GALVÃO, W. S. Obtenção de Nanopartículas Superparamagnéticas de NiFe2O4 por Síntese Hidrotérmica Assistida por Micro-Ondas. 2014. 80 f. Dissertação (Mestrado em Química) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2014. / Submitted by Daniel Eduardo Alencar da Silva (dealencar.silva@gmail.com) on 2014-11-28T21:17:43Z No. of bitstreams: 1 2014_dis_wsgalvao.pdf: 2999286 bytes, checksum: 434a8fd2bf092809356032a6419b85a3 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa(jairo@ufc.br) on 2015-11-25T11:11:39Z (GMT) No. of bitstreams: 1 2014_dis_wsgalvao.pdf: 2999286 bytes, checksum: 434a8fd2bf092809356032a6419b85a3 (MD5) / Made available in DSpace on 2015-11-25T11:11:39Z (GMT). No. of bitstreams: 1 2014_dis_wsgalvao.pdf: 2999286 bytes, checksum: 434a8fd2bf092809356032a6419b85a3 (MD5) Previous issue date: 2014 / NiFe2O4 nanoparticles were synthesized by co-precipitation method, assisted by microwave heating. The colloidal precipitate was subjected to heating at various temperatures in order to determine the optimal temperature for the synthesis and resulted in materials with good morphology and small size of crystal. Next, we studied the effect of heating time on the structural and magnetic properties of nickel ferrite. The colloidal precipitate was subjected to microwave heating, keeping the temperature constant at 160 ° C at three different times 7 , 12 and 17 minutes. The XRD patterns of the samples confirmed the formation of nanoparticles, which showed cubic structure of the inverse spinel type and good crystallinity. The crystallite size was calculated using the Scherrer equation. The variation of the magnetization as a function of applied magnetic field at room temperature was studied using a vibrating sample magnetometer (VSM), obtaining values of remanent magnetization and coercivity equal to zero , suggesting superparamagnetic behavior. Increasing the heating time (7, 12 and 17 minutes) produced an increase in the size of the crystallite (9 – 27 nm) and an increase in the saturation magnetization (31 – 45 emu/g) to the sample. Blocking temperature was found by tracing graphic of remanent magnetization versus temperature. A sample of magnetite, courtesy of Advanced Materials Group – GQMAT, suffered modification of its surface by the polymer APTES (3-aminopropil)trietoxisilano, using microwave heating. Data obtained from the (VSM), thermogravimetry (TG) and Infrared (FT-IR) confirmed the adsorption from the experiments, it was possible to construct a heating ramp efficient for the production of nanomaterials to lower synthesis temperature and shorter heating time. / Nanopartículas de NiFe2O4, foram sintetizadas pelo método da co-precipitação, assistida por aquecimento de micro-ondas. Em seguida, estudou-se o efeito do tempo de aquecimento sobre as propriedades estruturais e magnéticas da ferrita de Níquel. O precipitado coloidal foi submetido ao aquecimento, mantida a temperatura constante em 160 ºC, em três tempos diferentes 7, 12 e 17 minutos, a fim de se determinar a melhor temperatura para síntese e que resultasse em materiais com boa morfologia e pequeno tamanho de cristalito. Os difratogramas das amostras confirmaram a formação das nanopartículas, que apresentaram estrutura cúbica do tipo espinelio inverso e boa cristalinidade. O tamanho do cristalito foi calculado usando a equação de Scherrer. A variação da magnetização como uma função do campo magnético aplicado à temperatura ambiente foi estudada usando o Magnetômetro de Amostra Vibrante (VSM), obtendo valores de magnetização remanescente e coercividade igual à zero, sugerindo comportamento superparamagnético. O aumento do tempo de aquecimento (7, 12 e 17 minutos) produziu um aumento no tamanho do cristalito (8,9 – 14 nm) e um aumento na magnetização de saturação (31 – 45 emu/g) para a amostra. A temperatura de bloqueio foi encontrada traçando um gráfico de magnetização remanescente versus temperatura. A amostra de magnetita sofreu modificação de sua superfície pelo polímero APTES (3-aminopropil)-trietoxisilano, utilizando o aquecimento por micro-ondas. Os dados obtidos do VSM, termogravimetria (TG) e Infravermelho (FT-IR), confirmaram a adsorção. A partir dos experimentos realizados, foi possível construir uma rampa de aquecimento eficiente para a produção de nanomateriais.

Universidade Federal do Cearà / NanopartÃculas de NiFe2O4, foram sintetizadas pelo mÃtodo da co-precipitaÃÃo, assistida por aquecimento de micro-ondas. Em seguida, estudou-se o efeito do tempo de aquecimento sobre as propriedades estruturais e magnÃticas da ferrita de NÃquel. O precipitado coloidal foi submetido ao aquecimento, mantida a temperatura constante em 160 ÂC, em trÃs tempos diferentes 7, 12 e 17 minutos, a fim de se determinar a melhor temperatura para sÃntese e que resultasse em materiais com boa morfologia e pequeno tamanho de cristalito. Os difratogramas das amostras confirmaram a formaÃÃo das nanopartÃculas, que apresentaram estrutura cÃbica do tipo espinelio inverso e boa cristalinidade. O tamanho do cristalito foi calculado usando a equaÃÃo de Scherrer. A variaÃÃo da magnetizaÃÃo como uma funÃÃo do campo magnÃtico aplicado à temperatura ambiente foi estudada usando o MagnetÃmetro de Amostra Vibrante (VSM), obtendo valores de magnetizaÃÃo remanescente e coercividade igual à zero, sugerindo comportamento superparamagnÃtico. O aumento do tempo de aquecimento (7, 12 e 17 minutos) produziu um aumento no tamanho do cristalito (8,9 â 14 nm) e um aumento na magnetizaÃÃo de saturaÃÃo (31 â 45 emu/g) para a amostra. A temperatura de bloqueio foi encontrada traÃando um grÃfico de magnetizaÃÃo remanescente versus temperatura. A amostra de magnetita sofreu modificaÃÃo de sua superfÃcie pelo polÃmero APTES (3-aminopropil)-trietoxisilano, utilizando o aquecimento por micro-ondas. Os dados obtidos do VSM, termogravimetria (TG) e Infravermelho (FT-IR), confirmaram a adsorÃÃo. A partir dos experimentos realizados, foi possÃvel construir uma rampa de aquecimento eficiente para a produÃÃo de nanomateriais. / NiFe2O4 nanoparticles were synthesized by co-precipitation method, assisted by microwave heating. The colloidal precipitate was subjected to heating at various temperatures in order to determine the optimal temperature for the synthesis and resulted in materials with good morphology and small size of crystal. Next, we studied the effect of heating time on the structural and magnetic properties of nickel ferrite. The colloidal precipitate was subjected to microwave heating, keeping the temperature constant at 160  C at three different times 7 , 12 and 17 minutes. The XRD patterns of the samples confirmed the formation of nanoparticles, which showed cubic structure of the inverse spinel type and good crystallinity. The crystallite size was calculated using the Scherrer equation. The variation of the magnetization as a function of applied magnetic field at room temperature was studied using a vibrating sample magnetometer (VSM), obtaining values of remanent magnetization and coercivity equal to zero , suggesting superparamagnetic behavior. Increasing the heating time (7, 12 and 17 minutes) produced an increase in the size of the crystallite (9 â 27 nm) and an increase in the saturation magnetization (31 â 45 emu/g) to the sample. Blocking temperature was found by tracing graphic of remanent magnetization versus temperature. A sample of magnetite, courtesy of Advanced Materials Group â GQMAT, suffered modification of its surface by the polymer APTES (3-aminopropil)trietoxisilano, using microwave heating. Data obtained from the (VSM), thermogravimetry (TG) and Infrared (FT-IR) confirmed the adsorption from the experiments, it was possible to construct a heating ramp efficient for the production of nanomaterials to lower synthesis temperature and shorter heating time.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / The magnetic nanomaterials have attracted interest in many areas due to their unique properties and a wide range of applications. One of the most used nanoparticles is magnetite, formed of an oxide of Fe +2 and Fe +3 which has a high saturation magnetization and high surface area. These properties allow the immobilization of various molecules , such as surfactants , co - polymers , drugs and enzymes for application in biomedicine , food engineering , nanochips and biocatalysts . In the present work nanobiocatalysts were produced by immobilization of CALB (Lipase B) in superparamagnetic nanoparticles functionalized with different concentrations of APTES. The structural, morphological and magnetic properties of the samples were investigated by X- ray diffraction (XRD), Spectroscopy with Fourier Transform Infrared in Region (FTIR), Thermogravimetric Analysis (TGA), adsorption/desorption of nitrogen (BET), Magnetometer Sample Vibrant (VSM), and Analysis of Catalytic Activity (Activity derivative). The XRD showed peaks crystallographic structure of spinel for magnetite in the sample. The average particle size obtained by XRD and VSM was 10nm for magnetite and 13nm for NP/ APTES. The magnetic parameters of the samples were observed by VSM and all showed superparamagnetic behavior with a decrease in the saturation magnetization of 69 emu / g of magnetite to about 35 emu / g for the complete system . TG analyzes and FTIR revealed the presence of molecules of APTES on the surface of the nanoparticle in which were found the best values of adsorption for sample NP / APTES (1:3) and this used for the immobilization of the enzyme. Was performed analysis of the hydrolytic activity of the immobilized enzyme prepared in different media concentrations of APTES. Which showed a maximum activity of 47 U / g for NP/APTES (1:3)/CALB(200). Therefore, the potential presented nanobiocatalysts formed in reactions of industrial interest. / Os nanomateriais magnÃticos tÃm atraÃdo o interesse em muitas Ãreas, devido Ãs suas propriedades Ãnicas e uma vasta gama de aplicaÃÃes. Uma das nanopartÃculas mais utilizadas à a magnetita, formada por um Ãxido de Fe+2 e Fe+3 que tem uma alta magnetizaÃÃo de saturaÃÃo e elevada Ãrea superficial. Tais propriedades permitem a imobilizaÃÃo de vÃrias molÃculas, tais como surfactantes, co-polÃmeros, drogas e enzimas para a aplicaÃÃo no campo da biomedicina, engenharia de alimentos, nanochips e biocatalizadores. No presente trabalho foram produzidos nanobiocatalisadores atravÃs da imobilizaÃÃo de CALB(Lipase B) em nanopartÃculas superparamagnÃticas funcionalizadas com diferentes concetraÃÃes de APTES. As propriedades estruturais, magnÃticas e morfologicas das amostras foram investigadas por DifraÃÃo de Raios-X (DRX), Espectroscopia na RegiÃo do Infravermelho com Transformada de Fourier (FTIR), AnÃlise TermogravimÃtrica (TGA), AdsorÃÃo/DessorÃÃo de NitrogÃnio (BET), MagnetÃmetro de Amostra Vibrante (VSM) e AnÃlise da Atividade CatalÃtica (Atividade do Derivado). O DRX mostrou picos cristalogrÃficos da estrutura de espinÃlio para a amostra de magnetita. O tamanho mÃdio das partÃculas obtidas atravÃs de DRX e VSM foi de 10nm para magnetita, 13nm para NP/APTES/CALB. Os parÃmetros magnÃticos das amostras foram observados por VSM e todos apresentaram comportamentos superparamagnÃticos com uma diminuiÃÃo na magnetizaÃÃo de saturaÃÃo de 69 emu/g da magnetita para aproximadamente 35 emu/g para o sistema completo. As anÃlises de TG e FTIR evidenciaram a presenÃa de molÃculas de APTES na superfÃcie da nanopartÃcula na qual foram encontrados melhores valores de adsorÃÃo para a amostra NP/APTES (1:3), sendo essa utilizada para a imobilizaÃÃo da enzima. Foi realizada a anÃlise de atividade hidrolÃtica da enzima imobilizada nos diferentes suportes preparados com concentraÃÃes de APTES. A qual demonstrou uma mÃxima atividade de 47 U/g para NP/APTES(1:3)/CALB(200). Por isso, o nanobiocatalisador formado apresenta potencial em reaÃÃes de interesse industrial.

Dans cette thèse, nous présentons la détection électrochimique des herbicides, c'est-à-dire le paraquat et l'isoproturon dans des échantillons aqueux. Leur utilisation intensive est une source de contamination de l'environnement et leur toxicité constitue une menace pour la santé. La détection électrochimique est une technique prometteuse et avantageuse par rapport aux méthodes de détection conventionnelles en raison de ses propriétés telles que l'analyse rapide, la facilité d'utilisation, la rentabilité et la sensibilité élevée résultant de la modification de l'électrode de travail. Ici, nous avons modifié les électrodes modifiées avec des films minces de silice mésoporeuse pour agir comme capteurs d'herbicide. Ces électrodes ont été modifiées par un processus d'auto-assemblage assisté par électrochimie, un processus bien établi pour la modification des électrodes par notre groupe. Dans la première partie, l'adhérence du film de silice mésoporeux aux électrodes de carbone a été améliorée à l'aide d'une amine primaire qui a agi comme colle moléculaire pour une meilleure fixation de ces films à la surface des électrodes. Dans la partie suivante, ces électrodes modifiées ont été utilisées pour la détection électrochimique des herbicides susmentionnés. Les électrodes modifiées ont montré une sensibilité accrue et une limite de détection basse par rapport aux électrodes non modifiées. L'effet des différents paramètres de la solution ainsi que l'épaisseur du film et la géométrie de l'électrode ont également été étudiés et ont un impact critique sur la sensibilité du système / In this thesis, we present the electrochemical detection of herbicides i.e. paraquat and isoproturon in aqueous samples. These herbicides are used worldwide extensively for weed control in different crops. Their intensive use is a source of environmental contamination and their toxicity is a threat to Human health. Electrochemical sensing is a promising and advantageous technique as compared to conventional detection methods due to its properties such as rapid analysis, ease of operation, cost effectiveness and high sensitivity as a result of working electrode modification. Here, we modified electrodes modified with mesoporous silica thin films to act as herbicide sensors. These electrodes were modified by electrochemically assisted self-assembly process, a well-established process for electrode modification by our group. In the first part adhesion of mesoporous silica film at carbon electrodes was improved with the help of a primary amine which acted as molecular glue for better attachment of these films at electrodes surface. In the next part these modified electrodes were used for electrochemical detection of above stated herbicides. Modified electrodes showed enhanced sensitivity and low limit of detection as compared to unmodified ones. Effect of different solution parameters as well as film thickness and electrode geometry was also studied and found to have critical impact on sensitivity of the system

L’introduction des nano-charges dans le milieu des polymères donna naissance aux nanocomposites et révolutionna l’univers des matériaux. Les nanocomposites sont à l’instar des composites traditionnels, un mélange de polymère et d’une charge avec au moins une dimension nanoscopique. Dans le cadre de notre projet, nous avons travaillé avec des nanocomposites à base des polymères biodégradables : polyacidelactique et polycaprolactone, combinés avec différentes nano-argiles «kaolin et bentonite» et avec différentes nano-organo-argiles. Ces nanocomposites ont été préparés par différentes méthodes (intercalation en solution, polymérisation in situ et la méthode de la voie fondue). L’avantage de ces polymères est dans leur dégradabilité ainsi que leur biocompatibilité. Une étude des relations entre l’élaboration, la microsctructure et les propriétés physico-chimiques des nanocomposites, des argiles modifiées par 3-aminopropyltriéthoxysilane (APTES) et Bromure d’Hexadecyltriméthy ammonium (CTAB) et des argiles non traitées ont été réalisés. La polymérisation in situ et le mélange à l’état fondu sont les méthodes les plus appropriées pour obtenir une meilleure dispersion nommée exfoliation. L’étude de la capacité d’adsorption du Co (II), Cd (II), Cu (II) et Ni (II) par ces deux adsorbants bruts (kaolin et bentonite) croit considérablement avec l’augmentation du pH. Cette capacité est 2 fois et demie plus importante dans le cas de la bentonite que dans celui du kaolin. L’étude comparative des cinétiques d’adsorption, nous a révélé une cinétique rapide de l’ordre de 6 min dans le cas du cobalt, 10 min dans le cas du nickel, 15 min dans le cas du cadmium et une cinétique moyenne de l’ordre de 120 minutes pour Cu (II) aussi bien pour la bentonite que pour le kaolin. L’étude de l’adsorption du Co (II), Cd (II), Cu(II) et Ni (II) par ces matériaux (argiles brutes, argiles organiquement modifiées et nanocomposites préparés par différentes méthodes) montre que la capacité d’adsorption de ces métaux lourds est importante dans le cas de l’argile modifiée par APTES / The introduction of nano-fillers into polymers field lead to the creation of the nanocomposites. This creation is starting up a new revolution into the world of materials. Nanocomposites are similar to traditional composite of a polymer blend and filler with at least one nano-scopic dimension. In our project, we worked with nanocomposites of biodegradable polymers: polyacidlactic and polycaprolactone, combined with different nanoclays "kaolin and bentonite" and with different nano-organo-clays. These nanocomposites have been prepared by different methods (solution intercalation, in situ polymerization and melt mixture methods). The advantage of these polymers is their degradability and biocompatibility. A study of the relationship between development, microsctructure and physico-chemical properties of nanocomposites, clays modified with 3-aminopropyltriethoxysilane (APTES) and Hexadecyltriméthy ammonium bromide (CTAB) and untreated clays were made. In situ polymerization and melt mixture methods are most suitable methods to get a better dispersion named exfoliation. The study of the adsorption capacity of Co (II), Cd (II), Cu (II) and Ni (II) by these two raw adsorbents (kaolin and bentonite) increases significantly with increasing pH. This capacity is two and half times higher in the case of bentonite than in kaolin. The comparative study of adsorption kinetics, we revealed rapid kinetics of the order of 6 minutes for the Co (II), 10 min for the Ni (II), 15 min for the Cd (II) and an average kinetic order of 120 minutes for Cu (II) both for the bentonite that for kaolin. The study of the adsorption of Co (II), Cd (II), Cu (II) and Ni (II) by these materials (raw clays, organically and nanocomposites prepared by different methods) shows that the adsorption capacity of these heavy metals is important in the case modified clay by APTES

Various solution-processed methods have been employed in this work. For the synthesis of graphene, a chemical exfoliation method has been used to generate large graphene flakes in the solution phase. In addition, chemical or electro polymerization has been used for synthesizing polyanthracene, which tends to form graphene nanoribbon through cyclodehydrogenation. For the device fabrication, graphene oxide (GO) thin films were deposited from solution phase on the vapor-silanzed aminosilane surface to make semiconducting active layer or conducting electrodes. Gold nanoparticles (AuNPs) were selectively self-assembled from solution phase to pattern nanowires.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-23T13:48:58Z No. of bitstreams: 1 ErikDosSantosSilva_TESE.pdf: 6543895 bytes, checksum: 29c9b0e4741aa669a76be6f191b18cf7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-24T14:05:43Z (GMT) No. of bitstreams: 1 ErikDosSantosSilva_TESE.pdf: 6543895 bytes, checksum: 29c9b0e4741aa669a76be6f191b18cf7 (MD5) / Made available in DSpace on 2018-01-24T14:05:43Z (GMT). No. of bitstreams: 1 ErikDosSantosSilva_TESE.pdf: 6543895 bytes, checksum: 29c9b0e4741aa669a76be6f191b18cf7 (MD5) Previous issue date: 2017-08-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A pesquisa em nanocomp?sitos de pol?meros e s?lica tornou-se foco de muitos pesquisadores nos ?ltimos anos devido ?s excelentes propriedades apresentadas quando comparadas aos componentes individuais. Neste trabalho foi realizado um tratamento de modifica??o superficial da s?lica com 3-aminopropiltriet?xisilano (APTES) para incorpora??o na blenda poli(metacrilato de metila)/poli(estireno-co-acrilonitrila) (PMMA/SAN) por meio de processamento em extrusora dupla rosca. Foi avaliado o efeito da adi??o de nanopart?culas de s?lica com e sem modifica??o superficial na estrutura e propriedades da blenda PMMA/SAN, com objetivo de promover melhores propriedades mec?nicas, sem comprometer a transpar?ncia dos materiais produzidos. Os materiais foram caracterizados por medidas de ?ndice de fluidez (MFI), ensaios mec?nicos de tra??o uniaxial, flex?o em 3 pontos, dureza Rockwell M (HRM) e Shore D, impacto Izod, reometria de placas paralelas, microscopia eletr?nica de transmiss?o (MET), ensaios de abras?o e risco. Os resultados reol?gicos indicaram que houve rea??o entre as nanopart?culas de s?lica tratadas com os pol?meros puros e com a blenda PMMA/SAN, mostrando-se uma t?cnica ?til para avaliar poss?veis rea??es durante o processo de extrus?o. Os nanocomp?sitos apresentaram um decr?scimo nas propriedades de resist?ncia m?xima ? tra??o, resist?ncia ao impacto e alongamento na ruptura, se comparado a blenda PMMA/SAN, que apresentou sinergismo nas propriedades de resist?ncia m?xima ? tra??o e alongamento na ruptura. Entretanto, as propriedades dos nanocomp?sitos com nanopart?culas de s?lica modificadas foram superiores aos nanocomp?sitos sem tratamento. A adi??o de s?lica tratada promoveu um aumento no m?dulo de elasticidade, dureza, abras?o e risco dos nanocomp?sitos produzidos. / Research on nanocomposites of polymers and silica has become the focus of many researchers in recent years because of the excellent properties presented when compared to individual components. In this work a surface modification treatment of silica with 3-aminopropyltriethoxysilane (APTES) was carried out for incorporation in the poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) blend by processing in a twin screw extruder. The effect of the addition of silica nanoparticles with and without surface modification on the structure and properties of the PMMA/SAN blend was evaluated, aiming to promote better mechanical properties without compromising the transparency of the materials produced. The materials were characterized by flow index measures (MFI), mechanical tests of uniaxial traction, 3-point flexure, Rockwell M hardness (HRM) and Shore D, Izod impact, parallel plate rheometry, transmission electron microscopy (TEM), abrasion and scratch tests. The rheological results indicated that there was a reaction between the silica nanoparticles treated with the pure polymers and with the PMMA/SAN blend, showing a useful technique to evaluate possible reactions during the extrusion process. The nanocomposites showed a decrease in the properties of maximum tensile strength, impact strength and elongation at break when compared to PMMA/SAN blends, which showed synergism in the properties of maximum tensile strength and elongation at break. However, the properties of the nanocomposites with modified silica nanoparticles were superior to the nanocomposites without treatment. The addition of treated silica promoted an increase in the modulus of elasticity, hardness, abrasion and scratch of the nanocomposites produced.

La biocompatibilité d'un implant est principalement contrôlée par l'interface entre le biomatériau et le tissu environnant. Afin de contrôler cette interaction et de favoriser l'adhésion des cellules sur l'implant, nous avons créé à la surface d'alliages de titane des domaines nanométriques concentrés en séquence Arginine-Glycine-Acide Aspartique (RGD) reconnue pour ses propriétés adhésives. Après avoir modifié la chimie de surface par un agent de liaison aminosilane, nous avons utilisé les méthodes de synthèse de dendrimères ou liés des nanoparticules à l'aminosilane afin de démultiplier le nombre de amines primaires par site. Ces amines primaires étant ensuite utilisées pour attacher la séquence RGD à la surface du matériau. L'adhésion d'ostéoblastes sur les matériaux préparés a été étudié par acoustique picoseconde. / Abstract

Endothelial cells, EC, are the cell type closest to the blood stream in vessel walls. These cells can affect the origin of atherosclerosis, plaques clogging the vessels. The behaviour of EC is affected by neighbouring smooth muscle cells and shear stress from the blood flow. The aim with this thesis was to fabricate a structure for an aorta-on-a-chip that can be used to study these two parameters and their influence on EC and vascular diseases. Previous research using a two-channel system resulted in leakage and low viability of the muscle cells. A three-channel system has therefore been made to include a middle channel with the muscle cells incorporated in a gel. Cell medium is flowed in the outer channels to provide the cells with nutrition. The flow in the channel with EC has been calculated to correspond to the shear stress in an aorta. Membranes of polyethylene terephthalate and polycarbonate were used to divide the channels and both were shown to be compatible with EC. Different bonding procedures were investigated to manufacture leakage-free chips. In the study, adhesive bonding clogged the channels and the parameters for thermal bonding of COC, cyclic olefin copolymer, were not fully optimised. This made chemical bonding with layers of PDMS, polydimethylsiloxane, the best alternative. APTES, (3-Aminopropyl)triethoxysilane, treatment in addition to plasma treatment on the surfaces improved the bonding strength. Polycarbonate membranes got better results in the bonding tests than polyethylene terephthalate. The resulting aorta-on-a-chip was therefore successfully fabricated in PDMS and polycarbonate membranes using plasma and APTES treatment for bonding.

Dans le domaine de la santé, l’analyse de l'haleine expirée offre un outil simple et non invasif pour le diagnostic précoce des maladies. Les capteurs de gaz à base de SnO2 modifies semblent être des dispositifs prometteurs pour détecter les gaz polaires tels que l'ammoniac. Dans cette étude, la fonctionnalisation de la surface de SnO2 a été réalisée afin d'obtenir un capteur de gaz sensible et sélectif à l'ammoniac, qui fonctionne à température ambiante. La première étape de la fonctionnalisation est la fixation covalente d’un film de 3-aminopropyltrethoxysalane (APTES) sur SnO2 en phase vapeur ou liquide. Les caractérisations effectuées par Spectroscopie Infrarouge et Spectrométrie photoélectronique X montrent qu’une quantité plus importante d'APTES a été greffée en phase liquide hydratée. La deuxième étape consiste à fonctionnaliser le SnO2-APTES avec des molécules contenant du chlorure d'acyle avec différents groupes tel que des groupes alkyle, acide et ester. Les capteurs modifiés par des acides et des esters sont sensibles à l’ammoniac entre 0,2 et 10 ppm à température ambiante. Cependant, le SnO2 APTES modifié par l’ester s'est révélé être plus sélectif que le capteur modifié par l'acide pour l’ethanol et le mondxyde de carbone. Ces résultats impliquent que la réponse est générée par les groupes fonctionnels acide et ester, NH3 modifie le moment dipolaire de la couche moléculaire greffée, ce qui entraine une modification de la conductance de SnO2. Le fonctionnement à température ambiante est l'un des avantages de ces capteurs, tout comme leur sélectivité à l'ammoniac en regard d'autres gaz tels que l'éthanol, le monoxyde de carbone et l'acétone. / One of the major challenges in the modern era is how we can detect the disease when we are still feeling healthy via noninvasive methods. Exhaled breath analysis is offering a simple and noninvasive tool for early diagnosis of diseases. Molecularly modified SnO2 sensors seem to be promising devices for sensing polar gases such as ammonia. SnO2 surface functionalization was performed in order to obtain sensitive and selective ammonia gas sensor that operates at room temperature. The first step of functionalization is the covalently attachment of 3-aminopropyltriethoxysilane (APTES) film on SnO2 in vapor or liquid phases. The characterization performed by the Infrared Spectroscopy and X-ray Photoelectron Spectroscopy, show that more APTES were grafted by hydrous liquid phase silanization. The second step was the functionalization of APTES modified SnO2 with molecules having acyl chloride of end functional groups molecules such as alkyl, acid and ester groups. Pure SnO2 and APTES modified SnO2 sensors did not show any significant sensitivity to ammonia (0.2-100 ppm) at 25 °C. On the contrary, acid and ester modified sensors are sensitive to ammonia between 0.2 and 10 ppm at room temperature. However, ester modified SnO2 was more selective than acid modified sensor regarding the ethanol and carbon monoxide gases. Ammonia variates the attached molecular layer’s dipole moment which leads to change in SnO2 conductance. Working at ambient temperature is also one of the advantages of these sensors in addition to the selectivity to ammonia regarding other gases such as ethanol, carbon monoxide and acetone.