Plasmonic Laser Nanosurgery (PLN) is a novel photodisruption technique that exploits the large enhancement of ultrafast laser pulses in the near-field of gold nanoparticles for the nanoscale manipulation of biological structures. Excitation of surface plasmons on spherical nanoparticles by pulsed irradiation provides a platform for the confinement of photoactivated processes, while functionalized nanoparticle targeting methods provide the highest level of therapeutic selectivity. In this dissertation, we demonstrate and characterize the in vitro plasmonic optoporation of MDA-MB-468 human epithelial breast cancer cells labeled with plasmonic gold nanoparticles using NIR, femtosecond laser pulses. Using a 10 kDa FITC-Dextran probe dye, we find that the PLN can optoporate nanoparticle-labeled cellular membranes at fluences down to just a few mJ/cm², providing a 50-fold reduction in pulse energy necessary to induce membrane dysfunction as compared with unlabeled cells. Limited membrane dysfunction was found to lead to transient optoporation of cells as a possible transfection method, while more extensive, non-recoverable membrane dysfunction lead to cellular death as a possible plasmonic treatment of malicious cells. In the first regime, we found a maximum optoporation efficiency of approximately 31% ± 5.4% with 2 to 2.5 mW laser light having 80 MHz repetition rate. In the second regime, we were able to necrotically kill greater than 90% of irradiated cells with as little as 5 mW average power. We found that particle aggregation along the cellular surface is crucial for the success of PLN. High particle loadings were required, suggesting that particle aggregates provide large enhancements, leading to reduced PLN threshold energies. We provide experimental evidence suggesting photodisruption with ultra-low energy pulses is directly dependent upon the emission of electrons from the particle surface, which seed the formation of free radicals in the surrounding water. These free radicals mediate membrane dysfunction by polyunsaturated lipid and protein peroxidation. / text

No / We report the structure of the electrical double layer, determined from molecular dynamics simulations, for a range of saline solutions (NaCl, KCl, MgCl2 and CaCl2) at both 0.16 and 0.60 mol kg(-1) on different facets of the gold and silver aqueous interfaces. We consider the Au/Ag(111), native Au/Ag(100) and reconstructed Au(100)(5×1) facets. For a given combination of metallic surface and facet, some variations in density profile are apparent across the different cations in solution, with the corresponding chloride counterion profiles remaining broadly invariant. All density profiles at the higher concentration are predicted to be very similar to their low-concentration counterparts. We find that each electrolyte responds differently to the different metallic surface and facets, particularly those of the divalent metal ions. Our findings reveal marked differences in density profiles between facets for a given metallic interface for both Mg(2+) and Ca(2+), with Na(+) and K(+) showing much less distinction. Mg(2+) was the only ion for which we find evidence of materials-dependent differences in interfacial solution structuring between the Ag and Au. / Veski, Air Force Office for Scientific Research grant #FA9550-12-1-0226

No description available.

The fascinating physical properties that arise in materials limited to dimensions of 1-100 nm have gained noteworthy interest from the scientific community. Accordingly, there has been a lot of attention paid to the synthesis of discrete nanoparticles (NPs) and they are being investigated for a range of advanced technologies. Nonetheless, efficient use of nanomaterials in device applications require them to be assembled into solid state macro-structures while retaining their unique, nanoparticulate properties. To date, most commonly investigated assembling techniques include: covalent coupling of NPs surface groups, control evaporation of the solvent to produce ordered supercrystals or non-ordered glassy films, and polymer or bimolecular mediated self-assembly. However, in each of these cases, the interactions among discrete NPs are mediated by intervening ligands, the presence of which are detrimental for efficient electronic transport and interparticle coupling that limit performance in optoelectronic,electro-catalytic, and chemical sensor studies. Thus, novel and efficient strategies that can be predictably manipulated for direct, self-supported assembly of NPs are of critical need. A method that has proved useful to construct direct interfacial linkages of colloidal NPs is the sol-gel technique.Oxidative removal of surfactant ligands has been shown to produce self-supported NP monoliths that in most cases retain the physical properties of primary NPs.The ability to create direct interfacial bonds contributes to enhanced electrical and thermal transport as well as tunable interparticle interactions, expanding the potential range of NP technologies. During oxidation, low coordinated active sites are produced on the NP surface that interacts with a nearby NP to reduce the surface energy. The formed active sites are highly reactive allowing the NPs to establish direct interfacial linkages, polymerize into low dimensional clusters, and consequently highly porous superstructures that augment the unique, nanoparticulate properties. An added advantage of this chemistry is the ability to couple chemically similar or dissimilar systems with the potential to achieve novel/tunable physical properties. In this dissertation, application of sol-gel chemistry in efficient integration of similar and dissimilar nanoscale materials will be discussed with an aim of achieving improved optoelectronic and electro-catalytic properties. Hybrid nanomaterials composed of metal-semiconductor components exhibit unique properties in comparison to their individual counterparts, making them of great interest for optoelectronic technologies. The direct cross-linking of NPs via sol-gel chemistry provides a versatile route to tune interfacial interactions in a manner that has not been thoroughly investigated. Thus, the first part of the dissertation will illustrate the synthesis of CdSe/Ag hetero-nanostructures (aerogels) via oxidation induced self-assembly of thiol-coated NPs and investigate the evolution of optical properties as a function of Ag composition. Two hybrid systems were investigated, where the first and second excitonic energies of CdSe were matched with plasmonic energy of Au and Ag NPs. The optical properties of the CdSe/Ag hybrids were systematically examined through UV-visible, photoluminescence, and time resolved photoluminescence spectroscopy. A new emission (640 nm) from CdSe/Ag aerogels was emerged at Ag loading as low as 0.27 % whereas absorption band tailing and PL quenching effects were observed at higher Ag and Au loading, respectively. The TRPL decay time of the new emission (~600 ns) is markedly different from those of the band-edge (1.83 ± 0.03 ns) and trap state (1190 ± 120 ns) emission maxima of phase pure CdSe, supporting the existence of alternate radiative relaxation pathways in sol-gel derived CdSe/Ag hybrids. An added benefit of newly developed sol-gel chemistry is the potential to produce porous, conducting nanoarchitectures that provide a facile pathway for efficient transfer of charge carriers and small molecules. Thus, aerogels composed entirely of noble metal NPs are expected to exhibit high electrical conductivity making them promising for electrocatalysis. Thus, the second part of the dissertation will describe the extension of NP condensation strategy for the fabrication of ternary noble metal (Au/Ag/Pd, Au/Ag/Pt) aerogels for electro-oxidation of alcohols. The precursor alloy NPs were produced via stepwise galvanic replacement of thiol-coated Ag NPs. The resultant alloy NPs were self-assembled into large, free-standing aerogels that exhibit direct interparticle connectivity, high surface area (282 – 98 m2/g) and mesoporosity (2 – 50 nm) via controlled oxidation of the surfactant ligands. The gelation kinetics has been controlled by varying the oxidant/surfactant molar ratio that governs the dealloying of Ag from ternary superstructures with in-situ generated HNO3. The monolithic Au/Ag/Pd alloy aerogels exhibit higher catalytic activity and durability compared to the discrete alloy NPs (~ 20-30 times) and commercial Pd/C catalyst (2-3 times). On the other hand, Au/Ag/Pt alloy aerogels showed excellent stability at higher concentration of methanol (12 M) during electro-oxidation studies, suggesting its superior electro-catalytic activity. The synergistic effect of tri-metallic alloy mitigates the catalyst poisoning and increases the stability and durability whereas the self-supported superstructure with direct interparticle connectivity, high surface area and porosity offers a facile conduit for molecular and electronic transport, enabling the ternary aerogels an efficient electro-catalyst.

This dissertation is directed towards the fundamental understanding of the controlled synthesis of noble-metal (silver, gold, and palladium) and metal oxide (manganese and copper oxide) nanostructures as well as their applications in heterogeneous and plasmonic catalysis. In the first part of this work (Section 1), we provided a general background concerning the science of controlled nanomaterials, their syntheses, properties, and applications in catalysis and plasmonic catalysis. Then, we describe and developed a series of protocols for the synthesis of these nanomaterials with controlled sizes and structures (spheres, cubes, rods, shells, flowers, dendrites, and tadpoles), mainly focusing on the mechanistic understanding of their formation and how physical and chemical parameters (size, shape, composition, surface morphology) may influence/modify their catalytic properties (Sections 2 and 3). In Section 4, we turned our attention for the design of simple protocols for the synthesis of advanced nanomaterials that are interesting for green catalytic transformations applications. In this case, we envisioned the use of MnO2-Au nanomaterials (nanowires and nanoflowers) displaying several properties (unique pore structure, high surface area, ultrasmall Au NPs at the surface, high concentration of oxygen vacancies and Auδ+ species, strong metal-support interactions, and uniform shapes and sizes) that are desirable for catalyzing a series of green oxidation reactions in mild conditions (low temperatures and molecular oxygen or atmospheric air as the oxidants). In Section 5, we have demonstrated that catalysis and optical properties can be merged together to improve catalytic processes, the so called-plasmonic catalysis. This allowed us the use of visible light as the energy input to drive chemical transformations in mild conditions and then provide new insights regarding the various factors that affect SPR-mediated catalytic activities in plasmonic nanostructures. Finally, in Section 6, we focused our attention on how important is to introduce both nanoscience and the synthesis/characterization of nanomaterials having controlled physicochemical features to undergraduate students. Specifically, we have described simple laboratory experiments for the synthesis of nanomaterials (gold nanospheres and Cu(OH)2/CuO nanowires) displaying uniform sizes and shapes in order to investigate and explain their optical properties, catalytic activities and formation mechanisms. / Não consta resumo na publicação.

This dissertation is directed towards the fundamental understanding of the controlled synthesis of noble-metal (silver, gold, and palladium) and metal oxide (manganese and copper oxide) nanostructures as well as their applications in heterogeneous and plasmonic catalysis. In the first part of this work (Section 1), we provided a general background concerning the science of controlled nanomaterials, their syntheses, properties, and applications in catalysis and plasmonic catalysis. Then, we describe and developed a series of protocols for the synthesis of these nanomaterials with controlled sizes and structures (spheres, cubes, rods, shells, flowers, dendrites, and tadpoles), mainly focusing on the mechanistic understanding of their formation and how physical and chemical parameters (size, shape, composition, surface morphology) may influence/modify their catalytic properties (Sections 2 and 3). In Section 4, we turned our attention for the design of simple protocols for the synthesis of advanced nanomaterials that are interesting for green catalytic transformations applications. In this case, we envisioned the use of MnO2-Au nanomaterials (nanowires and nanoflowers) displaying several properties (unique pore structure, high surface area, ultrasmall Au NPs at the surface, high concentration of oxygen vacancies and Auδ+ species, strong metal-support interactions, and uniform shapes and sizes) that are desirable for catalyzing a series of green oxidation reactions in mild conditions (low temperatures and molecular oxygen or atmospheric air as the oxidants). In Section 5, we have demonstrated that catalysis and optical properties can be merged together to improve catalytic processes, the so called-plasmonic catalysis. This allowed us the use of visible light as the energy input to drive chemical transformations in mild conditions and then provide new insights regarding the various factors that affect SPR-mediated catalytic activities in plasmonic nanostructures. Finally, in Section 6, we focused our attention on how important is to introduce both nanoscience and the synthesis/characterization of nanomaterials having controlled physicochemical features to undergraduate students. Specifically, we have described simple laboratory experiments for the synthesis of nanomaterials (gold nanospheres and Cu(OH)2/CuO nanowires) displaying uniform sizes and shapes in order to investigate and explain their optical properties, catalytic activities and formation mechanisms. / Não consta resumo na publicação.

Orientador: Yoshitaka Gushikem / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T17:04:12Z (GMT). No. of bitstreams: 1 Fattori_Natalia_D.pdf: 3454511 bytes, checksum: 8b2aa591a45da1692fb09a098dea4e58 (MD5) Previous issue date: 2014 / Resumo: O presente trabalho descreve um método de preparação de nanopartículas metálicas suportadas em sílicas mesoporosas organofuncionalizadas. Dois diferentes substratos foram explorados: uma sílica mesoporosa constituída de uma estrutura porosa altamente ordenada e uniforme, composta de poros ou canais cilíndricos dispostos paralelamente e empacotados em arranjo hexagonal (SBA-15), e uma sílica mesoporosa caracterizada por uma rede desordenada de poros, de tamanho e forma variados, distribuídos e interconectados aleatoriamente ao longo da estrutura porosa (SMD). As duas matrizes tiveram suas superfícies quimicamente modificadas com dois diferentes agentes funcionalizantes constituídos de cátions orgânicos (R+Cl-) com propriedades de troca-iônica, derivados das moléculas 1-metilimidazol (Imi) e 4,4?-bipiridina (Bipy). Em ambos os casos, as propriedades íontrocadoras dos cátions orgânicos ancorados na superfície das sílicas permitem a retenção de ânions complexos de metais nobres ([AuCl4]-, [PtCl6]2- e [PdCl4]2-) confinados na estrutura porosa. Estas espécies foram convertidas in situ nas nanopartículas metálicas de interesse pela redução dos íons metálicos com agentes redutores adequados. As matrizes modificadas com o grupo funcional Imi foram utilizadas como suportes para a preparação e estabilização de nanopartículas metálicas (Au, Pt, Pd e ligas metálicas Au-Pt, Au-Pd e Pt-Pd). Já as matrizes modificadas com o grupo funcional Bipy foram utilizadas como suportes para o preparo de nanopartículas de ouro / Abstract: The present work describes a new method for preparing metal nanoparticles supported on organofuncionalized mesoporous silica. Two different substrates were used: a mesoporous silica constituted by a highly ordered and uniform porous framework, with parallel cylindrical pore channels packed in a hexagonal array (SBA-15), and a mesoporous silica characterized by a disordered porous framework, with non-uniform size and shape, distributed and interconnected randomly throughout the porous structure (SMD). Both substrates were chemically modified with two different functional groups constituted of organic cations (R+Cl-) with ion-exchange properties, derivative from the molecules 1-methylimidazole (Imi) and 4,4?-bipyridine (Bipy). In both cases, the ion-exchange properties of the cationic groups attached to the silica surface allows the retention of anionic noble metal complex ([AuCl4]-, [PtCl6]2- e [PdCl4]2-), confined within the porous structure. These species were converted in situ into metal nanoparticles by means of reduction of the metal ions with proper reducing agents. The substrates modified with the functional group Imi were used as supports for the preparation and stabilization of noble metal nanoparticles (Au, Pt, Pd and metal alloys Au-Pt, Au-Pd and Pd-Pt). The substrates modified with the functional group Bipy were used as supported for the preparation of gold nanoparticles / Doutorado / Quimica Inorganica / Doutor em Ciências

No description available.

<p> Ophiolites are generally regarded as fragments of ancient oceanic crust and upper mantle emplaced on the continents. Thetford Mines ophiolites probably formed in a marginal or back-arc basin by three separate but related igneous events. The first event involved the partial melting of a rising mantle diapir. The melt produced later underwent extensive fractional crystallization involving olivine, spinel, pyroxene and plagioclase to form a layered sequence of dunitic, pyroxenitic and gabbroic cumulate rocks. The residual magma fraction after this extensive fractional crystallization was later erupted as part of hypabyssal rocks and MgO, Cr and Ni poor lavas. During the second and third stages, the residual mantle material from the first episode of melting was remelted to produce melts from which low TiO2 lavas were formed. The low TiO2 lavas are also depleted in other incompatible elements such as Zr and Y which presumably were lost into the magma produced by the first stage melting of the mantle. The mantle residue after the multi-stage melting of the mantle is believed to be represented by the harzburgite occurring at the base of the ophiolite suite.</p> <p> The cumulates display wide variability in their major and trace as well as noble metal contents principally in response to fractional crystallization while the harzburgite displays uniform chemistry, compatible with its origin as a residue of extensive partial melting of the mantle. However, on the average, Thetford Mines plutonic rocks have similar noble metal contents to Mt. Albert pluton, Gaspe, but have higher PGE than the Troodos ophiolites. Thetford Mines rocks are also depleted in the noble metals in comparison to the stratiform layered complexes such as Bushveld and Stillwater. The volcanic rocks can be classified into three groups on the basis of their noble metal contents viz., i) low Ir, low Pd lavas, ii) low Ir, high Pd and iii) high Ir, high Pd lavas. These groups correspond to the lavas produced during the first, second and third igneous events respectively. The noble metal contents of the first group are similar to most ocean floor basalts while the third group lavas are comparable only to oceanic island and intraplate basalts.</p> <p> During fractional crystallization of the parental magma of the cumulates, Ir was strongly partitioned into early formed rocks such as the olivine-chromite cumulates while Pt and Pd were progressively enriched in the residual magma fraction. Au, however, was less sensitive to fractional crystallization than the PGE.</p> <p> After the formation of the ophiolites, the lavas and hypabyssal rocks were metamorphosed to greenschist facies by hydrothermal sea water, and the ultramafic rocks were serpentinized, first in the oceanic environment by sea water and later on the continent by meteoric water, Most of the major and trace elements were mobilized during the hydrothermal alteration of the lavas but the PGE were immobile. It is suggested that the redox potential of the hydrothermal solution was not high enough to oxidize the noble metals and so permit mobilization. Au, however, shows some degree of mobilization, and it is believed that some Au occurred along grain boundaries and was carried as particulate material (mechanically) by hydrothermal solution. The noble metals were only slightly mobilized during the continental serpentinization episode. Their inertness during the oceanic serpentinization episode is attributed to the reducing condition of the oceanic environment which prevented formation of soluble noble metal complex ions.</p> <p> Unlike many ophiolite occurrences, Thetford Mines rocks appear to have very little economic potential with respect to base and noble metals, principally because of lack of abundant sulfides to act as concentrators of the metals.</p> / Thesis / Doctor of Philosophy (PhD)

An extremely facile and novel method called spontaneous deposition, to deposit noble metal nanoparticles on a most stable form of carbon (C) i.e. diamond is presented. Nanometer sized particles of such metals as platinum (Pt), palladium (Pd), gold (Au), copper (Cu) and silver (Ag) could be deposited on boron-doped (B-doped) polycrystalline diamond films grown on silicon (Si) substrates, by simply immersing the diamond/Si sample in hydrofluoric acid (HF) solution containing ions of the corresponding metal. The electrons for the reduction of metal ions came from the Si back substrate. The diamond/Si interfacial ohmic contact was of paramount importance to the observation of the spontaneous deposition process. The metal/diamond (M/C) surfaces were investigated using Raman spectroscopy, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffractometry (XRD). The morphology (i.e. size and distribution) of metal nanoparticles deposits could be controlled by adjusting the metal ion concentration, HF concentration and deposition time. XRD data indicate the presence of textured and strained crystal lattices of Pd for different Pd/C morphologies, which seem to influence the electrocatalytic oxidation of formaldehyde (HCHO). The sensitivity of electrocatalytic reactions to surface crystal structure implies that M/C could be fabricated for specific electrocatalytic applications. The research also presents electroplating of Cu on ruthenium (Ru), which a priori is a promising barrier material for Cu interconnects in the sub 0.13 μm generation integrated circuits (ICs). Cu plates on Ru with over 90% efficiency. The electrochemical nucleation and growth studies using the potentiostatic current transient method showed a predominantly progressive nucleation of Cu on Ru. This was also supported by SEM imaging, which showed that continuous thin films of Cu (ca. 400 Å) with excellent conformity could be plated over Ru without dendrite formation. Scotch tape peel tests and SEM on Cu/Ru samples both at room temperature (RT) and after annealing at 800 oC, showed no sign of delamination of the Cu film from Ru indicating strong adhesion. XRD patterns from Cu/Ru samples at RT through 800 oC indicated Cu in its characteristic face centered cubic (fcc) form with (111) phase dominating. Most importantly no new XRD peak emerged, even after annealing to 800 oC showing Cu and Ru did not interact much. The excellent adhesion and lack of metallurgical interactions between Cu and Ru underscored the potential application of Ru as a new Cu diffusion barrier in the next generation ICs.