in polystyrene were investigated with the dominant conduction mechanism found to be Schottky emission.
254

Studium D-A a pi-pi interakcí a jejich využití při samoskladbě / The D-A and pi-pi interactions and their use in self-assembly

Rejchrtová, Blanka January 2014 (has links)
The D-A and π-π Interactions and Their Use in Self-Assembly Due to their well-defined shape, size and properties gold nanoparticles represent an advantageous platform for the study of non-covalent interactions between ligands anchored to their surface both in solution and in monolayers or thin films. The aim of this thesis was the synthesis of ligands for gold nanoparticles bearing an anchoring group at one end and a planar π-electron rich pyrene unit at the other. Six structurally variable ligands were prepared differing in the pyrene substitution pattern and the spacer between the aromatic part and the acetylated thiol function. Furthermore, a synthetic pathway leading to extended π-electron systems (both electron rich and electron poor) such as hexabenzocoronene derivatives and its fragments was explored. The key steps in the synthesis of these compounds are the cyclization reactions of alkynes leading to polycyclic intermediates and their ensuing cyclodehydrogenation (Scholl reaction). All of the prepared ligands and their intermediates were characterized by spectroscopic methods. The structure of the key hexakis(pentafluorosulfanyl-phenyl)benzene was confirmed by single crystal X-ray crystallography. The prepared ligands bearing a pyrene unit were deacetylated and anchored to the surface of...
255

Propriétés optiques effectives de films composites de polymère et de nanoparticules d’or / Effective optical properties of polymer - gold nanoparticle composite films

Vieaud, Julien 14 November 2011 (has links)
Nous étudions, par ellipsométrie spectroscopique, les propriétés optiques dans le domaine de l'UV-Visible-Infrarouge de films composites constitués de polymère et de nanoparticules d'or. Nous étudions la relation entre ces mesures et la structure des nanocomposites, que nous étudions par microscopie à force atomique en particulier. Nous distinguons l’analyse de films épais (tri-dimensionnels) et minces (quasi-bidimensionnels). Dans les deux cas, nous confrontons les résultats expérimentaux à des modèles théoriques de milieux effectifs dérivés de Maxwell-Garnett, en particulier. / By spectroscopic ellipsometry, we study the optical properties in the range of UV-Visible-Infrared of composites films made of polymer and gold nanoparticles. We study the relation between these measurement and the structure of the nanocomposites, that we study by atomic force microscopy in particular. We distinguish the analysis of thicks films (tridimensionals) and thins (quasi-bidimensionals). In both of case, we confronte these experimentals results to the theoric models of effectives medium derivated for Maxwell-Garnett in particular.
256

Quantification des espèces radicalaires produites en présence de nanoparticules d’or soumises à un rayonnement ionisant / Quantification of the radicals’ species produced in the presence of gold nanoparticles submitted to ionizing radiation

Gilles, Manon 06 July 2015 (has links)
Afin d’améliorer les traitements par radiothérapie, des radiosensibilisateurs tels que les nanoparticules d’or (NPo) sont étudiés. Mais leur translation en clinique nécessite une bonne compréhension des phénomènes en jeu. Si l’effet radiosensibilisateur a bien été confirmé sur des cibles biologiques (ADN, cellules et in vivo) et si les radicaux hydroxyle ont souvent été proposés comme intermédiaires, aucune preuve claire n’a encore été apportée. Ce travail avait pour premier objectif d’élaborer un protocole de « référence » afin de quantifier les radicaux hydroxyle et les électrons produits par les NPo en interaction avec un rayonnement ionisant. Cette étude a mis en évidence des productions massives de ces deux espèces pour des NPo non-fonctionnalisées. De plus, l'étude de différents paramètres, tels que la quantité de dioxygène en solution ou le rayonnement incident, nous a conduits à proposer un nouveau mécanisme permettant de rendre compte de nos résultats. Néanmoins, l'application biologique des NPo ne peut être envisagée que si ces nano-objets sont fonctionnalisés afin de les rendre furtifs et de les adresser spécifiquement à la tumeur. Après synthèse et caractérisation poussée de différents types de NPo fonctionnalisées, nous avons comparé la production de radicaux hydroxyle avec la dégradation d’une cible biologique, l'ADN, et mis en évidence l'impact significatif de la fonctionnalisation sur l'effet radiosensibilisateur. Ainsi, cette étude apporte des informations essentielles en vue de l’optimisation de la conception des NPo les plus efficaces pour la radiosensibilisation, une première étape vers leur application radiothérapeutique. / To improve radiotherapy efficiency, radiosensitizers such as gold nanoparticles (GNP) are developed. But to translate them to clinics, a good knowledge of the processes at stage is needed. GNP radiosensitizing effect was well-confirmed on biological targets (DNA, cells and in vivo) and hydroxyl radicals are often proposed to be key intermediates, but no clear evidence has been given yet. In this work, we first developed a ‘reference’ protocol to quantify hydroxyl radicals and electrons produced by GNP in their interaction with ionizing radiation. These investigations reveal a massive production of both species for non-functionalized GNP. Moreover the study of various parameters such as the concentration of dissolved dioxygen or the energy of the incident radiation leads us to propose a new mechanism on the origin of the radiosensitizing effect. Nevertheless, biological applications of GNP can only be considered if the nano-objects are functionalized to make them furtive, address them or deliver medicines to the tumor. After synthesis and characterization of different functionalized GNP, we compared hydroxyl radicals production with the damages induced on DNA and highlighted a significant impact of functionalization on the radiosensitizing effect. Finally, this work gives valuable information for the design of the most efficient GNP for radiotherapy which is a first step towards their medical application.
257

Produção de nanopartículas de Au induzida por pulsos laser de femtossegundos formatados / Gold nanoparticles production induced by shaped femtosecond laser pulses

Ferreira, Paulo Henrique Dias 27 October 2011 (has links)
Neste trabalho investigamos a dinâmica de formação de nanopartículas de Au por pulsos de femtossegundos formatados (800 nm, 30 fs, 1 kHz e 2 mJ), induzida pela ionização da molécula de quitosana. Inicialmente desenvolvemos um sistema de formatação de pulsos ultracurtos que faz uso de um modulador espacial de luz, constituído por um arranjo linear de cristais líquidos, com o qual somos capazes de impor distintas modulações de fase ao pulso laser. Para monitorar o processo de produção de nanopartículas, montamos um sistema de excitação (pulsos de femtossegundos) e prova (luz branca), o qual permite a observação em tempo real do aparecimento da banda de plásmon e, consequentemente, da dinâmica de formação das nanopartículas. Resultados obtidos para pulsos não formatados (limitados por Transformada de Fourier) demonstraram que a formação de nanopartículas deve-se à ionização não linear da quitosana, a qual está relacionada à oxidação do grupo hidroxila para o grupo carbonila. Medidas de microscopia eletrônica de transmissão forneceram os tamanhos (entre 20 e 100 nm) e formatos (esferas, pirâmides, hexágonos, bastões, etc) das nanopartículas geradas. Ainda, nossos resultados revelaram que esta ionização é iniciada por absorção multifotônica, mais especificamente por absorção de 4 fótons. Utilizando pulsos formatados com fase espectrais constante, degrau e cossenoidal com diferentes frequências, investigamos a influência destes na formação de nanopartículas. Concluímos que os pulsos mais longos são mais favoráveis ao processo de ionização, e consequente redução dos íons de Au para a formação de nanopartículas metálicas. Este comportamento se deve, provavelmente, à redistribuição da energia absorvida para os modos vibracionais, o que é mais provável para pulsos mais longos. Assim, o método apresentado pode abrir novas maneiras para a formação de nanopartículas de metálicas, as quais podem ser mais exploradas dos pontos de vista aplicado e fundamental. / In this work we have studied the synthesis of Au nanoparticles using shaped ultrashort pulses (800 nm, 30 fs, 1 kHz and 2 mJ), induced by the ionization of the chitosan. Initially we developed a pulse shaping setup that uses a spatial light modulator (liquid crystals array), with which we are able to impose distinct phase mask to the laser pulse. In order to monitor the nanoparticles production process, we used a pump-probe system, consisting of femtosecond pulses (pump) and white light (probe), which allows the observation of the plasmon band enhancement and hence the nanoparticles formation dynamics. The results obtained by Fourier Transform limited pulses have shown that the nanoparticles formation is due to the nonlinear ionization of chitosan, which is related to hydroxyl group oxidation to the carbonyl group. Transmission electron microscopy measurements provided the sizes (20-100 nm) and shapes (spheres, pyramids, hexagons, rods, etc.) of the produced nanoparticles. Moreover, our results revealed that ionization is initiated by multiphoton absorption, more specifically by four photons absorption. Using pulses shaped with constant, step and cossenoidal (with different frequencies) spectral phase masks, we investigated their influence in the nanoparticles formation. We conclude that longer pulses are more favorable to the ionization process and, consequently, to the gold ions reduction for the synthesis of the metallic nanoparticles. This behavior is probably due to the redistribution of the absorbed energy to the vibrational modes, which is more likely for longer pulses. Therefore, the approach presented here can open new ways to produce metallic nanoparticles, which can be further explored from applied and fundamental points of view.
258

Estudo espectroscópico de anticorpos empregando-se superfícies SERS-ativas visando o desenvolvimento de imunossensores / Spectroscopic study of antibodies employing SERS-active surfaces for the development of immunosensors

Almeida, Raquel Mariano de 15 April 2016 (has links)
Este estudo empregou anticorpos que podem ser peças chaves no eventual desenvolvimento de imunossensores, devido as suas características de seletividade e consequente determinação de espécies de interesse em análises clínicas, ambiental, saúde publica, entre outros. Para isto, foram feitos estudos de espectros Raman e SERS de anticorpos inteiros e/ou fragmentados (IgG humana, anti-IgG humana (H+L) e anti-IgG humana (Fab2)). Com isto, foram conhecidos os principais modos vibracionais destas biomoléculas que são úteis para a proposta de se construir imunossensores. Ambas as técnicas fornecem informações a respeito da estrutura secundária de proteínas. Quando há a imobilização dessas biomoléculas sobre superfícies SERS-ativas, é possível determinar a sua orientação. Considerando-se que na técnica SERS existe a possibilidade de se detectar uma molécula, por meio de hot spots, é importante que as imunoglobulinas estejam sem impurezas como, por exemplo, a albumina e transferrina no caso de anticorpos provenientes do soro humano. Assim, foram feitos experimentos de purificação dos anticorpos por meio de colunas de afinidade contendo proteína A, G ou uma mistura de A e G imobilizadas e, também, separação baseada no ponto isoelétrico. Testou-se a capacidade de ligação (quimissorção) de IgG humana ou de seus fragmentos F(ab)\' sobre superfícies de ouro por meio da técnica QCM-D. Para o estudo de superfícies SERS-ativas foram sintetizadas nanopartículas de ouro (NP-Au), com a aquisição de espectros de extinção no UV-Vis e obtenção de imagens MEV para caracterizá-las. Também, foram feitas variações no preparo de nanocubos de ouro (NC-Au) para obtenção de nanobastões de ouro (NB-Au), tendo-se em vista que estruturas com pontas favorecem a intensificação do sinal Raman em superfícies SERS-ativas. Por fim, considerando-se a existência de diversas ligações S-S, principalmente na região denominada dobradiça, no espectro SERS de IgGh diluída e do fragmento F(ab)\' constatou-se o surgimento de uma banda característica de C-S em 679 cm-1. Por isso, foi feita uma proposta da possível orientação desses anticorpos não fragmentados para que assumissem uma orientação sobre as superfícies SERS-ativas com características semelhantes às dos fragmentos F(ab)\'. / This study used antibodies that can be key elements in the possible evelopment of immunosensors, due to its selectivity and the consequent determination of species of interest in clinical analysis, environmental, public health, among others. For this, Raman and SERS spectra studies were made of whole and/or fragmented antibodies (human IgG, anti-human IgG (H + L) and anti-human IgG (Fab2)). With this, it were known the main vibrational modes of these biomolecules, useful for the proposal to assemble immunosensors. Both techniques provide information on the secondary structure of proteins. When these biomolecules are immobilized on SERS-active surfaces, it is possible to determine their orientation. Considering that, in the SERS technique, it is possible to detect a molecule through hot spots, it is important that the immunoglobulins are free of impurities, such as albumin and transferrin in the case of antibodies from human serum. Thus, purification experiments of antibodies were made via affinity columns containing protein A, G or a mixture of A and G immobilized and also separation based on isoelectric point. It was tested the binding capacity (chemisorption) of human IgG or its F(ab)\' on gold surfaces by means of QCM-D technique. For the study of SERS-active surfaces of gold nanoparticles were synthesized (Au-NP), with the acquisition of extinction spectra in the UV-Vis and obtaining SEM images to characterize them. Also, changes were made in the preparation of nanocubes gold (Au-NC) to obtain gold nanorods (Au-NR), having in view that ends with structures favor the enhancement of Raman signal on SERS-active surfaces. Finally, considering the existence of various S-S links, particularly in the region called hinge, in the SERS spectrum of diluted hIgG and F(ab)\', it was found the display of a characteristic band C-S 679 cm-1. Therefore, a proposal was made about the possible direction of these non-fragmented antibodies to assume an orientation on the SERS-active surfaces with similar characteristics to the F(ab)\'
259

Desenvolvimento de nanopartículas metal-proteína para a entrega de DNA em estudos de terapia e vacinação gênicas. / Development of metal-protein nanoparticles for DNA delivery in gene therapy and vaccination studies.

Palma, Matheus Mlot 08 May 2017 (has links)
Um problema recorrente no desenvolvimento de vacinas de DNA e terapia gênica utilizando vetores não virais é a baixa eficiência de transfecção gênica. Isso ocorre devido às diversas barreiras físicas, enzimáticas e difusionais que o DNA precisa superar para chegar ao núcleo das células. Neste trabalho tem-se por objetivo o desenvolvimento de novos vetores não virais de entrega gênica, formados por DNA plasmidial (pDNA), proteínas (protamina ou T-Rp3) e nanopartículas de ouro (NPAu) na forma de complexos ternários. Para tal, NPAu\'s foram sintetizadas por redução com citrato de sódio, apresentando diâmetros entre 20,3 e 57,3 nm e potencial zeta entre -69,0 e +43,3 mV, dependendo das condições de síntese, a saber, das quantidades de citrato de sódio adicionadas e da ordem de adição dos reagentes. Em seguida, vetores compostos por pDNA-protamina/T-Rp3-NPAu foram formados, transfectados em células HeLa cultivadas in vitro, e a atividade da enzima repórter luciferase foi medida. Deste modo, a partir de variações em proporção mássica e tamanho de nanopartículas, foi possível obter complexos utilizando protamina e ouro com uma eficiência de transfecção 33 vezes melhor do que transfecções utilizando apenas protamina. Por outro lado, complexos contendo T-Rp3 e ouro se mostraram ainda mais eficazes na entrega, apresentando níveis de transfecção próximos ao do reagente comercial Lipofectamina. Ensaios de transfecção utilizando a droga nocodazol indicaram a importância dos microtúbulos no mecanismo de entrega gênica, e ensaios com a droga cloroquina evidenciaram que as nanopartículas de ouro atuam de maneira diferenciada no escape endossomal dos vetores não virais utilizados. Visando relacionar características físico-químicas com a eficiência de transfecção, alguns destes complexos foram caracterizados por espalhamento dinâmico de luz, em que complexos com protamina apresentaram tamanhos entre 116 e 363 nm e complexos com T-Rp3 apresentaram entre 135 e 307 nm e potenciais zeta entre +7,3 e +22,5 mV e +10,6 e +27,2 mV, respectivamente, dependendo das características das NPAu\'s. / A recurrent problem in the development of DNA vaccines and gene therapy using non-viral vectors is the low efficiency of transfection. That is due to the many physical, enzymatic and diffusional barriers that DNA must overcome to reach the cell nucleus. This work aims to develop novel non-viral vectors based on plasmid DNA (pDNA), proteins (protamine or recombinant T-Rp3) and gold nanoparticles (AuNP) as ternary complexes. For such, AuNP\'s were first synthesized via sodium citrate reduction, with diameters varying from 20,3 to 57,3 nm and zeta potentials between -69,0 and +43,3 mV, depending on synthesis conditions, changing the quantities of sodium citrate added and the order of addition of reagents. Vectors formed by pDNA-protamine/T-Rp3-AuNP were then formed, transfected and luciferase activity was measured. Thus, from variations on mass ratios and gold nanoparticle sizes, it was possible to obtain complexes with protamine and gold with a transfection efficiency 33 times higher than analog complexes using only protamine. Also, complexes containing T-Rp3 and gold showed an even higher delivery efficiency, with transfection efficiency close to Lipofectamine. Assays using nocodazole indicated the importance of microtubule in the gene delivery process and, whereas assays with chloroquine showed that gold nanoparticles act in a different way over endossomal escape of used non-viral vectors. Finally, some of these complexes were characterized with dynamic light scattering. Complexes with protamine were within the size ragne of 116 to 363 nm and complexes with T-Rp3 were within the size range of 135 to 307 nm. The zeta potential varied from +7,3 to +22,5 mV and from +10,6 to +27,2 mV, respectively, depending on the gold nanoparticles used.
260

Síntese de nanopartículas de ouro com forma e tamanho controlados utilizando glicerol como um agente de redução e estabilização ecológico e de baixo custo / Synthesis of Shape and Size controlled gold nanoparticles using glycerol as a low-cost and environmental friendly reducing and stabilizing agent

Parveen, Rashida 26 June 2017 (has links)
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.

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