Orientador: Daniela Zanchet / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T07:36:24Z (GMT). No. of bitstreams: 1 Kokumai_TathianaMidori_M.pdf: 2185484 bytes, checksum: f809cfde78398806bc98554749cf01c8 (MD5) Previous issue date: 2014 / Resumo: Nanobastões de céria (CeO2) funcionalizados com grupos amino foram utilizados como suporte em catalisadores de cobre para a reação de deslocamento gás-água (WGS). A funcionalização da superfície do óxido foi realizada visando uma melhor dispersão da fase metálica no suporte, através da interação entre o grupo amino e o precursor Cu2+, com a posterior correlação entre esta modificação e a atividade do catalisador. Utilizou-se o método hidrotérmico para a síntese dos nanobastões, que foram posteriormente funcionalizados com 3-(aminopropil)trimetoxisilano. A adição do precursor Cu2+ ao suporte foi feita via impregnação, seguida de calcinação e redução (ativação do catalisador), etapa na qual se formaram as nanopartículas metálicas (Cu0) suportadas. Comparando os catalisadores com suporte de céria pura e de céria funcionalizada, observou-se que de fato a funcionalização resultou na maior dispersão do Cu2+ na superfície. No entanto, ela causou a menor dispersão do metal (Cu0) após a redução, a diminuição da redutibilidade da céria superficial, a fragmentação dos bastões e o menor desempenho catalítico frente à reação de WGS. Visando a compreensão destes sistemas, verificou-se que a calcinação após a adição de Cu2+ na amostra funcionalizada formou uma camada de SiO2 na superfície da céria, o que diminui a atividade por reduzir as interações Cu-CeO2 (formação de Cu-O-Si), corroborando a grande influência desta interface no desempenho destes catalisadores. Além disso, a menor dispersão de Cu0 na superfície funcionalizada após a redução demonstrou a importância da céria também na estabilização da fase metálica. Desta maneira, a funcionalização da superfície se mostrou uma abordagem interessante no que se refere à dispersão do precursor metálico no suporte / Abstract: Amino functionalized ceria nanorods were explored as support on copper catalysts for the water-gas shift (WGS) reaction. The purpose of the design of a functionalized oxide surface was to obtain a better metal phase dispersion on the support provided by amino-Cu2+ interaction, in addition to further correlation between this modification and the catalyst activity. The hydrothermal method was used to synthetize the nanorods, which were subsequently functionalized with 3-(aminopropyl)trimethoxysilane. The Cu2+ precursor was added to the support by impregnation, followed by calcination and reduction (catalyst activation), when the supported metallic (Cu0) nanoparticles were formed. By comparison of the catalysts obtained with pure ceria and functionalized ceria supports it was observed that the functionalization indeed caused a greater Cu2+ dispersion on the oxide surface. However, it gave rise to a lower metal dispersion (Cu0) after reduction step, along with the decrease of surface ceria reducibility, nanorods fragmentation and inferior catalytic performance towards WGS reaction. In order to understand these systems, it was confirmed that the calcination step (after Cu2+ addition) on functionalized sample created a SiO2 layer above ceria surface, therefore lowering the activity due to the decrease of Cu-CeO2 interactions (formation of Cu-O-Si), which corroborated the great influence of Cu-CeO2 interface on the activity. Also, the lower Cu0 dispersion on the functionalized surface after reduction showed the importance of ceria on the metallic phase stabilization. Hence, the surface functionalization demonstrated to be an interesting approach to the dispersion of metal precursor on the catalyst support / Mestrado / Quimica Inorganica / Mestra em Química

Nonwoven polypropylene has been utilized broadly in various hygienic and medical textile applications because of its excellent mechanical properties, chemical resistance, and minimal expense contrast with other synthetic polymers. However, the insufficiency of surface tethering groups, including adhesion, wettability, and hydrophilicity, some applications are not convenient on nonwoven polypropylene surfaces such as dyeing, printing, attachment of antibacterial and bioactive agents. To stimulate nonwoven polypropylene surface energy, utilization of supercritical carbon dioxide technology provides a resource-efficient and environment-friendly solution compares to other commonly developed wet chemical processes and ionized gas treatment techniques. This thesis investigates the possibility of functional group endorsement from 1,2,3,4-Butanetetracarboxylic acid onto nonwoven polypropylene surface in supercritical carbon dioxide media through impregnation where supercritical carbon dioxide acts as a solvent for the monomer and swelling agent for polypropylene. Two-level three-factor full factorial with a centre point statistical model implemented where pressure ranges from 9MPa to 13MPa, temperature ranges from 60°C to 100°C, and treatment time ranges from 6 hours to 8 hours, to optimize process condition to achieve less hydrophobic surface. Ethanol used as co-solvent and concentration of 1,2,3,4-Butanetetracarboxylic acid utilized 0.4 moles/litre in this investigation. Water contact angle analysis confirms surface functionalization for each treated sample and exhibits the highest decrease in surface hydrophobicity for (11MPa, 80°C, 7hrs) process condition treated sample (contact angle, θ = 114°). Statistical analysis shows the higher significance of temperature factor (p-value 0.008) with the feasibility of selected model efficacy (R2= 0.91). FTIR-ATR analysis authenticates the existence of hydrophilic functional groups (-OH, C=O, and C-O) from 1,2,3,4-Butanetetracarboxylic acid onto nonwoven polypropylene surface. Four stages mass loss thermogram of (11MPa, 80°C, 7hrs) process condition treated sample obtained from thermogravimetric analysis (TGA) confirm impregnation of organic molecules into nonwoven polypropylene matrix. Differential scanning calorimetry (DSC) analysis shows a 7.56% decrease in crystallinity percentage of (11MPa, 80°C, 7hrs) process condition treated sample than non-treated nonwoven polypropylene. In this investigation, each process condition treated nonwoven polypropylene surfaces achieve a less hydrophobic surface due to the impregnation of hydrophilic functional groups from 1,2,3,4-Butanetetracarboxylic acid did not accomplish hydrophilic character. Analysis among carbonyl index and work of adhesion results revealed a decrease in hydrophobicity depend on the concentration of hydrophilic functional groups on polypropylene surface and at the same time rely upon the crystallinity percentage and swelling properties of nonwoven polypropylene.

Direct Laser Interference Structuring (DLIP) is a manufacturing technology capable to functionalize large areas with high-precision periodic patterns. However, for industrial use of this emerging technology, solutions must be developed for specific requirements. With the objective of optimizing Direct Laser Interference Patterning in terms of process speed, an advanced optical module was developed that permits to superimpose two laser beams obtaining the interference pattern within an elongated area (linear spot) to meet the requirements of high-speed processing. After that, the influence of the process parameters on the quality of the surface patterns produced with the developed optical assembly was determined. It could be shown that the pulse overlap, in contrast to the applied average fluence, has a significant influence on the resulting structure heights of the produced patterns. Furthermore, it became apparent that during the course of the process, the underlying physical process dynamics seem to change, which was indicated by the resulting structure heights variations over the process. The gained findings will make a contribution to improving the quality of surface patterns produced with DLIP and to enabling reliable manufacturing qualities in the future.

Characterization of 3D printed polyester scaffolds modified by nano-hydroxyapatite for bone tissue engineering

Le but de la conception d’un biomatériau est de mimer les modèles qui puissent être représentatifs de la matrice extracellulaire (MEC) existant in vivo. Cet objectif peut être atteint en associant une combinaison de cellules et des facteurs biologiques à un biomatériau sur lequel ces cellules peuvent se développer pour reconstruire le tissu natif. Dans cet étude, nous avons crée des surfaces bioactives nanostructurées en combinant la nanolithographie et la fonctionnalisation de surface, en greffant un peptide RGD ou BMP-2 (bone morphogenetic protein 2). Nous avons étudié l’effet de cette nanodistribution sur le comportement des cellules souches mésenchymateuses en analysant leur adhésion et différentiation. Nous notons que la nanodistribution des peptides induit une bioactivité qui a un impact sur l’organisation du cytosquelette, la conformation des fibres de stresse de l’actin, la maturation des adhésions focales (AFs), et le commitment des cellules souches. En particulier, l’aire, la distribution, et la conformation des AFs sont affectes par la présence des nanopatterns. En plus, le RGD et le BMP-2 changent le comportement cellulaire par des voies et des mécanismes différents en variant l’organisation des cellules souches et la maturation de leurs AFs. La nanodistribution influence de façon évidente les cellules souches en modifiant leur comportement (adhésion et différenciation) ce qui a contribué et ce qui contribuera à améliorer la compréhension des interactions des cellules avec la MEC. / The aim of biomaterials design is to create an artificial environment that mimics the in vivo extracellular matrix for optimized cell interactions. A precise synergy between the scaffolding material, bioactivity, and cell type must be maintained in an effective biomaterial. In this work, we present a technique of nanofabrication that creates chemically nanopatterned bioactive silicon surfaces for cell studies. Using nanoimprint lithography, RGD and mimetic BMP-2 peptides were covalently grafted onto silicon as nanodots of various dimensions, resulting in a nanodistribution of bioactivity. To study the effects of spatially distributed bioactivity on cell behavior, mesenchymal stem cells (MSCs) were cultured on these chemically modified surfaces, and their adhesion and differentiation were studied. MSCs are used in regenerative medicine due to their multipotent properties, and well-controlled biomaterial surface chemistries can be used to influence their fate. We observe that peptide nanodots induce differences in MSC behavior in terms of cytoskeletal organization, actin stress fiber arrangement, focal adhesion (FA) maturation, and MSC commitment in comparison with homogeneous control surfaces. In particular, FA area, distribution, and conformation were highly affected by the presence of peptide nanopatterns. Additionally, RGD and mimetic BMP-2 peptides influenced cellular behavior through different mechanisms that resulted in changes in cell spreading and FA maturation. These findings have remarkable implications that contribute to the understanding of cell-extracellular matrix interactions for clinical biomaterials applications.

L’objectif de ces travaux est d’étudier les effets d’une irradiation ultrasonore haute fréquence (500 kHz) sur la synthèse électrochimique de polymères conducteurs en milieu aqueux. Les ultrasons favorisent la réaction de polymérisation électrochimique en augmentant le transport des espèces électroactives vers l’électrode. Ils engendrent des films plus compacts, présentant une topographie plus fine et plus homogène. Les effets chimiques engendrés par la propagation de l’onde acoustique permettent un meilleur taux de dopage des films. Néanmoins, leur conductivité électrique se trouve légèrement diminuée, dû à une dégradation des chaînes polymères par l’activité cavitationelle. La possibilité de contrôler les propriétés de morphologie fut mise à profit dans différentes applications comme celles des capteurs pH potentiométriques ou des revêtements anti-corrosion. Pour de telles applications, utilisant ces films en tant que couche fonctionnelle, les surfaces obtenues en présence d’irradiation ultrasonore mènent à de meilleurs résultats. Une technique de masquage sélectif à base d’ultrasons focalisés a également été développée afin d’élaborer un substrat biphasique laissant présager d’intéressantes applications biologiques / This study deals with the effects of high frequency ultrasound (500 kHz) irradiation on the electrochemical synthesis of conducting polymers in aqueous media. Ultrasound favors electrochemical polymerization reaction by improving mass transfer of electroactive species towards the electrode. It leads to films more compact, presenting a thinner and more homogeneous topography. Chemical effects generated by the acoustic wave propagation enable a higher doping level for the films. However, their electrical conductivity is slightly reduced, due to partial degradation of polymer chains by cavitational activity. The possibility to control morphological properties was used in different applications such as potentiometric pH sensors or anti-corrosion coatings. For such applications, using these films as functional layers, the irradiated coatings lead to better results. A selective masking technique, based on focused ultrasound, has been developed as well in order to elaborate a biphased substrate permitting interesting biological applications

Les biofilms sont des communautés de microorganismes emprisonnés dans une matrice de polymères organiques extracellulaires (EPS) permettant de stabiliser ces édifices tridimensionnels. La cohésion des EPS polyanioniques dans un environnement hydraté est assurée par des microdomaines hydrophobes. La localisation de ces sites hydrophobes est très importante pour comprendre la variabilité ainsi que la réactivité des EPS. Notre travail vise la synthèse de nouvelles sondes fluorescentes hydrophiles ou amphiphiles capables de marquer les EPS. Dans ce but, nous avons synthétisé une série de nanocristaux fluorescents à coeur CdSe, appelés Quantum Dots (QDs), modifiés à leur périphérie par des ligands hydrophiles (acide 3-mercaptopropionic) ou amphiphiles (acide dihydrolipoique couplé à des acides aminés hydrophobes tels que la Leucine ou la Phénylalanine). Par microscopie confocale de fluorescence et spectroscopie de corrélation de fluorescence (FCS), nous avons montré que les QDs fonctionnalisés s'associaient fortement aux EPS des biofilms de la bactérie S. oneidensis. La distribution de ces nanoparticules dans les EPS est dépendante de la structure du ligand et de sa densité à la périphérie des QDs. Une dispersion homogène des QDs hydrophiles dans l'ensemble du biofilm et une clusterisation des QDs amphiphiles dans des microdomaines hydrophobes ont notamment été observés. Les nouvelles sondes fluorescentes développées dans ce travail permettront de suivre le développement ainsi que la réorganisation de matrices biologiques complexes telles que les biofilms. / Microorganisms predominantly live in communities, such as biofilms, in which extracellular polymeric substances (EPS) form the matrix and stabilize the three-dimensional structure. Hydrophobic microdomains allow the cohesiveness of these hydrophilic, polyanionic systems. The localization of these hydrophobic sites is very important to understand the variability and the reactivity of the EPS. The objective of our work was to engineer new fluorescent probes with amphiphilic or hydrophilic properties able to label the EPS. For that purpose, we have synthesized a series of fluorescent CdSe-core nanocrystals, also called Quantum Dots (QDs), modified at their periphery with hydrophilic (3-mercaptopropionic acid) or amphiphilic ligands (dihydrolipoic acid coupled to hydrophobic aminoacids like Leucine or Phenylalanine). Using confocal fluorescence microscopy and fluorescence correlation spectroscopy (FCS), we demonstrated that the functionalized QDs strongly associated with the EPS of S. oneidensis biofilms and allow imaging of these microbial communities. The location of these probes within the EPS was dependent on the surface ligand structure and on its density at the periphery of QDs. A homogeneous dispersion of hydrophilic QDs in the whole biofilm was observed, while amphiphilic QDs clusterized in the small hydrophobic domains. These new fluorescent probes will be of great use to understand the development and the reorganization of complex biological matrix like biofilms.

L’interaction de molécules organiques avec les surfaces semiconductrices permet de contrôler les propriétés physiques de ces dernières et ce, soit à travers une modification locale en utilisant des molécules individuelles, soit par la passivation de la surface par une mono-couche complète. Aussi, le contrôle de l’interaction moléculaire nous permet de modifier les propriétés intrinsèques des molécules à travers un découplage électronique partiel ou complet entre les orbitales moléculaires et la surface. Pour atteindre ces objectifs, cette thèse présente l’étude expérimentale de l’adsorption de molécules sur la surface semiconductrice à large gap de 6H-SiC(0001)-3x3. Les expériences ont été réalisées à l’aide d’un microscope à effet tunnel opérant dans les conditions d’Ultra-Haut Vide et de température ambiante (UHV RT-STM). Les résultats ont été comparés à des études théoriques employant des calculs selon la théorie de la fonctionnelle de la densité (DFT). Trois molécules on été étudié durant ce travail de thèse : C60, Caltrope et Trima. Les études STM et DFT montre que les molécules individuelles de C60 sont chimisorbé à la surface de carbure de silicium SiC(0001)-3x3 à travers la formation d’une seule liaison Si-C avec un seul adatome de silicium, contrairement aux autres surfaces semiconductrices où la molécule se chimisorbe en formant plusieurs liaisons. Trois sites d’adsorption par rapport à l’adatome de Si de la maille de surface ont été observés. Pour expliquer les observations STM, les forces de Van der Waals entre la molécule de C60 et les atomes de la surface voisins ont du être pris en compte dans les calculs DFT. Il a été observé aussi que les molécules de C60 forment de petits clusters même à de faibles taux de couverture ce qui indique la présence d’un état précurseur de la molécule et des interactions intermoléculaires non négligeable. La molécule de Caltrope, nouvellement synthétisée, a été étudié aussi bien sur la surface de Silicium que celle de SiC. Le dépôt de cette molécule complexe ne peut être réalisé selon la méthode d’évaporation classique sans induire sa dissociation et a donc nécessité l'emploi de techniques d’évaporation spécifiques. Nos résultats expérimentaux montrent un comportement remarquable: le dépôt de molécule individuelle est induit sur la surface de manière efficace par la pointe du STM démontrant ainsi l’idée d’imprimerie moléculaire. Suite à son adsorption sur la surface de silicium à travers une seule liaison, la molécule de Caltrope se comporte comme un moteur moléculaire activé thermiquement. La troisième molécule a être étudié est la molécule de Trima. Elle a été sélectionnée à cause de sa taille comparable à la distance des ad-atomes de silicium de la surface de SiC. La structure chimique de la molécule qui se termine par un groupement cétone rend possible la fonctionnalisation de la surface. Ceci est révélé par les calculs DFT de la densité de charge. La distribution de charge montre qu’il n’y a pas de partage entre les atomes d’oxygènes de la molécule et les ad-atomes de la surface et donc nous avons un évidence claire pour la formation d’une liaison dative. / The interaction of organic molecules with a semiconductor surface enables the physical properties of the surface to be controlled, from a local modification using individual isolated molecules to passivation using a complete monolayer. Controlling the molecular interaction also allows us to modify the intrinsic properties of the molecules by partial or complete electronic decoupling between the molecular orbitals and the surface. To this end, this thesis presents experimental studies of the adsorption of molecules on the wide band gap 6H-SiC(0001)-3×3 substrate. The experiments were performed using Ultra-High Vacuum Room Temperature Scanning Tunneling Microscopy (UHV RT STM) and the results were compared with comprehensive theoretical Density Functional Theory (DFT) calculations. Three different molecules were studied in this thesis: C60, Caltrop and Trima. The STM and DFT studies show that individual C60 fullerene molecules are chemisorbed on the silicon carbide SiC(0001)-3×3 surface through the formation of a single Si-C bond to one silicon adatom, in contrast to multiple bond formation on other semiconducting surfaces. We observed three stable adsorption sites with respect to the Si adatoms of the surface unit cell. To explain the STM observations, Van der Waals forces between the C60 molecule and the neighboring surface atoms had to be included in the DFT calculations. The C60 molecules are also observed to form small clusters even at low coverage indicating the presence of a mobile molecular precursor state and non negligible intermolecular interactions. The second newly designed Caltrop molecule was studied on both the Si and SiC surfaces. Intact adsorption of this complex organic molecule cannot be realized using classical adsorption methods and requires the use of specific evaporation techniques. Our experimental results show remarkable behavior: The STM tip efficiently deposits single molecules one at a time, demonstrating the concept of single molecule printing. After adsorption on the Si surface through one bond, the Caltrop operates as a thermally activated molecular rotor. The third molecule to be studied is the Trima molecule. This molecule was chosen because it is commensurable in size with the surface Si adatom distance. The chemical termination of the molecule with a ketone group enables the successful functionalization of the SiC surface. The Trima molecule provides a rare and clear-cut example of the formation of two dative bonds between the oxygen atoms of the carbonyl groups and the Si adatoms of the SiC surface. This is revealed by the DFT calculations of the charge density. The charge distribution shows that there is no sharing of electrons between the oxygen atoms of the molecule and the surface which is clear evidence for the formation of a dative bond.

A utilização de nanopartículas (NP) magnéticas em várias áreas da biomedicina e biotecnologia vem recebendo elevado destaque nos últimos anos, graças à versatilidade de aplicações tais como: reparo de tecidos, diagnósticos, imagens por ressonância magnética, tratamento contra o câncer, separação celular, transporte controlado de drogas, entre outras. Atualmente, as NP com potencialidade de aplicação em biomedicina baseiam-se principalmente em óxidos magnéticos de ferro, os quais apresentam comportamento superparamagnético a temperatura ambiente e baixa magnetização da ordem de 60 emu g-1. A utilização dos óxidos se baseia em duas razões principais: facilidade e versatilidade de modificação da superfície e funcionalização devido aos grupos hidroxila na superfície das NP e pela baixa toxicidade comparada às NP magnéticas metálicas. Biocompatibilidade e funcionalidade específica são obtidas geralmente pela incorporação de materiais paramagnéticas e/ou diamagnéticos na superfície das NP contribuindo para diminuir ainda mais o baixo valor de magnetização de saturação dos óxidos. Nesse contexto, é necessário o desenvolvimento de novos núcleos magnéticos com elevado valor de magnetização, próximos aos valores observados para ferro metálico (~200 emu g-1). Entretanto, esses valores são observados apenas em NP metálicos com elevada toxicidade. Assim, neste trabalho, NP magnéticas bimetálicas de FePt, CoPt e NiPt recobertas óxido de ferro ou ferritas de Co e Ni foram sintetizadas pelo processo poliol modificado combinado com a metodologia de crescimento mediado por semente. As NP obtidas apresentaram tamanho e distribuição de tamanho compatíveis para aplicações biomédicas e a magnetização de saturação dos diferentes sistemas foi intensificada quando comparada às de NP de óxidos magnético puros. Os surfactantes ácido oleico e oleilamina presentes na superfície das NP como sintetizadas foram substituídos por moléculas de APTMS (3-aminopropiltrimetoxisilano) resultando em sistemas de NP dispersáveis em água. Adicionalmente, moléculas de carboximetil-dextrana foram conjugadas com as moléculas de APTMS modificando a superfície das NP e levando a formação de sistemas de NP magnéticas biocompatíveis, com estabilidade em dispersões aquosa e resposta magnética melhorada. As NP sintetizadas apresentam, em resumo, grande potencialidade para diversas aplicações em biomedicina. / In recent years, the magnetic nanoparticles uses in many biomedical and biotechnological areas have received great attention due to their applications possibilities such as: tissue repair, diagnostics, magnetic resonance imaging, cancer treatment, cell separation, and controlled drug delivery, among others. Today, the magnetic nanoparticles applications are mainly based on magnetic iron oxides, which exhibit superparamagnetic behavior at room temperature and low saturation magnetization around 60 emu g-1. Magnetic oxide uses was based in two main reasons: easily and versatility of surface changes and functionalization due to hydroxyl groups present on the oxide nanoparticles surface, and low toxicity compared with the magnetic metallic nanoparticles. Biocompatibility and targetable functionalizations are generally obtained by paramagnetic and/or diamagnetic materials incorporations onto the nanoparticle surface contributing to decreases the already low oxide saturation magnetization. In this context, the development of new magnetic nuclei with high magnetizations values closed to the metallic iron values (~200 emu g-1) is required. However, this value is only generally observed in highly toxic metallic nanoparticles. Therefore, in this study, bimetallic magnetic nanoparticles of FePt, CoPt and NiPt coated with iron oxide and Ni- or Co-ferrites in a core-shell structure are synthesized by using the modified polyol process combined with the seed-mediated growth method. Obtained nanoparticles presented size and size distribution compatible for biomedical applications and the saturation magnetization of the different synthesized systems were enhanced compared with the pure magnetic oxide nanoparticles. Oleic acid and oleylamine present on the as-synthesized magnetic nanoparticles surface were properly changed by (3-aminopropyl)trimethoxysilane (APTMS) molecules leading to water-dispersible magnetic nanoparticles system. In addition, carboxymethyl-dextran molecules were conjugated with the APTMS molecules changing the nanoparticles surfaces and resulting in biocompatible water-soluble magnetic nanoparticles systems with improved magnetic response. These synthesized biocompatible magnetic systems present a great potential for many biomedical applications.

Le but de cette thèse a été le développement de capteurs électrochimiques en flux, basés sur l'utilisation du feutre de graphite comme électrode de travail pour l'analyse pharmaceutique et environnementale du cuivre (II) et du zinc (II), deux métaux lourds essentiels pour l'homéostasie de l'organisme humain, mais toxiques en excès. Pour la détection des ions zinciques (II), une cellule d'analyse en flux, bien adaptée pour l'utilisation du feutre de graphite utilisé comme électrode de travail a été élaborée. Les conditions analytiques ont été optimisées et ont conduit à la détection du zinc (II) avec de bonnes sensibilités. Ces résultats montrent l'intérêt de réaliser en flux l'étape de pré-concentration pour augmenter la cinétique d'électrodéposition. Nous avons réalisé une étude complète sur une électrode en feutre de graphite modifiée par réduction d'un sel de diazonium, conduisant à la formation d'un film organique ayant une forte affinité pour les ions cuivriques. L'électrode modifiée combinée avec une étape de pré-concentration en flux permet la réalisation d'un capteur d'ions Cu2+ avec une grande sensibilité et une bonne sélectivité. Nous avons développé, aussi, un capteur électrochimique en flux pour l'analyse des traces d'ions cuivriques à l'aide d'une électrode en feutre de graphite modifiée avec un récepteur capable de complexer de façon sélective les ions de cuivre (II) dans des solutions aqueuses. Enfin, nous avons testé la détection électrochimique du cuivre (II) à l'aide d'électrodes modifiées bidimensionnelles, CPE et SPE. Les résultats préliminaires montrent une bonne capacité de ces électrodes pour la complexation et la détection des ions cuivriques (II). / The scope of this thesis was the development of flow electrochemical sensors, based on the use of graphite felt as a working electrode for the pharmaceutical and environmental analysis of zinc (II) and copper (II) ions, two heavy metals essential for the homeostasis of the human organism, but toxic if found in excess. For the detection of zinc (II) ions, a custom made flow cell was developed, well suited for the use of a graphite felt as working electrode in anodic stripping voltammetry analyses. The analytical conditions were optimized, leading to the detection of zinc with good sensitivities. These results prove the capacity of the preconcentration in flow to increase the kinetics of electrodeposition. A complet study on a graphite felt electrode modified by reduction of a diazonium salt, resulting in the formation of an organic film with high affinity for copper (II) ions was performed. The modified electrode combined with a flow preconcentration step allowed the achievement of a Cu2+ sensor with high sensitivity and good selectivity. We developed, also, a flow electrochemical sensor, allowing the analysis of traces of copper (II) ions, using a graphite felt electrode modified with a ligand proved to be able to selectively complex the copper (II) in aqueous solutions. Finally, we tested the electrochemical detection of zinc (II) and copper (II) ions by using modified bi-dimensional electrodes, CPE and SPE. Preliminary results show a good capacity of these modified electrodes for the complexation and detection of the copper (II) ions.