Orientador: Antonio Riul Júnior / Banca: Cleber Renato Mendonça / Banca: Nilson Cristino da Cruz / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Fabricamos neste trabalho microcanais em uma matriz de PDMS para otimização de uma configuração que permita, futuramente, a inserção de eletrodos interdigitados no interior dos mesmos para a integração da "língua eletrônica" que estamos trabalhando ao longo dos últimos anos com dispositivos "lab-on-a-chip". O objetivo final é a fabricação de um sensor "tongue-on-a-chip", não havendo nada similar na literatura até o presente momento, tendo-se em vista, principalmente, o potencial de aplicação de ambos dispositivos ("língua eletrônica" e "lab-on-a-chip"). Neste sentido, esta dissertação torna-se uma chave importante para o desenvolvimento de uma tecnologia nova e com forte apelo comercial. Como a fabricação dos microcanais envolve técnicas e equipamentos de litografia que não dispomos em nossos laboratórios, estendemos colaborações com o laboratório Nacional de Luz Síncroton (LNLS - através de um projeto específico nessa linha de atuação), onde fabricamos os microcanais e eletrodos interdigitados envolvidos neste trabalho. Como é a primeira vez que a microfluídica está sendo aplicada em dispositivos do tipo "língua eletrônica", tivemos um trabalho minucioso de verificação das melhores condições envolvidas na fabricação dos dispositivos. As medidas em fluxo no interior dos microcanais mostraram-se mais rápidas e eficientes que as estáticas utilizadas anteriormente, e, adicionalmente à redução no volume das amostras analisadas com os microcanais, necessitamos ainda de um refinamento para aplicações futuras (análises clínicas e biológicas, controle ambiental, análise de bebidas...), pois o maior empecilho encontrado até o momento tem sio a selagem do dispositivo devido à deposição de filmes ultrafinos sobre os eletrodos metálicos, que esperamos resolver em trabalhos futuros. / Abstract: In this work microchannels were fabricated in a PDMS matrix to optimize a configuration that allows, in future works, the insertion of interdigitated electrodes into the microchannel for the integration of the electronic tongue that we have being working in the last couple of years with lab-on-a-chip devices. The final goal is the fabrication of a tongue-on-a-chip sensor, having nothing similar in the literature up to date, bearing in mind the high potential of application of both devices (electronic tongue and lab-on-a-chip). In that sense, this Msc work becomes an important key to the development of a new technology with strong commercial appeal. As the microchannel fabrication needs equipments and techniques not available in our laboratory, we extend the collaboration with the Brazilian Synchrotron Light Laboratory (LNLS - throughout a specific project in this area) where the microchannels and interdigitated electrodes were fabricated. As it is the first time microfluidic is applied in e-tongue sensors, we did a detailed work verifying the best conditions involved in the device fabrication. Flow measurements inside the microchannels shown to be faster and more efficient than the static ones previously made, and, besides the volume reduction of the samples analysed with the microchannels, we still need a refinement for future applications (clinical and biological analysis, environmental control, beverage analysis, ...), as the major problem has being the sealing of the device due to the deposition of ultra-thin films onto the interdigitated electrodes, which we hope to solve in future works. / Mestre

The components necessary to propagate a synthetic ionic signal are described, and experiments leading to the required experimental system are the focus of this work. Two thiol-derivatized fluorescent probe molecules were synthesized that balanced both electrochemical and fluorescent properties necessary for trace analysis. Self-assembled monolayers (SAMs) of 11-(1-1’-biphenyl-4-yloxy)-1-undecanethiol were formed on Au/glass slides by open-circuit incubation and potential-assisted adsorption methods. A potentiostat was built capable of producing current responses on the microsecond time-scale. Monolayer integrity was established by two methods: cyclic voltammetry and chronoamperometry. Monolayers formed under potential-assisted adsorption conditions showed attenuation of the peak current due to Fe(CN)6 3−/4− redox probe in cyclic voltammetry, indicating a tightly packed monolayer. Chronoamperometric studies also confirmed the monolayer integrity by fitting the current response of a potential-step to an equivalent circuit. The chronoamperometric study was dependent on solvent and electrolyte. In water, the difference between bare Au and monolayer protected Au was large, whereas in DMF, the difference was negligible. Likewise, the use of tetra-butyl ammonium hexafluorophosphate as the electrolyte showed little difference between bare Au and monolayer protected Au. The electrochemical reduction of the SAMs was done in various solvents and electrolytes and the products were analysed by HPLC with fluorescent detection. Along the series of solvents from water to MeCN to DMF the current efficiencies for release increased but still were very low. In water and MeCN, the thiol was the sole detectable product, while in DMF, the sole detected product was the disulfide. Reproducibility of release was poor in MeCN and water, probably due to the low solubility of the thiol. Single-channel analysis of two acyclic bola-amphiphiles (diester and diamide) was done to establish their feasibility as components of a synthetic signal propagation system. Channels from the diester derivative have a Na+ conductance of 10.2 pS and a Cs+ conductance of 39.3 pS. Channels from the diester have a Cs+/Na+ permeability ratio of 4.7, Cs+/Cl- permeability ratio of 7.5 and a Na+/Cl- permeability ratio of 3.1. Channels of the diester bola-amphiphile have two lifetimes; 117 ms and 842 ms at -100 mV, 1 M CsCl electrolyte and DiPhyPC lipid at 25 °C. Similarly, Channels from the diamide derivative have a Na+ conductance of 10.3 pS and a Cs+ conductance of 38.9 pS. Chaimels of the diamide have a Cs+/Na+ permeability ratio of 5.2, Cs+/Cl- permeability ratio of 7.2 and a Na+/Cl- permeability ratio of 2.1. The diamide bola-amphiphile channels have a lifetime of 277 ms at +100 mV, 1 M CsCl electrolyte and DiPhyPC lipid at 25 °C. Both channels show a regular non-uniform step-conductance pattern. The sublevel openings, when graphically represented with lifetime data, show the trend that the lower conductance states of one-level openings are also the shorter-lived channels. A traceless linker to release alcohols from a gold surface was developed. Thiobutyric acid was found to undergo intramolecular thiolactone formation after electrochemical reduction from an Au-electrode to liberate the alcohol. A thiobutyric ester at the C-terminus of gramicidin was synthesized. This compound released gramicidin by chemical reduction with DTT as seen by HPLC analysis and MALDI TOF MS. The electrochemical release of the Au-immobilized thiobutyric ester of gramicidin adjacent to a lipid bilayer, as monitored by bilayer clamp technique, produced an increase in channel activity that is consistent with incorporation of gramicidin. / Graduate

付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22469号 / 工博第4730号 / 新制||工||1739(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 近藤 輝幸, 教授 梅田 眞郷 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Alkanethiols spontaneously assembles from solution or vapour on oxide free metal surfaces resulting in a close-packed molecular stuctures with a high degree of orientation and molecular order. In this study, inkjet printing technique is used to immobilize monolayers of alkanethiols on gold electrodes. The quality of the inkjetted monolayers are analyzed by electrochemical methods, i.e. cyclic voltammetry and electrochemical impedance spectroscopy, and by Polarization Modulation Infrared Reflection-Absorption Spectroscopy (PM-IRRAS) which show a similar molecular quality to those produced by immersion technique, the standard technique. The kinetic and mass transfer behaviours of micro-scale structures of inkjetted monolayers, e.g. bands and dots array electrodes, are explored by electrochemical methods. The microscale inkjetted structures of monolayers are of interest in the fields of microelectronic devices (e.g. chemical and biosensors) and optoelectronic devices. Taking benefits from multichannel existing in the printhead, mixtures of SAMs are demonstrated. Mixing of monolayers differing in functional groups provides a model surface to study interface phenomena at molecular level such as ion permeation, selective chemical binding, and electron transfer kinetic.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17886号 / 工博第3795号 / 新制||工||1580(附属図書館) / 30706 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 杉村 博之, 教授 酒井 明, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Advances in microfabrication and surface chemistry techniques have provided a new paradigm for the creation of in vitro systems for studying problems in biology and medicine in ways that were previously not practical. The ability to create devices with micro- to nano-scale dimensions provides the opportunity to non-invasively interrogate and monitor biological cells and tissue in large arrays and in a high-throughput manner. These systems hold the potential to, in time, revolutionize the way problems in biology and medicine are studied in the form of point-of-care devices, lab-on-chip devices, and biological microelectromechanical systems (BioMEMS). With new in vitro models, it will be possible to reduce the overall cost of medical and biological research by performing high-throughput experiments while maintaining control over a wide variety of experimental variables. A critical aspect of developing these sorts of systems, however, is controlling the device/tissue interface. The surface chemistry of cell-biomaterial and protein-biomaterial interactions is critical for long-term efficacy and function of such devices. The work presented here is focused on the application of surface and analytical chemistry techniques for better understanding the interface of biological elements with silica substrates and the development a novel Bio-MEMS device for studying muscle and neuromuscular biology. A novel surface patterning technique based on the use of a polyethylene glycol (PEG) silane self-assembled monolayer (SAM) as a cytophobic surface and the amine-terminated silane diethyeletriamine (DETA) as a cytophilic surface was developed for patterning a variety of cell types (e.g. skeletal muscle, and neural cells) over long periods of time (over 40 days) with high fidelity to the patterns. This method was then used to pattern embryonic rat skeletal muscle and motor neurons onto microfabricated silicon cantilevers creating a novel biological microelectromechanical system (BioMEMS) for studying muscle and the neuromuscular junction. This device was then used to study the effect of exogenously applied substances such as growth factors and toxins. Furthermore, a whispering-gallery mode (WGM) biosensor was developed for measuring the adsorption of various proteins onto glass microspheres coated with selected silane SAMS commonly used in BioMEMS system. With this biosensor it was possible to measure the kinetics of protein adsorption onto alkylsilane SAMS, in a real-time and label-free manner.

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