The work presented in this dissertation was aimed at understanding biology's application of soft materials to enhance sensing abilities and initiate innovative bio-inspired material-based approaches for flow (fluidic and air) sensors and photo-thermal sensors. A key aim is to help strengthen this niche of functional materials science referred to, here, as bio-inspired materials in sensing roles. The work aspires to traverse the boundaries of the subject in order to provide a strong foundation for future scientific explorations of the subject. The studies presented here, include studies of flow sensing in fish and implementing a bio-mimetic approach to microfabricated flow sensors. The work also includes studies of material based signal filtering in spiders, as well as, bio-inspired photo-thermal transduction mechanisms. The capabilities of the methodology are demonstrated with successful engineering studies.

On peut imaginer dans un futur proche que des micro-robots implantés pourront suppléer la défaillance de certaines fonctions essentielles. C’est déjà le cas avec les stimulateurs cardiaques dont les piles au lithium sont bien adaptées à leur fonctionnement pendant des années de vie du patient. Cependant, pour des systèmes plus gourmands en énergie, il convient d’améliorer la longévité et la puissance volumique de ces piles. La stratégie que nous avons choisie est basée sur une approche biomimétique et deux voies ont été suivies pour créer une biopile bioinspirée : les biopiles enzymatiques génèrent un courant électrique à partir de l’oxydation de molécules organiques et la réduction d’oxygène en eau. Les biopiles à base de membranes biomimétiques génèrent un potentiel électrique à partir du transfert d’ions au travers une membrane biomimétique.Les biopiles enzymatiques, qui utilisent par exemple le glucose et l’oxygène, sont théoriquement capables de fonctionner indéfiniment car ces substrats sont toujours présents dans l’organisme. Cependant, la biocompatibilité et la performance à long terme de ces biopiles restent des verrous pour leur mise en œuvre chez l’homme. Cette thèse décrit la conception et l’implantation de nouvelles biopiles enzymatiques chez différents modèles animaux. Leur implantation constitue un véritable défi technologique et nous amenons des solutions guidées par la physiologie en abordant les problèmes de biocompatibilité mais aussi de techniques de mesure électrique.Nous sommes maintenant capables d’implanter ces biopiles chez de gros animaux en analysant en temps réel les performances de la biopile implantée.Cette thèse développe également le concept de biopile à base de membranes biomimétiques. Il s’agit d’une biopile mettant en œuvre des protéines de transport (par exemple des canaux ioniques) insérées dans des membranes biomimétiques. Nous avons démontré la faisabilité de la transformation d’un gradient de NaCl en gradient de protons. Nous avons aussi réussi à générer une différence de potentiel de 20 millivolts avec une membrane plane de 38 mm². Cette membrane biomimétique, contenant l’échangeur sodium/proton NhaA, est stable pendant plus de 15 jours. / We believe that in the near future micro-robots or artificial implanted organs can replace failing essential organs. Lithium batteries of cardiac pacemakers are well adapted to operate for years into sick patients. However, for next generation energy intensive implanted devices, longevity and volumic power of these batteries have to be improved.We chose two biomimetic approaches to create bioinspired biofuel cells: the enzymatic biofuel cells generate electrical current from the oxidation and the reduction of organic or inorganic compounds. The biomimetic biofuel cell generate an electrical potential from ion transfer across a biomimetic membrane.The enzymatic biofuel.cells, utilizing glucose and oxygen, are theorically able to work almost indefinitely as their substrates are always present in the body fluids. However, the biocompatibility and the long-term performance of these biofuel cells for a human implantation remain a real bottleneck. This thesis describes the design and the implantation of of new enzymatic biofuel cells in different animal models. The implantation of such devices is challenging and we brought creative solutions with a physiological point of view by addressing biocompatibility problems and electrical measurement techniques. We are now capable to implant these biofuel cells in big animals by analyzing the performances of the biofuel cell in real time.This thesis initiates the biomimetic biofuel cell concept. It consists in membrane transport protein (i.e ion channels) incorporated in a biomimetic membrane. The building of a biomimetic device demonstrates the transformation of a NaCl gradient into a proton gradient. We also generate a 20 mV voltage with a 38 mm² flat membrane. This biomimetic membrane containing the NhaA sodium/ proton exchanger is stable for more than two weeks.

abstract: Biological membranes are critical to cell sustainability by selectively permeating polar molecules into the intracellular space and providing protection to the interior organelles. Biomimetic membranes (model cell membranes) are often used to fundamentally study the lipid bilayer backbone structure of the biological membrane. Lipid bilayer membranes are often supported using inorganic materials in an effort to improve membrane stability and for application to novel biosensing platforms. Published literature has shown that a variety of dense inorganic materials with various surface properties have been investigated for the study of biomimetic membranes. However, literature does not adequately address the effect of porous materials or supports with varying macroscopic geometries on lipid bilayer membrane behavior. The objective of this dissertation is to present a fundamental study on the synthesis of lipid bilayer membranes supported by novel inorganic supports in an effort to expand the number of available supports for biosensing technology. There are two fundamental areas covered including: (1) synthesis of lipid bilayer membranes on porous inorganic materials and (2) synthesis and characterization of cylindrically supported lipid bilayer membranes. The lipid bilayer membrane formation behavior on various porous supports was studied via direct mass adsorption using a quartz crystal microbalance. Experimental results demonstrate significantly different membrane formation behaviors on the porous inorganic supports. A lipid bilayer membrane structure was formed only on SiO2 based surfaces (dense SiO2 and silicalite, basic conditions) and gamma-alumina (acidic conditions). Vesicle monolayer adsorption was observed on gamma-alumina (basic conditions), and yttria stabilized zirconia (YSZ) of varying roughness. Parameters such as buffer pH, surface chemistry and surface roughness were found to have a significant impact on the vesicle adsorption kinetics. Experimental and modeling work was conducted to study formation and characterization of cylindrically supported lipid bilayer membranes. A novel sensing technique (long-period fiber grating refractometry) was utilized to measure the formation mechanism of lipid bilayer membranes on an optical fiber. It was found that the membrane formation kinetics on the fiber was similar to its planar SiO2 counterpart. Fluorescence measurements verified membrane transport behavior and found that characterization artifacts affected the measured transport behavior. / Dissertation/Thesis / Ph.D. Chemical Engineering 2011

L’acné est la dermatose la plus courante dans le monde. Cette pathologie, à causes multiples, peut impliquer des traitements longs dont l’efficacité reste à améliorer. Au niveau topique, le ciblage de la surface cutanée et en particulier des foyers infectieux (impliquant notamment la bactérie P. acnes) est un axe de recherche visant un meilleur traitement de la pathologie. Ces travaux de thèse s’inscrivent dans cet objectif, et portent sur l’utilisation de particules submicroniques minéral-organiques à base d’apatites bio-inspirées pour le traitement de l’acné en vue de la vectorisation d’un antibiotique via une nouvelle formulation galénique. Dans un premier temps, les recherches se sont focalisées sur l’élaboration et la caractérisation physico-chimique de particules apatitiques préparées en présence d’un agent dispersant. Parmi les conditions testées, un protocole de référence permettant d’obtenir une suspension colloïdale de particules d’apatite de diamètre hydrodynamique moyen (DLS) de 180 nm, stabilisées à l’aide d’un polyéthylène glycol phosphonaté, a été retenu. L’analyse des particules par DRX et IRTF a mis en évidence le caractère nanocristallin biomimétique de la phase apatitique. Dans un second temps, l’adsorption d’une molécule modèle phosphatée puis d’un antibiotique – le phosphate de clindamycine (ClindP) – a été quantifiée et analysée à l’aide de différents modèles d’adsorption. Par ailleurs, la possibilité d’une incorporation d’ions biologiquement actifs (ex : antibactériens, antiinflammatoires) tels que Cu2+ et/ou Zn2+ dans l’apatite colloïdale a été établie. Dans un troisième temps, des évaluations biologiques ainsi que divers essais de suivi des particules ont été entrepris. L’interaction avec des éléments du sang – globules rouges et protéines plasmatiques – a été explorée (dans l’éventualité d’une application sur peau lésée), mettant en évidence l’excellente hémocompatibilité de ces particules colloïdales. Différentes techniques de suivi des particules ont ensuite été abordées sur membranes synthétiques et sur explants d’oreilles de porcs, telles que l’utilisation de cellules de Franz en modes statique et dynamique, ou encore la microscopie confocale Raman. Les résultats obtenus indiquent que cette dernière technique est adaptée à l’étude de la localisation cutanée de ces particules colloïdales, et montrent une accumulation de celles-ci au niveau de l’épiderme et des follicules pileux. Enfin, une étude préliminaire d’élaboration et de caractérisation d’une forme galénique (bigel) a été abordée / Acne is the most frequent dermatosis in the world. This multifaceted pathology may necessitate long-term treatments which can be improved. For a topical application, the idea of targeting the skin surface and in particular infected pilosebaceous units (involving bacteria such as P. acnes) is one approach for a better treatment of this pathology. This thesis work follows this objective, and deals with the use of submicron mineral-organic particles based on bio-inspired apatite for the treatment of acne, in view of drug delivery via a new galenic formulation. In a first stage, research was focused on the synthesis and physicochemical characterization of apatitic particles prepared in the presence of a dispersing agent. Among the tested conditions, a reference protocol was retained, allowing the obtainment of a colloidal suspension of apatite particles with a mean hydrodynamic diameter (DLS) of 180 nm, stabilized with phosphonated polyethyleneglycol. XRD and FTIR evidenced the biomimetic nanocrystalline nature of the apatitic phase. In a second stage, the adsorption of a model phosphate molecule and then of an antibiotic – clindamycin phosphate (ClindP) – was quantified and analyzed with regard to various adsorption models. Moreover, the possibility to incorporate biologically-active ions (e.g. antibacterial, antiinflammatory) such as Cu2+ and/or Zn2+ in colloidal apatite was established. In a third part, biological evaluations as well as particle follow-up experiments were performed: the interaction with blood components – red blood cells and plasma proteins – was explored (in the eventuality of application on damaged skin), evidencing the excellent hemocompatibility of these colloidal particles. Various particle follow-up techniques were then considered, involving synthetic membranes and porcine ear skin, such as the use of Franz cells in static and dynamic modes or else Raman confocal microscopy. Results indicate that the latter technique is suitable for the study of the localization of these colloidal particles within the skin, and point out their accumulation on the epidermis and hair follicles. Finally, a preliminary study was carried out on the setup and characterization of a galenic form (bigel).

La conception de biomatériaux actifs est actuellement encouragée par le manque de thérapies régénératives efficaces pour des tissus endommagés présentant une faible capacité d’autoréparation. Les progrès récents concernant les techniques de préparation de matériaux structurés (électrospinning, microfluidique) ainsi que la découverte du fort potentiel régénératif des cellules souches ont suscité un regain d’intérêt pour des projets collaboratifs à l’interface entre biologie et sciences des matériaux. Une approche prometteuse de régénération tissulaire repose donc sur la combinaison de cellules souches et de biomatériaux implantables. Des biomatériaux innovants, injectables et servants à la fois de support aux cellules et de réservoir de molécules actives telles que des protéines ou des agents de thérapie génique (Matrice Génétiquement Activée) ont été développés. Se plaçant plus particulièrement dans le contexte de l’ingénierie du cartilage, ce travail a pour objectif de développer une stratégie complémentaire concernant l’orientation de la différenciation de cellules souches mésenchymateuses (CSM) grâce au mécanisme d’interférence ARN.La principale difficulté rencontrée lors de l’utilisation d’acides nucléiques pour induire la différenciation des CSM reste leur faible capacité à traverser les membranes cellulaires, due à leur nature hydrophile et leur charge négative. De plus, les acides nucléiques sont dégradés très facilement par les nucléases extracellulaires, ce qui rend nécessaire l’utilisation d’un vecteur. Les vecteurs non-viraux sont d’excellents candidats pour des applications in vivo en raison de leur faible coût de production et leur faible immunogénicité. Toutefois, la plupart des systèmes de vectorisation trouvés dans la littérature présentent un manque de reproductibilité associé à une cytotoxicité vis-à-vis des cellules primaires. Nous souhaitions donc développer un système de transfection synthétique à la fois efficace et biocompatible. Pour cela, nous nous sommes basés sur les résultats encourageants concernant l’utilisation des micelles de complexes polyioniques (PIC) pour la transfection des cellules dendritiques. Ces micelles sont formées par complexation de deux polyélectrolytes : un copolymère à blocs double-hydrophiles (CBDH) avec un bloc anionique et un homopolymère cationique. Dans ce travail, nous avons évalué le polyoxyde d’éthylène – b – polyacide méthacrylique en tant que CBDH et la poly-L-lysine ou le polyéthylènimine en tant que polycation. L’influence des caractéristiques des composantes (asymétrie du CBDH, nature du polycation, taille des blocs, ratio de charges…) sur les propriétés physico-chimiques des micelles formées (taille, charge de surface) a d’abord été étudiée. Puis, la possibilité de complexation d’un siRNA au sein des micelles ainsi que leur stabilité en conditions physiologiques ont été évaluées. La formulation des micelles a été conçue pour permettre une dissociation des objets à un pH comparable à celui des endosomes ; ceci a été vérifié par diffusion dynamique de la lumière. Une analyse par cytométrie en flux avec un siRNA marqué TAMRA ont démontré l’internalisation effective des micelles dans les CSM. Plus important encore, l’inhibition spécifique d’un gène cible, Runx2, a été démontrée à un niveau comparable à celui d’un vecteur commercial standard, la Lipofectamine2000®. La seconde partie de la thèse a consisté en l’élaboration de microparticules. A cet effet, nous avons préparé des microsphères de collagène par un dispositif de microfluidique, et ce à partir de diverses sources de collagène (murin, porcin, bovin). Des expériences préliminaires démontrent qu’il est possible d’imprégner les micelles dans les microsphères. De même, de premiers résultats encourageants ont été obtenus quant à la capacité du système globale à assurer l’adhésion cellulaire et permettre une transfection efficace des CSM dans un environnement 3D par les micelles PIC vectorisant un siRNA anti-Runx2. / The relative lack of efficient regenerative therapies for damaged tissues with low capacity for self-repair is one major motivation for the design of new active biomaterials. Recent progress in hierarchical materials processing techniques (electrospinning, microfluidics…) and the demonstration of the strong regenerative potential of stem cells have prompted renewed interest for collaborative projects at the biology / materials science interface. The combination of stem cells and active implantable materials has emerged as a high potential approach for the regeneration of damaged tissues. In particular, injectable cell carriers also acting as a reservoir for active molecules like proteins or gene therapy agents (Gene Activated Matrices) bring about innovative solutions to current issues in the field of tissue engineering. In the context of cartilage regeneration, the main objective of this work was to investigate a complementary strategy to orient mesenchymal stem cell (MSC) fate by the use of RNA interference. One major difficulty to reach high transfection levels and efficiently direct MSC differentiation comes from the low ability of nucleic acids (NA) to cross cellular membranes, largely due to their hydrophilicity and negative charge. This, along with a strong susceptibility to extracellular nucleases, calls for efficient gene delivery vectors. Their low production cost and low immunogenic potential make non viral vectors good candidates for in vivo applications. Besides, most systems reported in the literature show reproducibility and cytotoxicity issues with primary cells that we intended to address to achieve a safe and efficient synthetic vector for MSC. Based on previous encouraging results on the transfection of dendritic cells, we chose to investigate tripartite polyionic complex (PIC) micelles. Their formation is based on the polyelectrolyte complexation of a polyanionic double-hydrophilic block copolymer (DHBC) with a cationic homopolymer. In this work, we investigated polyethylene oxide – b – polymethacrylic acid as the DHBC and Poly-L-Lysine or Polyethyleneimine as the polycation. One major part of the work was to study the influence of micelles components characteristics (block size, DHBC asymmetry, polycation nature and molecular weight, polyelectrolyte charge ratios, etc.) on the physical characteristics (dimensions, surface charge) of the obtained nanoparticles. We then studied the ability of micelles to stably complex siRNA at high loading levels, and their stability in physiological conditions. Importantly, the PIC micelles’ formulation was designed to allow for pH-triggered disassembly in acidic conditions similar to those found in endosomes, as assessed by light scattering measurements. These nanoparticles were shown to be efficiently internalized inside MSC by flow cytometry using a fluorescently labeled SiRNA-TAMRA. Most importantly, they were shown to efficiently down-regulate Runx2 mRNA in MSC, at levels similar to those reached with the gold standard Lipofectamine2000®. The second major step for the development of a GAM suited for cartilage regeneration was to elaborate injectable microparticles. To this purpose, we prepared collagen microspheres through a microfluidic-based process and with different collagen sources (murine, bovine, and porcine). Preliminary experiments show that micelles can be efficiently loaded into the microspheres. First encouraging results were also obtained regarding the ability of the created GAM to support cell adhesion, and to allow for the efficient transfection of MSC in this 3D environment, thanks to an anti-runX2 siRNA vectorized with PIC micelles. This proof-of-concept study has demonstrated that the main elements of the nano-in-micro system are ready and mostly meet the assigned requirements. This opens the way for further work to assess the ability of this GAM to effectively improve MSC chondrogenesis and ultimately cartilage repair.

Orientador: Ana Paula Rosifini Alves Claro / Coorientador: Maria Cristina Rosifini Alves Rezende / Banca: Carlos Roberto Grandini / Banca: Estevão Tomomitsu Kimpara / Banca: Mônica Beatriz Mathor / Banca: Ana Christina Alves Rezende / Resumo: Os Biomateriais Metálicos são utilizados para reforçar ou para restaurar a forma e função de tecidos duros. Os implantes e próteses são utilizados para substituir ombros, joelhos, quadris e dentes perdidos entre outros. Nos últimos anos, varias ligas de titânio para aplicações biomédicas foram avaliadas. Neste trabalho, a influência do tratamento de superfície biomimético na osseointegração de implantes dentários da liga Ti-7,5Mo foi avaliada. Os lingotes foram obtidos a partir de titânio e molibdênio utilizando um forno a arco voltaico. Eles foram submetidos a tratamento térmico e conformados a frio em prensa rotativa. Posteriormente foram confeccionados implantes (2,0 mm de diâmetro e 2,5 mm de comprimento) sob medida os quais submetidos ao tratamento de superfície biomimético. Os implantes foram inseridos e analisados histológica realizada após 28 dias. A caracterização microestrutural e mecânica da liga Ti-7,5Mo também foi realizada. Aliga Ti-7,5Mo exibiu baixo modulo de elasticidade e elevada relação resistência/modulo. O uso do tratamento de superfície biomimético promoveu um aumento da osseointegração sobre a superfície dos implantes / Abstract: Metallic biomaterials are used to reinforce or to restore form and function of hard tissues. Implants and prosthesis are used to replace shoulders, knees, hips and teeth. In the last years, several titanium alloys for biomedical applications have been studied. In the present work, influence of biomimetic surface treatment in osseointegration of Ti-7.5Mo dental implant was evaluated. Ingots were obtained from titanium and molybdenum by using an arc-melting furnace. They were submitted to heat treatment and cold worked by swaging. Then, screw-shaped implants (2.0 mm diameter by 2.5 mm length) were custom made and they were submitted biomimetic surface treatment. Implants were implanted in the rat's femur and histological analysis was realized after 28 days. Also, microstructural and mechanical properties of Ti-7.5Mo alloy were evaluated. Ti-7.5Mo showed low elasticity modulus and higher ratio strength/modulus. Results obtained suggest that Ti-7.5Mo exhibited excellent bulk properties. The use of the biomimetic surface treatment was able to promote an increase of osseointegration on surface of dental implants / Doutor

Peptídeos antimicrobianos são vistos como alternativas promissoras a serem empregadas pela iindústria farmacêutica no controle de infecções causadas por microrganismos, como também na indústria alimentícia, onde podem desempenhar papéis como conservantes naturais de alimentos. Plantaricina149 é um membro deste grupo, sendo composto por 22 resíduos de aminoácidos, com natureza catiônica e atividade inibitória sobre algumas bactérias patogênicas. Neste trabalho, foram sintetizados diferentes peptídeos análogos à Plantaricina149 para investigar suas ações sobre microrganismos (bactérias e fungos), a fim de correlacionar estes estudos com a ação lítica do peptídeo em modelos de membrana diversos (monocamadas e vesículas fosfolipídicas). A interação de Plantaricina149 com estes sistemas foi monitorada pelas espectroscopias de dicroísmo circular e fluorescência, ensaios de tensão superficial, calorimetria e ressonância plasmônica de superfície, e mostrou ser altamente específica para superfícies fosfolipídicas que apresentam densidade de cargas negativas, tais como a membrana celular de bactérias. A interação eletrostática inicial que se estabelece entre o peptídeo e os fosfolipídios é de extrema importância, sendo capaz de induzir uma estruturação helicoidal na região C-terminal do peptídeo, enquanto a região Nterminal contribui com as interações hidrofóbicas necessárias para a penetração do peptídeo nas camadas fosfolipídicas levando a ruptura das mesmas. De forma semelhante, a atividade antimicrobiana de Plantaricina149a (e alguns de seus análogos) também mostrou ser resultado das interações das duas regiões da molécula, e foi afetada com a retirada ou modificação da região N-terminal do peptídeo. Com a deleção desta região, o peptídeo passou a ter somente ação bacteriostática sobre Staphylococcus aureus e Pseudomonas aeruginosa, perdendo a capacidade bactericida. / Antimicrobial peptides are seen as promising alternatives to be employed in pharmaceutical industry for controlling infections caused by microorganisms, and also in food industry, where they can play roles as natural food preservatives. Plantaricina149 is a member of this group, constituted of 22 amino acid residues, cationic in nature and presenting inhibitory activity against some pathogenic bacteria. In this work, different Plantaricina149 analog peptides were synthesized to investigate their action against microorganisms (bacteria and fungi), with the aim of correlating these studies with the lytic action of the peptide on several membrane models (phospholipid monolayers and vesicles). The Plantaricina149 interaction with these systems was monitored by circular dichroism and fluorescence spectroscopies, surface tension assays, calorimetry and surface plasmon resonance, and showed to be highly specific to phospholipid surfaces that present negative charge density, such as the bacteria cell membrane. The initial peptide-phospholipids electrostatic interaction is extremely important, and it is capable of inducing a helical structure in the peptide C-terminal region, while the Nterminal region contributes with the hydrophobic interactions needed to the peptide penetration in the phospholipid layers and to the disruption of them. Similarly, the Plantaricina149 antimicrobial activity has also proved to be a result of the interactions from the two regions of the molecule, and it was strongly affected by the removal or modification of the peptide N-terminal region. Promoting the deletion of this region has left the peptide only with a bacteriostatic action against Staphylococcus aureus and Pseudomonas aeruginosa, removing its bactericide ability.

Dermicidina (DCD) é um gene mapeado no cromossomo 12, lócus 12q13.1, e codifica uma proteína de 110 aminoácidos, que sofre um processamento proteolítico, gerando peptídeos ativos. O peptídeo C-terminal (DCD-1L) de 48 aminoácidos tem uma carga -2, e exerce função antibacteriana e antifúngica, e o peptídeo C-terminal splice variante, denominado DCD-SV de 59 aminoácidos, tem carga neutra, e suas propriedades ainda não foram estabelecidas. Neste trabalho são apresentados os resultados da expressão, purificação e sequenciamento da DCD nativa produzida em E. coli BL21 transformada com o vetor pAE-DCD. Na segunda parte são descritas as análises físico-químicas e bioquímicas da interação dos peptídeos sintéticos DCD-1L e DCD-SV com vesículas lipídicas gigantes e vesículas unilamelar grandes sintetizadas com palmitoil-oleoil-fosfatidilcolina. As preferenciais estruturais dos peptídeos foram investigadas por espectroscopia de Dicroísmo Circular. Nossos resultados sugerem que a DCD-SV tem alta propensão para adotar uma estrutura helicoidal permitindo sua inserção e oligomerização em membranas biomiméticas, e possível formação de canais de condutância molecular. / Dermicidin (DCD) is mapped a gene on chromosome 12, locus 12q1.13 whose 110 amino acids protein is proteolytically processed to N and C-terminal peptides. The 48-amino acid C-terminal peptide (DCD-1L) has -2 net charges and display antibacterial and antifungal properties and the 59-amino acid splice variant C-terminal peptide (DCD-SV) has neutral net charge; however, its structure and biological function are unknown. Here we show the results of expression, purification and amino acid sequencing of recombinant DCD protein produced in E.coli transformed with pAE-DCD vector. We also describe the results of physical-chemical and biochemical analyses showing the visible differences between the interactions of DCD-1LL and DCD-SV synthetic peptides with giant unilamellar vesicles and large unilamellar vesciles made of palmitoyl-oleoyl phosphatidylcholine, used as biomimetic membranes. The structural preferences of peptides were analyzed by circular dichroism spectroscopy. Our results suggest that DCD-SV peptide has higher propensity to adopt helicoidal structure enabling it to insert into mimetic membranes, undergo oligomerization and formation of conductance channel.

As metaloporfirinas (MeP) cloreto de 5,10,15,20-tetra(pentafluorofenill)porfirina de manganês (III) e ferro (III) (MnIIIP e FeIIIP) foram imobilizadas em matriz de sílica híbrida mesoporosa do tipo SBA-15. Os grupos silanóis da SBA-15 foram modificados com (3-aminopropil)trietoxissilano (APTES) e (3-aminopropil)dietoximetilsilano (APDES), que após a imobilização das metaloporfirinas geraram os catalisadores FeP-APSBA, FeP-APMSBA, MnP-APSBA e MnP-APMSBA. Um terceiro tipo de material foi preparado a partir da ligação de grupos trimetilsilil (TMS) nos catalisadores FeP-APSBA e MnP-APSBA, gerando outros dois catalisadores que foram denominados FeP-APSBA-TMS e MnP-APSBA-TMS. Os materiais foram caracterizados por FTIR, RD UV-Vis, TG/TGA MEV, MET e isotermas de adsorção e dessorção de N2 (BET/BJH). Para analisar a natureza da interação solvente-superfície nos materiais, foram determinadas medidas goniométricas de energia livre de superfície. Os catalisadores foram estudados na oxidação dos substratos (Z)-ciclo-octeno e ciclo-hexano, utilizando iodosilbenzeno (PhIO) como espécie doadora de oxigênio a fim de avalia-los como biomiméticos do citocromo P450. Os parâmetros estruturais foram comparados aos resultados catalíticos frente à formação da gaiola de solvente e das espécies intermediárias de alta valência, FeIV(O)P+. e MnV(O)P e estudar como esses fatores afetam o rendimento e a seletividade das reações catalisadas. As MeP-SBAs apresentaram uma faixa de rendimento de 88 a 47 % para epoxidação de (Z)-ciclo-octeno. Já na oxidação de ciclo-hexano houve formação de 2 a 8 % de ciclo-hexanol e 2 % de ciclo-hexanona. Observou-se maior seletividade para o álcool com as FeP-SBAs. / Manganese (III) and iron (III) 5,10,15,20- tetra(pentafluorophenyl) porphyrin (MnIIIP and FeIIIP ) chloride were immobilized in mesoporous silica hybrid matrix SBA-15. Silanol groups were modified with (3-aminopropyl)triethoxysilane (APTES) and (3-aminopropyl)diethoxymethylsilane (APDES), generating catalysts called FeP-APSBA, FeP-APMSBA, MnP-APSBA and MnP-APMSBA. A third type of material was prepared from the binding trimethylsilyl groups (TMS) in FeP-APSBA and MnP- APSBA catalysts generating the other two catalysts named FeP-APSBA-TMS and MnP-APSBA-TMS. The materials were characterized by FTIR , DR UV-Vis , TG/TGA SEM , TEM and adsorption and desorption isotherms of N2 (BET/BJH) and to analyze the materials solvent - surface interaction nature the were determined goniometric measurements of surface free energy. Catalysts were evaluated for (Z)- cyclooctene and cyclohexane oxidation mediated by iodosylbenzene (PhIO) as the oxygen donor species to evaluate their catalytic activity as cytochrome P450 biomimetics. Structural parameters were compared to catalytic results related to cage solvent formation and the intermediate species high valence FeIV(O)P+. and MnV(O) P and how these factors affect the yield and selectivity of catalysts. MeP-SBA\'s reactions showed a range of 88-47 % for epoxidation (Z)-cyclooctene and cyclohexane oxidation yielding 2 to 8 % of cyclohexanol and 2 % of cyclohexanone. In the latter case was observed a higher selectivity for alcohol with FeP-SBA\'s.

A associação entre DNA de cadeia de longa e partículas catiônicas foi caracterizada por determinações de tamanho (espalhamento de luz dinâmico), análise de potencial-zeta, turbidimetria, estabilidade coloidal, microscopia de força atômica (AFM) e determinação de citotoxicidade dos arranjos contra a bactéria E. coli a partir da contagem de unidades formadoras de colônia (UFC). Partículas de poliestireno sulfato (PSS) de diversos tamanhos foram recobertas por uma bicamada de brometo de dioctadecildimetilamônio (DODAB) e entituladas partículas biomiméticas catiônicas PSS/DODAB. Estas são altamente organizadas, catiônicas e monodispersas. Em seguida, por adição de λ, T5 ou T2-DNA, os arranjos supramoleculares PSS/DODAB/DNA foram obtidos e caracterizados em função da concentração de DNA e tamanho de partícula (80-700 nm). Em baixas concentrações de DNA, foram obtidos arranjos catiônicos PSS/DODAB/DNA de boa estabilidade coloidal, polidispersidade moderada e alta citotoxicidade contra E. coli. A partir da concentração de DNA correspondente à neutralização de cargas, foram obtidos arranjos neutros ou aniônicos de baixa estabilidade coloidal, alta polidispersidade e citotoxicidade moderada. Arranjos similares a nucleossomos foram visualizados por AFM para alguns arranjos na situação de neutralização de cargas (potencial-zeta igual a zero). Estão em perspectiva experimentos com DNA plasmidial que poderão revelar o papel do tamanho de partícula, carga e polidispersidade sobre a transfecção de genes em sistemas de células-modelo / The interaction between giant bacteriophage DNA and cationic biomimetic particles was characterized from sizing by dynamic light-scattering, zeta-potential analysis, turbidimetry, colloid stability, atomic force microscopy (AFM) and determination of cytotoxicity against E. coli from colony forming unities (CFU) counting. Firstly, polystyrene sulfate (PSS) particles with different sizes were covered by a dioctadecyldimethylammonium bromide (DODAB) bilayer yielding the so called cationic biomimetic particles (PSS/DODAB). These cationic particles are highly organized, present a narrow size distribution and were obtained over a range of particle sizes. Thereafter, upon adding λ, T5 or T2-DNA to PSS/DODAB particles, supramolecular assemblies PSS/DODAB/DNA were obtained and characterized over a range of DNA concentrations and particle sizes (80-700 nm). Over the low DNA concentration range, PSS/DODAB/DNA assemblies were cationic, colloidally stable with moderate polydispersity and highly cytotoxic against E. coli. From DNA concentration corresponding to charge neutralization, neutral or anionic supramolecular assemblies PSS/DODAB/DNA exhibited low colloid stability, high polydispersity and moderate cytotoxicity. Some nucleosome mimetic assemblies were observed by AFM at charge neutralization (zetapotential equal to zero). In perspective are experiments with plasmid DNA which will possibly reveal the role of particle charge, size and polydispersity for PSS/DODAB/DNA mediated gene transfection