The clinical evaluation of people with possible myocardial infarction (MI) is often limited by atypical symptoms and inconclusive initial electrocardiograms. A recent consensus from the American College of Cardiology has redefined acute MI to include cardiac markers as central to diagnosis. To address this clinical need, a sensitive microfluidic surface-enhanced Raman spectroscopy (SERS) nanochannel-based optical device is being developed for ultimate use as a point-of-care device for the simultaneous measurement of MI blood biomarkers. The device can provide enhancements of the Raman signal of the analyte measured of up to 1013 using a mechanical aggregation technique at the interface of nanofluidic structures enabling repeatable SERS measurements. Specifically in this research iterations of a sensitive, low volume SERS platform technology were designed that provided quantitative information across a specific range. With the SERS platforms studied, not only were SERS enhancements of up to 1013 achieved but also imprecision values of less than 10% across the 10-50 pM range using a ratiometric approach and qualitative detection down to 100 aM was achieved. Beyond assessment of SERS substrates, assay designs were investigated and characterized including, label-free techniques and competitive immunoassay formats. Lastly, detecting the SERS signal of multiplexed reporter molecules was investigated. By identifying the analyte and assay constraints the design and optimization of future assays will be aided using this SERS platform technology.

The goal of current solid oxide fuel cell (SOFC) research is to design electrode materials and other system components that permit the fuel cell to be operated in the 400-700ºC range. Cell performance in this lower temperature range is limited by the oxygen reduction process at the SOFC cathode and by multiple contamination processes. The work presented demonstrates that Raman spectroscopy, a form of vibrational spectroscopy, can provide structural and compositional information complementary to that from traditional characterization methods. Initial experiments into the oxygen reduction mechanism on SOFC cathodes were unable to detect surface oxygen species on selected perovksite-based SOFC cathode materials. However, the Raman signal from the cathode surface was able to be enhanced by depositing silver or gold nanoparticles on the cathode, creating the so-called surface-enhanced Raman scattering (SERS) effect. The Raman sample chamber was also used to study two possible electrode contamination processes. First, the deposition of carbon on nickel and copper anodes was observed when exposed to different hydrocarbon fuel gases. Second, the poisoning of an SOFC cathode by chromium-containing vapor (usually generated by stainless steel SOFC system components) was monitored. Overall, Raman spectroscopy was shown to be useful in many areas crucial to the development of practical, cost-effective SOFCs. The techniques developed here could also be applied to other high temperature electrochemical and catalytic systems.

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper and copper-, based alloys for more than 40 years. It has been successfully employed for the, prevention of both atmospheric corrosion and particularly for the protection of, copper under immersed conditions. Whilst BTAH is an excellent inhibitor in alkaline, solution its efficiency drops off markedly as the pH decreases. It was hypothesized, that a possible way to increase surface adsorption and subsequent better inhibition, over a wide pH range might be through the preparation of derivatives, particularly, carboxybenzotriazoles and alkyl esters of these compounds. In this work the following techniques: weight loss measurements, potentiodynamic, polarisation, SERS spectroscopy, electrochemical impedance spectroscopy and, coulometry were employed to investigate the inhibition efficiency of 4- and 5-, carboxybenzotriazole and their alkyl ester for copper corrosion. Molecular modelling, was also investigated as a tool for inhibitor design. Studies on 4- and 5- carboxybenzotriazole (CBT) showed that the inhibition, efficiency for copper corrosion in aerated acidic sulphate solution of each isomer was, pH, concentration and time dependant. At lower pH the 5-isomer is the better, inhibitor and this behaviour continues at higher pH. The anti-tarnishing test showed, that whilst both isomers exhibited these properties, 5-CBT was once again the, superior inhibitor. It was found that a commercial mixture of the octyl esters of 4- and 5-, carboxybenzotriazole inhibits copper corrosion in sulphate environments open to air., The inhibition efficiency of the ester mixture at the lx10-4 M level (pH - 0) is 98%, which compares very favourably with that for BTAH (- 50%). With respect to other, alkyl esters of 4- and 5-carboxybezotriazole, hexyl, butyl and methyl, it was found, that all of these inlibited copper corrosion in sulphate environments open to air. In, each case the inhibition efficiency is concentration, pH and time dependent. Both, coupon tests and EIS measurements indicate that inhibition efficiency depends on the, length of the alkyl chain. At pH - 0 the inhibition efficiency decreased in the order, octyl &gthexyl &gtbutyl &gtmethyl. At higher pH (- 8) the order is reversed. At the 1x104, M level (pH - 0) the inhibition efficiency of each of the alkyl esters is equal to or, better than that for BTAH. At higher pH (- 8) the inhibition efficiency in each case is, reduced in comparison to BTAH. but is still good enough for practical use ( 2 75%)., The inhibitive behaviour of the alkyl esters at low pH can be attributed to, chemisorption through an azole nitrogen of the protonated alkyl esters. The, hydrocarbon chain is also physically adsorbed and the increase in physical adsorption, as the chain is lengthened accounts for the improved inhibition efficiency. Dry films formed by immersing copper in solutions of alkyl esters of, carboxybenzotriazole also inhibit copper corrosion in both strongly acidic (pH - 0), and near neutral (pH - S) sulphate corrodents. The inhibition efficiency depends on, the solvents used to dissolve the esters, solution temperature and immersion time., Aqueous coating solutions furnish the most protective films. Films formed by, CBTAH-BU, CBTAH-HE and CBTAH-OE are more protective than that formed by, BTAH. The inhibition efficiency of the alkyl ester film increases as the alkyl chain is, made longer. Molecular modeling showed that the optimum crude binding energy (Eblnd), between each protonated ester molecule and the surface varied linearly with the alkyl, chain length. The resulting linear correlation between IE% and E bind for compounds, that are structurally similar suggested that the crude binding energy of a single, molecule with copper may be used to predict the inhibition performance of other, compounds constituting a series.

The aim of this thesis was using surface-enhanced Raman scattering (SERS) microspectroscopy for the study of biomolecules and biological systems. The main probe molecule was cationic porphyrin H2TMPyP, however, other porphyrins, tryptophan and two lipids were also used. The sensitivity and reproducibility of several solid SERS substrates: (i) Au and Ag nanoparticles (NPs) immobilized via a bifunctional linker, (ii) AgNPs immobilized by drying, (iii) highly ordered Au and Ag film-over-nanosphere (FON) and (iv) Ag-coated insect wings were compared. On most of the solid substrates, the lowest detected H2TMPyP concentration was ~10-8 M. The highest sensitivity was provided by the dried drops of AgNPs/analyte mixture, where concentrations 1×10-10 M TMPyP, 1×10-5 M tryptophan, 2×10-7 M DSPC and 3×10-7 M DMTAP were detected. Nevertheless, the spectral reproducibility was decreased due to porphyrin metallation and perturbation of the lipid spectra in comparison to their Raman spectra from solution. The highest reproducibility was achieved by AuFON and Ag-coated insect wings. Finally, the AgNPs modified by PEG polymers were tested for intracellular application using HeLa cancer cells. Metallation of H2TMPyP served to probe the accessibility of PEG- AgNPs surface. The results proved that the accessibility...

Surface-Enhanced Raman Scattering (SERS) has the potential to be a rapid disease diagnostic platform. SERS is a well-known ultrasensitive, label-free method for the detection and identification of molecules at low concentrations. The Raman cross-sections are primarily enhanced by plasmonic effects for molecules close to (< 5 nm) the surface of nanostructured metal substrates. Due to the unique Raman vibration features that provide molecular signatures, we have shown that SERS can provide a rapid (< one hour), label-free, sensitive and specific diagnosis for a number of diseases. This work demonstrates the capability of SERS to be an effective optical diagnostic approach, in particular, for bacterial infectious diseases such as urinary tract infections (UTI) and sexually transmitted diseases (STD), and cancer cell identification. More specifically, this work demonstrates the ability of SERS to distinguish different vegetative bacterial cells with species and strain specificity based on their intrinsic SERS molecular signatures. With the exception of C. trachomatis - the causative agent of chlamydia - whose SERS molecular signatures are found to be aggregated proteins on the cell membrane, all bacterial SERS molecular signatures are due to purine molecules resulting from nucleic acid metabolism as part of the rapid onset of the starvation response of these pathogens. The differences in relative contribution of different purine metabolites for each bacterium gives rise to the SERS strain and species specificity. The ability of SERS to distinguish cancer and normal cells grown in vitro based on changes of SERS spectral feature as a function of time after sample processing is also demonstrated. Furthermore, the difference of spectral features on the gold and silver SERS substrate of the same bacteria can be used as additional attribute for identification. This work demonstrate the potential of SERS platform to provide antibiotic-specific diagnostics in clinical settings within one hour when combined with a portable Raman microscopy instrument, an effective enrichment procedure, multivariate data analysis and an expendable SERS reference library with drug-susceptibility profile for each bacterial strain determined a priori, as well as the ability of SERS platform as a powerful bioanalytical probe for learning about near cell membrane biochemical processes.

Thin metal films have attracted much interest because they provide a way to produce surface plasmon resonance (SPR) in the Kretschmann configuration. This technique is a very sensitive for determining small changes at the interface between a metallic layer and a dielectric medium, and the metals generally used are silver and gold once their surface plasmon resonances are located in the visible range. Thin films of gold, due their stability and diversity applications, have been extensively studied by electrochemistry, surface enhanced Raman spectroscopy (SERS) and techniques of Microscopic such as AFM and STM. The Raman technique has been used to the analysis of organics compounds in determined system. However, in very low concentration levels is inefficient due to weak signal or interference from noise. A developed method to markedly increase the signal of a species presented at many levels is the SERS. One of the major considerations for the formation of a SERS-active surface is surface roughness, and this has been realized by various ways. In the present work, we analyzed the efects of various oxidation-reduction cycles (ORCs) on the surface of the thin films of gold using the techniques of cyclic voltammetry, microscopy, UV-Vis spectroscopy and SPR, which will be used to evaluate the efficiency of electrochemically modified substrates as SERS and SPR active. Initially, the film was cycling in a solution of H2SO4 to remove impurities from the surface. After this procedure, the 50 nm and 100 nm thick gold films, deposited on a glass substrate, were subjected to a series of ORCs in a solution of H2SO4 containing 0,005 M KCl electrolyte. As the number of ORCs is increased, the roughness of the film increased. We used techniques of microscopy, Spectroscopy UV-Vis, Resonance Plasmon Surface and Cyclic Voltammetry to characterize the surface of the film as a function of roughness. A “home − made” SPR system based on the configuration of Kretschmann was utilized for analyzed the changes provoked in surface film before and after the electrochemically modified. The medium size of the gold islands deposited was analyzed for Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM). This same metallic film, after passing for oxidation processes and reduction, was used to obtain a spectrum SER using an organic molecule the 2-thiouracil adsorbed on the surface of the film. The results observed for AFM, STM and cyclic voltammetry shows that surfaces electrochemically modified increase the roughness, and that the changes modified o depth of the signal SPR. These change provoked electrochemistry after various ORC improve significantly the Raman sign of molecules adsorbed on the surfaces of the metallic films. Finally, we conducted an evaluation of the roughness factor obtained through the techniques of AFM, STM and cyclic voltammetry. _______________________________________________________________________________________ RESUMO: Filmes finos metalicos tem despertado muito interesse devido a possibildade de produzir Ressonancia de Plasmons de Superfıcie (SPR) utilizando uma configuracao de Kretschmann. Esta tecnica e muito sensıvel na determinacao de pequenas mudancas na interface entre uma camada metalica e um meio dieletrico, e os metais usados geralmente sao prata e ouro, uma vez que a ressonancia de plasmon da superfıcie desses metais esta localizada na regiao do visıvel. Esses filmes, devido a sua estabilidade e diversidade de aplicacoes, tem sido extensivamente estudados por tecnicas eletroquımicas, espectroscopia Raman intenficada por superfıcie (SERS) e por tecnicas de microscopia tais como o AFM e STM. A Espectroscopia Raman tem sido utilizada para a analise de compostos organicos em determinados sistemas. No entanto, em sistemas que possuem concentracoes muito baixas, o sinal Raman e extremamente fraco e ineficiente, ou sofre interferencias de ruıdos. Um dos metodos desenvolvidos para aumentar significativamente o sinal de uma especie adsorvida sobre uma superfıcie metalica em varios nıveis e o SERS. Uma das consideracoes importantes para a formacao de um substrato SERS ativo e a rugosidade da superfıcie, e a obtencao dessas superfıcies tem sido realizado de diversas maneiras. No presente trabalho, analisamos o efeito de diferentes ciclos de oxidacao-reducao (ORCs) sobre a superfıcie de filmes finos de ouro, utilizando as tecnicas de voltametria cıclica, microscopias, espectroscopia UV-Vis e SPR, que serao utilizadas para avaliar a eficiencia dos substratos modificados eletroquimicamente como SERS e SPR ativos. Inicialmente, o filme e ciclado em uma solucao de H2SO4 para remover as impurezas da superfıcie. Apos este procedimento, os filmes com espessuras de 50 e 100 nm, depositados sobre um substrato de vidro, foram submetidos a uma serie de ORCs em uma solucao de H2SO4.

Nesta tese foi estudado o espalhamento Raman intensificado pela superfície (SERS) em regime de detecção de uma molécula em eletrodo de prata ativado por ciclos de oxidação e redução. Neste regime, de baixas concentrações, são observadas intensas flutuações de intensidade SERS as quais foram controladas neste substrato pela aplicação de potencial ao eletrodo, o que foi associado a alterações na concentração de moléculas adsorvidas na superfície do eletrodo. Além da dependência com o potencial aplicado, foram estudadas através de simulações Monte Carlo, a contribuição nestas flutuações da constante de adsorção das moléculas, do número de \"hot spots\" (regiões de altas intensificações SERS) e do tipo de \"hot spot\" (em termos de eficiência para detecção de espectros de uma molécula). Através destas simulações foram verificadas flutuações de intensidade muito semelhantes às observadas experimentalmente. Além das flutuações de intensidade foram também observadas flutuações de intensidades relativas, como por exemplo, das relações de intensidades anti-Stokes/Stokes, as quais foram interpretadas segundo um modelo de ressonância, através do qual foi possível estimar as energias de ressonância nos \"hot spots\". Alguns dos resultados indicaram a contribuição de ressonâncias finas, as quais foram interpretadas como resultado de interferências entre ressonâncias de plasmon de superfície. Interferências como estas foram demonstradas através de simulações pelo método DDA (\"Discrete Dipole appoximation\") em modelos simples de \"hot spots\" formados por nanobastões de Au. / In this thesis it was studied surface-enhanced Raman scattering (SERS) at single-molecule detection on Ag electrode activated by oxidation and reduction cycles. At this low concentration limit it was observed strong SERS intensity fluctuations that were controlled by the applied potential to the electrode and this control was associated to changes in surface concentration of adsorbed molecules. Furthermore, it was studied through Monte Carlo simulations the influence of adsorption constant, number of \"hot spots\" (regions of high SERS enhancements) and type of \"hot pot\" (in terms of efficiency for single-molecule detection). With such simulations, it was verified fluctuations of SERS intensities very similar to experimental observations. Besides absolute intensity fluctuations, we also observed fluctuations of relative intensities as, for instance, the. anti-Stokes to Stokes intensity ratios. These fluctuations were interpreted according to a resonance model, which made possible the estimative of resonance energies at the SERS \"hot spots\". Some of these results indicated the existence of sharp resonances that were interpreted as a result of interferences among surface plasmon resonances, which were demonstrated through DDA (Discrete Dipole Approximation) simulations in simple models of \"hot spots\" formed by Au nanorods

Submitted by Rosa Assis (rosa_assis@yahoo.com.br) on 2017-09-21T13:40:28Z No. of bitstreams: 2 PILAR GREGORY VIANNA.pdf: 4126013 bytes, checksum: c4320ab5ecb2ec5dfc641f96b6c6fa51 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Paola Damato (repositorio@mackenzie.br) on 2017-09-22T13:35:43Z (GMT) No. of bitstreams: 2 PILAR GREGORY VIANNA.pdf: 4126013 bytes, checksum: c4320ab5ecb2ec5dfc641f96b6c6fa51 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-22T13:35:43Z (GMT). No. of bitstreams: 2 PILAR GREGORY VIANNA.pdf: 4126013 bytes, checksum: c4320ab5ecb2ec5dfc641f96b6c6fa51 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-01-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Fundação de Amparo a Ciência e Tecnologia / Fundo Mackenzie de Pesquisa / Light interaction with the electronic cloud of metallic nanoparticles at frequencies that are resonant with the natural oscillation frequency of the cloud is known to excite localized surface plasmons. This phenomenon is widely used to enhance the Raman signal, known to have small cross sections. The technique, known as surface-enhanced Raman spectroscopy (SERS), enables the detection of chemical and biological species with high sensitivity. However, charge transfer mechanisms, adsorption/desorption and changes in the substrate morphology induce temporal instability of the SERS signal, known as blinking, which is an obstacle to the precise detection of the molecules under analysis. In this work, we, therefore, propose a SERS substrate composed of graphene oxide and gold nanorods, capable of suppressing the temporal fluctuations in the intensity of the spectrum. Temporal stability is statistically determined by the coefficient of variation of the integrated spectra, from which it is verified that, with the addition of graphene oxide, the nanocomposite is five times more stable than with gold nanorods only. The stability improvement is attributed to the removal of the nanorods’ surfactant from plasmonic hot spots due to graphene oxide-surfactant interaction. Thus, the nanocomposite is used as a reliable SERS substrate in the detection of Rhodamine 640. The analysis indicates a Rodamine detection that is four times more stable with the nanocomposite, than without graphene oxide. The nanocomposite is then used for the coating of the inner surface of microcapillaries. Graphene oxide and gold nanorod suspensions are subsequently used to fill the capillaries, with a drying step for the evaporation of solvents in between each filling stage. The continuous coating of the capillary fibers with the nanocomposite is verified by Raman spectroscopy, and Rhodamine 640 is used as a probe molecule, this time inside the capillaries, for SERS analysis. The microcapillaries allow for the use of small amounts of sample, and smaller concentrations than those detected with other reported optofluidic substrates are measured. / A interação da luz com a nuvem eletrônica de nanopartículas metálicas em frequências que apresentam ressonância com a frequência natural de oscilação da nuvem é conhecida por gerar a excitação de plásmons localizados de superfície. Este efeito é amplamente utilizado na amplificação do sinal Raman, conhecido por possuir baixas seções de choque. A técnica, conhecida como espectroscopia Raman amplificada por superfície (SERS), possibilita a detecção de espécies químicas e biológicas com altíssima sensibilidade. Entretanto, mecanismos de troca de carga, adsorção/dessorção e alterações na morfologia do substrato induzem uma instabilidade temporal do sinal SERS, fenômeno conhecido como blinking, que é um obstáculo na detecção precisa das moléculas em análise. Neste trabalho, propomos, portanto, um substrato SERS composto de óxido de grafeno e nanobastões de ouro, capaz de suprimir as flutuações temporais na intensidade do espectro. A estabilidade temporal é estatisticamente determinada pelo coeficiente de variação da integral do espectro, de onde verifica-se que com a adição de óxido de grafeno, o nanocompósito apresenta estabilidade cinco vezes superior comparado à detecção com nanobastões de ouro somente. A melhoria na estabilidade é atribuída à remoção do surfactante dos nanobastões dos hot spots, o que ocorre devido à interação óxido de grafeno-surfactante. Assim, o nanocompósito é utilizado como um substrato SERS confiável na detecção de Rodamina 640. A análise aponta para uma detecção quatro vezes mais estável da Rodamina no nanocompósito comparada ao sinal proveniente da molécula em nanobastões sem óxido de grafeno. O nanocomposito é, então, utilizado no revestimento das paredes internas de microcapilares para detecção SERS optofluídica. Para isso, suspensões de óxido de grafeno e de nanobastões de ouro eram subsequentemente utilizadas para preencher os capilares, com secagem por evaporação dos solventes entre as etapas de preenchimento. Verifica-se o revestimento contínuo das fibras capilares com o nanocompósito por espectroscopia Raman, e Rodamina 640 é utilizada como mólecula de prova, dessa vez introduzida no interior dos capilares para análises de SERS. Os microcapilares permitem a utilização de pequenas quantidades de amostra, e concentrações inferiores àquelas detectadas com outros substratos optofluídicos reportados na literatura são medidas.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-03T17:33:41Z No. of bitstreams: 1 tatianabittencourtvillelaneves.pdf: 6602146 bytes, checksum: 41b92396bb426d51f4362a8117b77115 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-13T13:39:32Z (GMT) No. of bitstreams: 1 tatianabittencourtvillelaneves.pdf: 6602146 bytes, checksum: 41b92396bb426d51f4362a8117b77115 (MD5) / Made available in DSpace on 2017-05-13T13:39:32Z (GMT). No. of bitstreams: 1 tatianabittencourtvillelaneves.pdf: 6602146 bytes, checksum: 41b92396bb426d51f4362a8117b77115 (MD5) Previous issue date: 2014-03-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os estudos visando o entendimento da interface metal/molécula levaram à descoberta do efeito SERS. Esse efeito foi descoberto casualmente e pode aumentar a intensidade Raman de espécies adsorvidas ca. 106 vezes. O desempenho SERS depende de alguns parâmetros, como: tamanho e forma das nanoestruturas metálicas e natureza do metal. Para evitar agregação e deposição das nanopartículas, uma nova metodologia é proposta nessa dissertação: recobrir a NPs com materiais inertes, como SiO2 e MnO2. A esta metodologia dá-se o nome de SHINERS. Outra técnica que tem ganhado notoriedade devido às aplicações em sistemas biológicos é o efeito SEF. Para que o SEF seja observado é necessário um espaçamento entre o fluoróforo e as NPs, que também pode ser realizado pelo recobrimento com óxidos inertes, quando se utiliza a denominação SHINEF. O distanciamento da superfície provoca um decaimento do sinal; logo, as camadas devem ter alto controle da espessura para que os resultados sejam otimizados. Para o fim de obter desempenho otimizado SHINERS e SHINEF, nessa dissertação foram preparadas NPs de Au e Ag recobertas por camadas ultrafinas de SiO2 e MnO2 de diferentes espessuras. Foi possível caracterizar o recobrimento das NPs metálicas pelos óxidos utilizando TEM. Verificou-se o recobrimento com camadas de 2-6 nm de espessura. O recobrimento das NPs causa um deslocamento para maior comprimento de onda das bandas LSPR das nanopartículas sem recobrimento quando comparadas às NPs com recobrimento, atribuído à mudança do índice de refração local sobre as NPs. Os nanomateriais resultantes tiveram seu desempenho estudado utilizando o corante IR820, que teve seu espectro vibracional atribuído nessa dissertação, como moléculaprova para os dois efeitos de intensificação. Verificou-se uma diminuição da intensidade SHINERS com o aumento da espessura do recobrimento em relação à intensidade SERS, atribuída ao aumento da distância entre adsorbato e superfície das NPs. Para o efeito SHINEF, verificou-se que ocorre uma intensificação apreciável da emissão de fluorescência quando o corante IR-820 na presença das NPs recobertas foi excitado em 785 nm. Os resultados obtidos são promissores para a aplicação das metodologias de preparação de NPs metálicas recobertas como substratos de alto desempenho para as técnicas SHINERS e SHINEF / The studies to aimed the interface metal/molecule resulted in the discovery of the SERS effect. The SERS effect was discovered accidentally and can increase the intensity of scattering adsorbed species ca. 106 times. The SERS performance depends on several parameters such as: size, shape and nature of the metallic nanostructures. To avoid aggregation and deposition of nanoparticles, a new methodology is proposed in this dissertation: coat the NPs with inert materials like SiO2 and MnO2. The cited methodology receives the name of SHINERS. Another technique that has been receiving great notoriety due to applications in biological systems is the SEF effect. A specific spacing between the fluorophore and NP is necessary for the SEF effect to occur and it can be accomplished by coating with inert oxides, which takes the denomination of SHINEF. The distance from the surface causes a decay of the signal, therefore, the layers are supposed to be ultrathin with precise thickness control for optimized results. In order to obtain a good SHINERS and SHINEF performance, in this dissertation, Ag and AuNPs coated with ultrafine layers of SiO2 and MnO2 to different thicknesses were prepared. It had been possible to characterize the coating of metal oxide NPs by using TEM. It has been determined covering oxide layer thickness of 2-6 nm. The coating of NPs causes a shift of LSPR bands for higher wavelength of the coating nanoparticles compared to uncoated NPs, assigned to increasing changes in the local refractive index of the NPs with the oxide layer thickness. The resulting nanomaterials performances for SHINERS and SEF effect were studied using IR-820 dye, which had its vibrational spectrum assigned. There has been observed a decrease in the SHINERS intensity with the increasing thickness of the coating in relation to the SERS intensity attributed to the increasing distance of the adsorbate from the NPs surface. For SHINEF effect, it has been found that a significant enhancement of fluorescence emission occurs when IR- 820 dye in the presence of the coated NPs excited at 785 nm. The preparative methodologies proposed in this dissertation are promising for the application of coated Ag and Au NPs as substrates for high performance SHINERS and SHINEF techniques.

Orientador: Ronei Jesus Poppi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-24T17:49:24Z (GMT). No. of bitstreams: 1 MamianLopez_MonicaBenicia_D.pdf: 23169913 bytes, checksum: cf40556e2a6f09ccb3f2b2bf36b0b234 (MD5) Previous issue date: 2014 / Resumo: Foi utilizada a espectroscopia Raman amplificada por superfície SERS, em conjunto com ferramentas quimiométricas de resolução de curvas e alguns algoritmos complementares, em quatro aplicações analíticas que incluíram imagem SERS, monitoramento de um sistema dinâmico multicomponente e quantificação de nicotina e moxifloxacina em urina. Como intensificadores do sinal foram empregados um sistema coloidal de ouro, sintetizado segundo o método de Lee-Miesel e um substrato sólido comercial de ouro nanoestruturado / Abstract: In this work, four chemometric-assisted analytical procedures using surface-enhanced Raman spectroscopy are proposed. A multivariate curve resolution method in conjuction with others algorithms were employed to quantify the alkalloid nicotine in presence of two related compounds; determinate the antibiotic moxifloxacin in urine and to study its photolyitic degradation. Besides, SERS imaging was applied to study the paracetamol distribution in polymeric films. As SERS enhancers were used colloidal gold and a nanostructured gold substrate / Doutorado / Quimica Analitica / Doutora em Ciências