For the last decade, semiconducting nanowires synthesized by bottom-up methods have opened up new opportunities, stimulated innovative scientific research, and led to applications in materials science, electronics, optics, and biology at the nanoscale. Notably, nanowire building blocks with precise control of size, structure, morphology, and even composition in one, two, and three dimensions can successfully demonstrate high-performance electrical characteristics of field-effect transistors (FETs) and highly sensitive, selective, label-free, real-time biosensors in the fields of nanoelectronics and nano-biosensing, respectively. This thesis has focused on the design, synthesis, assembly, fabrication and electrical characterization of nanowire heterostructures for a proof-of-concept nanoprocessor and morphology-modulated kinked nanowire molecular nanosensor. / Physics

Nanotechnology is emerging to be one of the most important scientific disciplines that physics, chemistry and biology truly overlap with each other. Over the last two decades science and technology have witnessed tremendous improvement in the hope of unveiling the true secrets of the nature in molecular or atomic level. Today, the regime of nanometer is truly reached. ZnO is a promising material due to the wide direct band gap (3.37 eV) and the room temperature large exciton binding energy (60 meV). Recent studies have shown considerable attraction towards ZnO nanostructures, particularly on one-dimensional ZnO nanorods, nanowires, and nanotubes due to the fact that, for a large number of applications, shape and size of the ZnO nanostructures play a vital role for the performance of the devices. The noncentrosymmetric property of ZnO makes it an ideal piezoelectric material for nanomechanical devices. Thus, mechanical characterization of one dimensional ZnO nanostructures including strength, toughness, stiffness, hardness, and adhesion to the substrate is very important for the reliability and efficient operation of piezoelectric ZnO nanodevices. Moreover, owing to the large effective surface area with high surface-to-volume ratio, the surface of one dimensional ZnO nanowires, nanorods, and nanotubes is very sensitive to the changes in surface chemistry and hence can be utilized to fabricate highly sensitive ZnO electrochemical sensors. This thesis studies mechanical properties and electrochemical sensor applications of ZnO nanostructures. The first part of the thesis deals with mechanical characterization of vertically grown ZnO nanorods and nanotubes including buckling, mechanical instability, and bending flexibility. In paper I, we have investigated mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on Si, SiC, and sapphire substrates by vapor-liquid-solid (VLS) method. The critical loads for the ZnO nanorods grown on Si, SiC, and sapphire were measured and the corresponding buckling and adhesion energies were calculated. It was found that the nanorods grown on SiC substrate have less residual stresses and are more stable than the nanorods grown on Si and sapphire substrates. Paper II investigates nanomechanical tests of bending flexibility, kinking, and buckling failure characterization of vertically aligned single crystal ZnO nanorods/nanowires grown by VLS and aqueous chemical growth (ACG) methods. We observed that the loading and unloading behaviors during the bending test of the as-grown samples were highly symmetrical and the highest point on the bending curves and the first inflection and critical point were very close. The results also show that the elasticity of the ZnO single crystal is approximately linear up to the first inflection point and is independent of the growth method. In Paper III, we quantitatively investigated the buckling and the elastic stability of vertically well aligned ZnO nanorods and ZnO nanotubes grown on Si substrate by nanoindentation technique. We found that the critical load for the nanorods was five times larger than the critical load for nanotubes. On the contrary, the flexibility for nanotubes was five times larger than nanorods. The discovery of high flexibility for nanotubes and high elasticity for nanorods can be utilized for designing efficient piezoelectric nanodevices. The second part of this thesis investigates electrochemical sensor applications of ZnO nanorods, nanotubes , and nanoporous material. In paper IV, we utilized functionalized ZnO nanorods on the tip of a borosilicate glass capillary coated with ionophore-membrane to construct intracellular Ca2+ selective sensor. The sensor exhibited a Ca2+-dependent electrochemical potential difference and the response was linear over a large dynamic concentration range, which enabled this sensor to measure Ca2+ concentrations in human adipocytes or in frog oocytes. The results were consistent with the values of Ca2+ concentrations reported in the literature. In paper V, ZnO nanotubes and nanorods were used to create pH sensor devices. The developed ZnO pH sensors display good reproducibility, repeatability, and long-term stability. The ZnO pH sensors exhibited a pH-dependent electrochemical potential difference over a large dynamic pH range. We found that the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods. The possible reasons of enhanced sensitivity were explained. Paper VI investigates an improved potentiometric intracellular glucose biosensor based on the immobilization of glucose oxidase on the ZnO nanoporous material. We demonstrated that using ZnO nanoporous material as a matrix material for enzyme immobilization improves the sensitivity of the biosensor as compared to using ZnO nanorods. In addition, the fabrication method of the intracellular biosensor was simple and excellent performance in sensitivity, stability, selectivity, reproducibility, and anti-interference was achieved.

Nanotechnology is an emerging inter-disciplinary paradigm which encompasses diverse fields of science and engineering converge at the nanoscale. This nanoscale science and nanostructure engineering have well demonstrated in the fabrication of sensors/transducers devices with faster response time and better sensitivity then the planer version of the sensor’s configurations. Nanotechnology is not just to grow/fabricate nanostructures by just mixing nanoscale materials together but it requires the ability to understand and to precisely manipulate and control of the developed nanomaterials in a useful way. Nanotechnology is aiding to substantially improve, even revolutionize, many technology and industry sectors like information technology, energy, environmental science, medicine/medical instrumentation, homeland security, food safety, and transportation, among many others. Such applications of nanotechnology are delivering in both expected and unexpected ways on nanotechnology’s promise to benefit the society. The semiconductor ZnO with wide band gap (~ 3.37 eV) is a distinguish and unique material and its nanostructures have attracted great attention among the researchers due to its peculiar properties such as large exciton binding energy (60 meV) at room temperature, the high electron mobility, high thermal conductivity, good transparency and easiness of fabricating it in the different type of nanostructures. Based on all these fascinating properties, ZnO have been chosen as a suitable material for the fabrication of photonic, transducers/sensors, piezoelectric, transparent and spin electronics devices etc. The objective of the current study is to highlight the recent developments in materials and techniques for electrochemical sensing and hetrostructure light emitting diodes (LEDs) luminescence properties based on the different ZnO nanostructures. The sensor devices fabricated and characterized in the work were applied to determine and monitor the real changes of the chemical or biochemical species. We have successfully demonstrated the application of our fabricated devices as primary transducers/sensors for the determination of extracellular glucose and the glucose inside the human fat cells and frog cells using the potentiometric technique. Moreover, the fabricated ZnO based nanosensors have also been applied for the selective determination of uric acid, urea and metal ions successfully. This thesis relates specifically to zinc oxide nanostructure based electrochemical sensors and photonic device (LED) applications.

An electrochemical sensor array can provide information about the spatial and temporal distribution of chemicals in liquid turbulent plumes. Planar laser induced fluorescence (PLIF) and amperometric sensor arrays were used to record signals from modulated chemical plumes released into a recirculating aquatic flume. Coherence analysis was applied to extract the frequency components contained in the sensor response. Effects due to release distance, modulation frequency, and array orientation were investigated. This study has demonstrated that frequency encoded information can be extracted from a turbulent chemical plume using an array of amperometric sensors with optimized three-dimensional geometry and tuning.

Orientador: Yoshitaka Gushikem / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T00:21:21Z (GMT). No. of bitstreams: 1 Santos_LucasSamuelSoaresdos_M.pdf: 849824 bytes, checksum: c851854489d52e302069aa7b55903044 (MD5) Previous issue date: 2010 / Resumo: No presente trabalho realizou-se a síntese do óxido misto SiO2/SnO2 através do processo sol-gel e sobre esse óxido misto realizou-se a síntese in-situ de ftalocianina de manganês (II). Esse material foi caracterizado por técnicas físicas e químicas e seu potencial como sensor foi estudado utilizando técnicas eletroquímicas. Através da técnica de fluorescência de raios-X, determinou-se a concentração de 15% em massa de SnO2 no óxido misto. O valor de área superficial foi de As(BET) = 299 m.g, com uma predominância de microporos em sua estrutura. Imagens obtidas por MEV e mapeamentos obtidos por EDS, mostraram uma boa dispersão dos elementos no óxido misto e no material SiO2/SnO2/MnPc. Através de medidas de reflectância difusa e IV-TF, foi possível observar a presença da ftalocianina de manganês (II) no material SiO2/SnO2/MnPc. Para a caracterização eletroquímica do material foram utilizados dois tipos de eletrodo: o eletrodo de pasta de carbono e o eletrodo de disco rígido. Ambos os eletrodos apresentaram uma relação linear entre a corrente de pico catódico e a concentração de O2, mostrando que podem ser aplicados como sensores. O eletrodo de disco rígido apresentou melhor desempenho, com maior resistência mecânica, melhor reprodutibilidade e tempo de vida útil mais longo. O mecanismo de eletrocatálise ocorrido envolveu 4 elétrons na reação, como é preferível, já que forma água como produto da reação: O2 + 4 e + 4 H 2 H2O / Abstract: In this work the preparation of the mixed oxide SiO2/SnO2 by sol-gel processing method and the in-situ synthesis of manganese (II) phthalocyanine in the pores of the matrix are described. By means of X-ray fluorescence technique, the concentration of SnO2 in mixed oxide was determined as being 15 wt%. The specific surface area As(BET) = 299 m.g with micropores predominance in the structure were found. Images obtained by SEM and mappings by EDS showed a homogeneous dispersion of the components in the SiO2/SnO2/MnPc material. MnPc in the pores of the matrix was characterized by the solid state UV-Vis diffuse reflectance and by FT-IR techniques. The usefulness of the material as an electrochemical sensor for dissolved oxygen in water was studied. Electrochemical studies were carried out by using two types of electrodes: (a) carbon paste modified and (b) hard pressed graphite disk. Both electrodes showed a linear relationship between catodic peak current and the concentration of O2, indicating that they can be applied as an electrochemical sensors of dissolved oxygen in water. The hard pressed disk electrode showed a better performance towards oxygen determination since it presents a greater mechanical resistance associated with better reproducibility and longer useful lifetime. The electrocatalytic oxidation involved four electrons, a preferable mechanism in the present case since only water as the reaction product is produced: O2 + 4 e + 4 H 2 H2O / Mestrado / Quimica Inorganica / Mestre em Química

Orientador: Yoshitaka Gushikem / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T23:27:35Z (GMT). No. of bitstreams: 1 Cardoso_WilliamdaSilva_D.pdf: 740346 bytes, checksum: bbae1435b7392cf211b02cc55af7333d (MD5) Previous issue date: 2005 / Doutorado / Quimica Inorganica / Doutor em Ciências

Made available in DSpace on 2014-07-29T15:01:52Z (GMT). No. of bitstreams: 1 dissertacao_Ana Elisa.pdf: 1011464 bytes, checksum: 0fe4be232b2f56c521e72d6557985d3c (MD5) Previous issue date: 2010-02-09 / The developmental impulse of the present time has caused a continuous degradation of the environment, which increases the need of monitoring the contaminant levels launched in the natural water courses and industrial effluents. In this context, it is crucial to develop new methodologies of determination and quantification of various types of pollutants, with rapidity, selectivity and sensitivity, characteristics which were found in the chemically modified electrodes (CMEs). Many industrial processes are polluting the sources of water resources, such as the petrochemical industries and paper and cellulose industries. From those, sulfide is frequently set free causing serious demages due to its high toxicity, even in low concentrations, which suggests methods of detention of sulfide of high sensitivity, reduced time and low cost. Some analytical methodologies for the detention of sulfide are based on the reaction with methylene blue, which has recognized mediating electron capacity. Accordingly, the development and characterization of CMEs, modified with silica-niobium-methylene blue possess promising characteristics and great potential of use in these analyses. Studies of the voltametric behavior of CMEs had been carried through with different concentrations of SNAM. Beyond the effect of the paste composition, also the effect of the type of electrolyte support and of the pH had been investigated. The CMEs had been studied by cyclic voltammetry, linear voltammetry and chronoamperometry technique, presenting good reply to the ion sulfide in the linear response range between 7.59 x 10¬6 and 6,34 x 10¬5 moI L¬ 1, with correlation coefficient (r) of 0, 9979, detection limit of 2,03 x 10-6mol L-1 and quantification limit of 6,77 x 10¬6 moI L¬ 1. The results gotten in this work has allowed to conclude that the carbon paste modified with SNAM presents a good analytical performance for analysis of sulfide in samples of environmental interest / O impulso desenvolvimentista da atualidade tem provocado a necessidade de se monitorar continuamente o teor de contaminantes lançados nos cursos de águas naturais e efluentes industriais. Neste contexto, é essencial o desenvolvimento de novas metodologias de determinação e quantificação de diversos tipos de poluentes, com rapidez, seletividade e sensibilidade, características estas, encontradas nos eletrodos quimicamente modificados (EQM). Vários processos industriais são fontes poluidoras dos recursos hídricos, tais como indústrias petroquímicas, de papel e celulose. O sulfeto é frequentemente liberado por essas indústrias e causa sérios danos devido a sua alta toxicidade mesmo em baixas concentrações, o que sugere métodos de detecção de sulfeto de alta sensibilidade, tempo reduzido e baixo custo. Várias metodologias analíticas para detecção de sulfeto se baseiam na reação com azul de metileno, que por sua vez possui reconhecida capacidade mediadora de elétrons. Nesse sentido o desenvolvimento e caracterização de EQM modificado com sílica-nióbio-azul de metileno, possui características promissoras e grande potencial de utilização nessas análises. Foram realizados estudos do comportamento voltamétrico de EQMs de pasta de carbono modificados com diferentes concentrações de SNAM. Foram investigados além do efeito da composição da pasta, efeitos do tipo de eletrólito suporte e do pH. O EQM foi estudado por voltametria cíclica, voltametria linear e cronoamperometria, apresentando boa resposta ao íon sulfeto nas faixas lineares de concentração de 7.59 x 10-6 a 6.34 x 10-5 mol L-1, com coeficientes de correlação (r) de 0,9979, limite de detecção de 2,03 x 10-6mol L-1 e limite de quantificação de 6,77 x 10-6 mol L-1. Os resultados obtidos neste trabalho permitiram concluir que a pasta de carbono modificada com SNAM apresenta um bom desempenho analítico para análise de sulfeto, garantindo boa sensibilidade, o que pode tornar-se uma alternativa vantajosa para determinação de sulfeto em amostras de interesse ambiental

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T15:45:15Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Alexandre K. P. Souza.pdf: 3464696 bytes, checksum: e78461b89f866435b0635d96ae2a3f7d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T15:45:30Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Alexandre K. P. Souza.pdf: 3464696 bytes, checksum: e78461b89f866435b0635d96ae2a3f7d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T15:46:53Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Alexandre K. P. Souza.pdf: 3464696 bytes, checksum: e78461b89f866435b0635d96ae2a3f7d (MD5) / Made available in DSpace on 2017-02-20T15:46:53Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Alexandre K. P. Souza.pdf: 3464696 bytes, checksum: e78461b89f866435b0635d96ae2a3f7d (MD5) Previous issue date: 2016-12-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Electronic devices for applications in the field of electronic instrumentation in the offshoot of analytical chemistry research have great interest in the field of research related to the academic environment, as well as in the industrial environment. With the objective of extracting information and relevant data of chemical compounds, both from the qualitative point of view, as well as from the quantitative point of view, it is necessary in electrochemical analyzes, the presence of specific electrochemical sensors connected to electronic circuits, thus forming Electrochemical systems designed with the purpose of processing and extracting data information related to the physico-chemical effects occurring on the surface of the sensor due to reactions in the chemical substance or compound of interest in a particular analysis. This work deals with the research, study and development of topologies of electronic circuits, known as potentiostat, having as main objective, the task of conditioning of electrical signals from an electrochemical sensor, called electrochemical cell of three electrodes. The results demonstrated in this work are concentrated in the graphs of electrical voltages and currents, directly related to the chemical parameters of a sample under analysis, being these results obtained through experimental tests, applying the cyclic voltammetry method. Experimental tests were performed with circuit topologies connected to a cell, for the analysis of data obtained and validation of proposed potentiostat circuit topologies. / Dispositivos eletrônicos voltados para aplicações na área de instrumentação eletrônica no ramo de pesquisas em química analítica possuem grande interesse de desenvolvimento, nos campos de pesquisas relacionados ao meio acadêmico, assim como, no ambiente industrial. Com o objetivo de extrair informações e dados relevantes de compostos químicos, tanto do ponto de vista qualitativo, bem como do ponto de vista quantitativo, faz-se necessário em análises eletroquímicas, à presença de sensores eletroquímicos específicos conectados a circuitos eletrônicos, formando desta maneira sistemas eletroquímicos, projetados com a função de processar e extrair informações de dados relacionados aos efeitos físico-químicos, que ocorrem na superfície do sensor, devido a reações na substância ou composto químico de interesse em determinada análise. Este trabalho aborda a pesquisa, estudo e desenvolvimento de topologias de circuitos eletrônicos, conhecidos como potenciostato, tendo por tarefa o condicionamento de sinais elétricos provenientes de um sensor eletroquímico, designado de célula eletroquímica de três eletrodos. Os resultados demonstrados neste trabalho estão concentrados no levantamento de gráficos de sinais elétricos de tensões e correntes, relacionados diretamente a parâmetros químicos de uma amostra em análise, sendo estes resultados obtidos através de testes experimentais, aplicando o método de voltametria cíclica. Foram realizados testes experimentais com as topologias de circuitos conectados a uma célula, para a análise dos dados obtidos e validação das topologias de circuitos de potenciostatos propostos

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-09-29T01:08:32Z No. of bitstreams: 1 Andressa_G_Rosenberger_2017.pdf: 2187152 bytes, checksum: eeb5c275b57d9c489c86178a66925400 (MD5) / Made available in DSpace on 2017-09-29T01:08:32Z (GMT). No. of bitstreams: 1 Andressa_G_Rosenberger_2017.pdf: 2187152 bytes, checksum: eeb5c275b57d9c489c86178a66925400 (MD5) Previous issue date: 2017-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná (FA) / Water is a vital element in human health and a determining factor in the pace of human evolution; however, the presence of emerging pollutants threatens its quality and may endangers the well-being of people and the environment. This work stands out for the development of a composite material based on nanotechnology to be used as an electroanalitic sensor in aqueous solutions with the Metronidazole drug which is considered an emerging pollutant. Initially the polymeric fibers were produced based on ecovio® and carbon nanotubes multilayer (MWCNT’s). In order to evaluate the parameters that could interfere in the process of electrospinning and to understand the interaction between the polymer and the MWCNT’s, a fractional factorial design and physicochemical characterizations analysis were used, which were: optical micrography scanning electron microcopy (SEM), mechanical analysis, wettability by contact angle, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DSC) and X-ray diffraction. For the porpuse of fabricating the sensor, the fibers were calcinated and the obtained residue was characterized by SEM and FTIR. The statistical data and the images of optical microscopy and SEM showed that the addition of MWCNT’s is the parameter that most influences the diameter of the obtained microfibers (1.16 ± 0.22 µm) so that their presence decreases the diameter and results in fibers more uniform and homogeneous. After selecting the ideal conditions an experiment was done with the following process and solution parameters: concentration of ecovio® 15,00% (m/v) and MWCNT’s 0,60% (m/v); flow: 1.80 mL.h-1; distance: 16 cm and applied voltage: 18 kV. The morphology and diamater os the fibers was obtained using SEM images and showed an average diameter of 1.59±0.61 µm. It was also demonstrated a better mechanical performance after the addition of MWCNT’s to the fibers, so that they presented greter elasticity (180%) and significant increase on the elastic resistance (163%) and tensile strength (107%), besides the analysis of wettability from the contact angle suggest that the carbon-based nanomaterial is inside the polymeric microfibers. The interactions between the MWCNT’s and the polymer were better evaluated by vibracional aspects by Fourier transform infrared spectroscopy (FTIR) and showed the interaction between the MWCNT’s and the functional group C=O characteristic of the group ester of the polymers. The analysis of thermogravimetry (TGA) demonstrated a higher stability. The thermogravimetric analysis (TGA) showed a higher stability of the poly (lactic acid) component and lower resistances of the poly (butylene adipate co-terephtalate) component in the polymer blend. Besides it was necessary a constant temperature of 550 ºC during 50 minutes to the total degradation of the polymer. By differential thermal analysis (DSC) it was possible to confirm the interactions proposed by FTIR and TGA, which indicate that the interaction occurs preferentially with the aliphatic chains of the ecovio® polymer. After the calcination of the fibers, the obtained residue was characterized by FTIR and MEV and variations in the characteristics of pure MWCNT's can be observed, with reduction of the corboxylic groups for the calcined and electrospun/calcined MWCNT's, as well as the formation of lamella for the MWCNT's electrospun/calcined. The electrochemical measurements using the cyclic voltammetry technique showed that the sensor is promising for determination of Metronidazole. / A água é um elemento vital e determinante no ritmo da evolução humana, contudo a presença de poluentes emergentes ameaça sua qualidade e põe em risco o bem estar humano e ambiental. O presente trabalho destaca-se por desenvolver um material compósito formado por poli (butileno adipato co-tereftalato) (PBAT) e poli (ácido lático) (PLA) para ser utilizado como sensor eletroanalítico em soluções aquosas contendo o fármaco metronidazol. Inicialmente produziu-se fios poliméricos a base de ecovio® e nanotubos de carbono de paredes múltiplas (MWCNT’s). A fim de avaliar os fatores interferentes do processo e compreender a interação entre o polímero e os MWCNT’s utilizou-se um planejamento fatorial fracionário e análises de caracterização físico-química tais como: micrografia ótica, microscopia eletronica de varredura (MEV), análise mecanica, molhabilidade por angulo de contato, espectroscopia vibracional de infravermelho por transformada de Fourrier, análise termogravimétrica (TGA), calorimetria exploratória diferencial (DSC) e difratometria de raio X (DRX).Para a construção do sensor eletroquímico as fibras foram calcinadas e o resíduo obtido foi caracterizado pelas ténicas de MEV e FTIR. Os resultados estatísticos em conjunto com as imagens de microscopia ótica e MEV demonstram que a adição de MWCNT’s é o parâmetro que mais influência no diâmetro das microfibras (1,16 ± 0,22 µm) obtidas, de modo, que sua inserção diminui este parâmetro deixando as fibras mais uniformes e homogêneas. Após a escolha das condições ideais procedeu-se um experimento com os seguintes parâmetros da solução e do processo de eletrofiação: ecovio® 15,00% (m/v) e MWCNT’s 0,60% (m/v); fluxo: 1,80 mL.h-1; distância: 16 cm e tensão: 18 kV. A morfolagia e o diâmetro das fibras foram realizadas usando as imagens de MEV e apresentam diâmetro médio de 1,59±0,61 µm. Foi evidenciado também um melhor desempenho mecanico após a inserção de MWCNT’s às fibras de modo que as fibras apresentam maior elasticidade (180%) e um aumento significativo da resistência elástica (163%) e tensão de ruptura (107%). Ademais a análise de molhabilidade por ângulo de contato sugere que o nanomaterial a base de carbono encontra-se no interior das microfibras poliméricas. As interações entre o MWCNT’s e os polímeros foram melhor avaliadas pelos espectros vibracionais de infravermelho por transformada de Fourrier (FTIR) e evidenciam a interação entre MWCNT’s e o grupamento funcional C=O, característicos dos grupamentos ésteres dos polímeros. As análises de termogravimetria (TGA) demonstram uma maior estabilidade do componente poli (ácido lático) e uma menor estabilidade do poli (butileno adipato co-tereftalato) na blenda polimérica, além disso, foi necessário uma temperatura constante de 550 ºC durante 50 minutos para degradar totalmente o polímero.Pela análise térmica diferencial (DSC) foi possível confirmar as interações propostas pelo FTIR e TGA, que indicam que a interação ocorre preferencialmente com as cadeias alifáticas do polímero ecovio®. Após a calcinação das fibras, para o preparo do sensor, o resíduo obtido foi caracterizado por FTIR e MEV e pode-se observar mudanças na caracteristica dos MWCNT’s puros com diminuição dos grupos carboxilicos para os MWCNT’s tratados termicamente e eletrofiados/calcinados, além da formação de lamelas para o MWCNT’s eletrofiados/calcinados. As medidas eletroquímicas usando a tecnica de voltametria cíclica, mostram que o sensor é promissor para determinação de metronidazol.

Recently, laser scribed graphene (LSG) technology has shown great potential for the development of a plethora of sensing platforms due to its high sensitivity, 3D porous structure, and flexibility. Molecularly imprinted polymers (MIPs) have shown high potential as recognition elements for many applications such as biosensing. Hence, we report in this thesis a novel biosensing platform that utilizes nanostructured gold to enhance the performance of LSG sensors coupled with a biomimetic MIP biosensor. To the best of our knowledge, this is the first report of a nanostructured gold modified MIP based LSG biosensor to detect HER-2, which is an important breast cancer biomarker. HER-2 positive breast cancer is more aggressive and does not respond to the same treatment as standard breast cancer. As such, a simple and accurate sensing approach is highly needed for early detection of this type of cancer biomarkers. The LSG sensor platform was fabricated by irradiation of polyimide substrates using a CO2 laser under optimized conditions. Nanostructured gold was electrodeposited onto LSG to enhance its sensitivity and active surface area. Deposition parameters such as deposition voltage, deposition time, and gold chloride (HAuCl4) concentration were optimized to yield complete nanostructured gold coverage and enhanced electrical conductivity of LSG-Au electrodes. A deposition voltage of -0.9 V at 50 mM HAuCl4 for 4 minutes proved to be the optimal condition for gold deposition to yield a 150% peak current enhancement. To fabricate our MIP biosensor, 3,4- ethylenedioxythiophene (EDOT) was chosen from several functional monomers to form PEDOT due to its high conductivity and synergy with nanostructured gold. Electropolymerization of EDOT is performed after adsorbing 0.4mg/mL of HER-2 on the LSG-Au electrode for 20 min. The efficiency of LSG-Au-MIP was optimized by choosing an appropriate extraction agent and HER-2 concentration to be adsorbed on gold. The developed sensing strategy could differentiate between three rebinding concentrations of 10 ng/mL, 100ng/mL, and 200 ng/mL, which is sufficient to determine the HER-2 status of breast cancer since the clinical cut-off is 30.5ng/mL. The developed sensing strategy showed a high degree of novelty and could be useful for the non-invasive detection of cancer biomarkers.