La détection de molécules biologiques dans les environnements physiologiques est essentielle aux soins de santé et la surveillance de l'environnement. Dans ces travaux de thèse, nous étudions et utilisons des surfaces d'or pour la détection de biomolécules, avec l'inclusion de composants nanométriques-spécifiquement, des monocouches auto assemblées (SAMs) d'alcane-thiol et des coquilles d'or nanostructurées-dans l'intention d'améliorer les méthodes de détection biomoléculaire. La fonctionnalisation des surfaces d'or avec des SAMs permet un contrôle de la densité et de l'orientation des biomolécules immobilisées. En utilisant la spectroscopie infrarouge de surface, la spectroscopie de photoelectrons X (XPS) ainsi que la modélisation, utilisant la théorie de la fonctionnelle de la densité (DFT), nous avons trouvé que les SAMs à base de chaînes courtes et de chaînes longues des alcane-thiols ont eu des environnements de l'accroche des atomes de soufre différents. De plus, nous avons trouvé que l'immobilisation et la reconnaissance de protéines varie avec la longueur de la chaîne de SAMs ainsi qu'avec la présence d'un réticulant. Dans la seconde partie des travaux, nous avons synthétisé des coquilles d'or nanostructurées sur des particules magnétiques afin de combiner la séparation magnétique et la détection de biomolécules. Nous avons montré qu'elles pouvaient être utilisés comme substrats pour la spectrométrie Raman exaltée de surface (SERS). Afin d'établir une preuve de concept, nous avons réalisé des tests dans lesquels ces particules ont été utilisées pour détecter l'immobilisation d'oligonucléotides et l'hybridation avec SERS. / Detecting biomolecules in physiological environments is critical to health care and environmental monitoring. In this work, we study and use gold surfaces for biomolecule detection while incorporating nanoscale components—specifically, self-assembled monolayers (SAMs) of alkanethiols and gold nanostructured shells—with the goal of improving biomolecule detection methods. Using SAMs to functionalize gold surfaces can offer control over biomolecule binding density and orientation while still keeping the biomolecules near the sensing surface. Using surface IR spectroscopy, x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) modeling, we found that SAMs of short-chain and long-chain amine-terminated alkanethiols on gold had different sulphur binding environments. We also found that protein binding and recognition on the two different SAMs varied with SAM chain length and was also influenced by the presence of a cross-linker. In the second part of this work, we synthesized gold nanostructured shells on magnetic particles for combined separation and detection of biomolecules. We demonstrated their use as substrates for surface-enhanced Raman spectroscopy (SERS) As a proof-of-concept, we demonstrated the use of these particles to detect oligonucleotide binding and hybridization with SERS using a Raman-tagged oligonucleotide hairpin probe.

The passive particle separation method of elasto-inertial microfluidics have greatpotential in the field of physics, biology and chemistry. The objective of thisdegree project was to understand particle behavior in curved microchannels fornon-Newtonian fluids. This in order to optimize the separation of 1 µm and 2 µmparticles where the end goal is to create an efficient sample preparation method fordiagnosing sepsis. Fluorescent beads were spiked into PEO solutions of differentconcentrations and used in microfluidic PDMS-glass chips with various radii toexamine the influence of curvature and elasticity as well as the flow rate. Theresult indicated an independence of both curvature and elasticity. Reynoldsnumber and Dean number are dependent on the flow rate which results in atrade-off between a high and low flow rate. A low Reynolds number is not enoughto create Dean vortices that can be used to separate particles while a highReynolds number creates strong Dean vortices that can obstruct the focusing. Later, microfluidic silicon-glass chips were used to separate 1 µm and 2 µm beads.The 2 µm particles were able to focus in two different PEO concentrations whereasthe 1 µm particles did not have time to focus entirely. This makes it possible toseparate 2 µm particles along with some 1 µm particles towards one outlet whileleaving another outlet with only 1 µm particles. This is a promising start butfurther optimization is required before being applied to real bacteria separation. / Den passiva partikelseparationsmetoden elastisk tröghetsmikrofluidik har storapotential inom fysik, biologi och kemi. Målet med examensarbetet var att förståpartiklars förflyttning i krökta mikrokanaler för icke-newtonska vätskor. Dettagjordes för att optimera separering av 1 µm och 2 µm partiklar där slutmålet är attskapa en effektiv provberedningsmetod för att diagnostisera sepsis. Fluorescerandepartiklar tillsatta i PEO-l¨osningar av olika koncentrationer anv¨andes imikrofluidiska PDMS-glas chip med olika radier för att undersöka inverkan avkrökning och elasticitet samt flödeshastigheten. Resultatet indikerade ettoberoende av både krökning och elasticitet. Reynolds nummer och Deans nummerär beroende av flödeshastigheten vilket resulterar i en avvägning mellan en hög ochlåg flödeshastighet. Ett lågt Reynolds nummer är inte tillräckligt för att skapaDean virvlar vilket kan utnyttjas för att separera partiklar medan ett högtReynolds nummer framkallar starka Dean virvlar vilket kan hindra fokuseringen. Sedan användes mikrofluidiska kisel-glas chip för att separera 1 µm and 2 µmpartiklar. 2 µm partiklarna lyckades fokusera i två olika PEO-koncentrationermedan partiklarna av 1 µm inte fokuserade fullt ut. Detta gör det möjligt attseparera 2 µm partiklar tillsammans med ett antal 1 µm partiklar mot ett utloppsamtidigt som ett annat utlopp endast innehåller 1 µm partiklar. Det är enlovande start men ytterligare optimering krävs innan det kan tillämpas på faktiskbakterieseparation.

Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1µM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide nanoparticles reduced the cellular damages to the normal breast epithelial cell line (CRL 8798) induced by X-rays and to the Keratinocyte cell line induced by UV irradiation. Cerium oxide nanoparticles were also found to be neuroprotective to adult rat spinal cord and retinal neurons. We propose that cerium oxide nanoparticles act as free radical scavenger (via redox reactions on its surface) to decrease the ROS induced cellular damages. Additionally, UV-visible spectroscopic studies indicated that cerium oxide nanoparticles possess auto-regenerative property by switching its oxidation state between Ce3+ and Ce4+. The auto-regenerative antioxidant property of these nanoparticles appears to be a key component in all the biological applications discussed in the present study.

We developed new methods for controlling and studying microtubules (MTs) outside the complex workings of the living cell. Several surface treatments for preventing MT fouling on surfaces were analyzed and, for the first time, a self-assembled monolayer (SAM) was developed which prevented MT adsorption in the absence of passivating proteins. The morphology and thickness of the SAM was measured to determine the mechanism of formation and origin of the MT-resistant behavior. The SAM was integrated into electron beam lithography for patterning and manipulating MTs using electrophoresis. Reversible MT adsorption and patterning and alignment of single MTs were achieved. We characterized the mechanism for the MT migration under electric field with a focus on the electrodynamics of the flow cell and the forces acting on the MT, along with the time dependence of the process.

Increasing the integration density of electron device components will necessitate the use of new nanofabrication paradigms that complement and extend existing technologies. One potential approach to overcome the current limitations of electron-beam lithography may involve the use of hybrid systems, in which existing lithographic techniques are coupled with “bottom up” approaches such as supramolecular self-assembly. In this respect, biological systems offer some unique possibilities as they combine both self-organization and spatial patterning at the nanometer length scale. In particular, Surface Layer Proteins (S-layers) can facilitate high order organization and specific orientation of inorganic structures as they are two-dimensional porous crystalline membranes with regular structure at the nanometer scale. In this framework, the aim of the present work was the characterization of the S-layer of Sporosarcina ureae ATCC 13881 (SslA) with respect to its self-assembling properties and modification that would allow it to be employed as a patterning element and a new building block for nanobiotechnology. In vitro recrystallization experiments have shown that wild type SslA self-assembles into monolayers, multilayers or tubes. Factors such as initial monomer concentration, Ca2+ ions, pH of the recrystallization buffer and the presence of a silicon substrate have a strong influence on the recrystallization process. SslA monolayers proved to be an excellent biotemplate for ordered assembly of gold nanoparticle arrays. The recombinant SslA after expression and purification formed micrometer sized, crystalline monolayers exhibiting the same lattice structure as the wild type protein (p4 symmetry). This remarkable property of self-assembling has been preserved even when SslA was truncated. The deletion of both, N- and C-terminal SslA domains does not hinder self-assembly; the resulting protein is able to form extended monolayers that exhibit the p4 lattice symmetry. The central SslA-domain is self sufficient for the self-assembly. The possibility to change the natural properties of S-layers by genetic engineering techniques opens a new horizon for the tuning of their structural and functional features. The SslA-streptavidin fusion protein combines the remarkable property of self-assembling with the ligand i.e. biotin binding function. On silicon wafers, this chimeric protein recrystallized into coherent protein layers and exposes streptavidin, fact demonstrated by binding studies using biotinylated quantum dots. In this way, it can serve as a functional surface for controlled immobilization of biologically active molecules but also as a platform for the synthesis of planar arrays of quantum dots. Furthermore, the results open up exciting possibilities for construction of hybrid S-layers, structures that may ultimately promote the fabrication of miniaturized, nanosized electronic devices.

Made available in DSpace on 2014-08-20T13:32:59Z (GMT). No. of bitstreams: 1 tese_vinicius_farias_campos.pdf: 556217 bytes, checksum: 4c9dc7811c567f171aaebfafce2d2254 (MD5) Previous issue date: 2011-07-29 / Nanobiotechnology has provided new scientific and technological knowledge in distinct areas making it a priority area of research in developed and developing countries. The sperm-mediated gene transfer (SMGT) technique may become more simple, efficient and cost-effective technique for the generation of transgenic animals. The development of nanocomposites able to carry foreign DNA into the nucleus of cells with greater efficiency allows techniques such as SMGT be improved. The NanoSMGT is a technique used to generate transgenic animals in which nanotechnology is used to enhance the ability of sperm to capture exogenous DNA. The objective of this study was to determine whether cationic nanopolymer or halloysite clay nanotubes are able to transfect the exogenous DNA to unsorted and sex-sorted bovine sperm then evaluate whether these sperm are able to transmit transgene to in vitro fertilized bovine embryos. Using real-time PCR, we found that the cationic nanopolymer is capable of introducing exogenous DNA into unsorted and sex-sorted bovine sperm without negative effects to sperm motility and viability. Was also demonstrated for the first time that cationic nanopolymer or halloysite clay nanotubes are able to increase both the sperm DNA transfection of as the transmission of the transgene to bovine embryos produced in vitro. These results demonstrate that NanoSMGT can be a viable technique for producing transgenic bovine embryos. / A nanobiotecnologia tem proporcionado novos avanços científicos e tecnológicos em diversas áreas do conhecimento tornando-se assim área de pesquisa prioritária em países desenvolvidos e em desenvolvimento. A transferência gênica mediada por espermatozóides (SMGT) poderá se tornar a técnica mais simples, eficiente e com melhor custo-benefício para a geração de animais transgênicos. O desenvolvimento de nanocompósitos capazes de carrear o DNA exógeno para o interior de células com maior eficiência permite que técnicas como a SMGT sejam aperfeiçoadas. A NanoSMGT é uma técnica utilizada para a geração de animais transgênicos onde a nanotecnologia é utilizada para incrementar a habilidade dos espermatozóides em capurar o DNA exógeno. O objetivo do presente trabalho foi de verificar se nanopolímero catiônico ou nanotubos de haloisita são capazes de transfectar o DNA exógeno para o interior de espermatozóides bovinos sexados e não sexados e em seguida verificar se estes espermatozóides transfectados são capazes de gerar embriões bovinos transgênicos. Utilizando PCR em tempo real, verificou-se que o nanopolímero catiônico é capaz de introduzir o DNA exógeno em espermatozóides bovinos sexados e não sexados sem danos para a motilidade e viabilidade espermática. Também foi demonstrado pela primeira vez que o nanopolímero catiônico ou os nanotubos de haloisita são capazes de incrementar tanto a transfecção de DNA em espermatozóides como a transmissão do transgene para embriões bovinos produzidos in vitro. Estes resultados demonstram que a NanoSMGT pode ser uma técnica viável para a produção de embriões bovinos transgênicos.

No description available.

Nanofabrication techniques were used to manufacture nanometer scale protein templates. The fabrication approach employs electron beam lithography (EBL) patterning on poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) self-assembled monolayers (SAM) on Au. The PEG SAM prevented protein surface adhesion and binding sites for protein were created in the SAM by EBL. Subsequent to EBL, the patterns in the PEG SAM were backfilled with 40-nm NeutrAvidin-coated fluorescent spheres (FluoSpheres). The spontaneous and directed immobilization of the spheres from a solution to the patterns resulted in high resolution protein patterns. The FluoSpheres could be arranged in any arbitrary pattern with ultimately only one or a few FluoSpheres at each binding site. Growth dynamics and SAM morphology of PEG on Au were studied by atomic force microscopy (AFM). PEG SAMs on three types of Au with different microstructure were examined: thermally evaporated granular Au and two types of Au films produced by hydrogen flame annealing of granular Au, Au(111) and "terraced" Au (crystal orientation unknown). The different Au surfaces' substructure affected the morphology and mechanical properties of the PEG SAM. On Au(111), AFM imaging revealed monolayer formation through three distinct steps: island nucleation, island growth, and coalescence. The fine-structure of the SAM revealed dendritic island formation - an observation which can be explained by attractive intermolecular interactions and diffusion-limited aggregation. Island growth was not observed on the "terraced" Au. AFM studies of EBL patterned PEG SAMs on Au(111) revealed two different patterning mechanisms. At low doses, the pattern formation occurs by SAM ablation in a self-developing process where the feature depth is directly dose dependent. At higher doses electron beam induced deposition of material, so-called contamination writing, is seen in the ablated areas of the SAM. The balance between these two mechanisms is shown to depend on the geometry of the pattern. In addition to PEG SAMs, fibronectin monolayers on SiO2 surfaces were patterned by EBL. The areas exposed with EBL lose their functionality and do not bind anti-fibronectin. With this approach we constructed fibronectin templates and used them for cell studies demonstrating pattern dependent cell geometries and cell adhesion. / QC 20101008

In this presentation it is demonstrated that the unique magnetic properties of superparamagnetic cobalt-spinel ferrite nanoparticles can be employed in several novel applications. A method to selectively capture and remove pathogens from infected organisms to improve longevity is presented. Evidence is provided to show that automated methods using modified forms of hemofiltration or peritoneal dialysis could be used to eliminate the particle/pathogen or particle/infected cell conjugates from the organism postoperatively. It is shown that disparately functionalized nanoparticles can be used in concert as drug carrier and release mechanisms. Lastly, we provide preliminary evidence to support the use of magnetic nanoparticles for controlling reaction kinetics.

<p>Nanofabrication techniques were used to manufacture nanometer scale protein templates. The fabrication approach employs electron beam lithography (EBL) patterning on poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) self-assembled monolayers (SAM) on Au. The PEG SAM prevented protein surface adhesion and binding sites for protein were created in the SAM by EBL. Subsequent to EBL, the patterns in the PEG SAM were backfilled with 40-nm NeutrAvidin-coated fluorescent spheres (FluoSpheres). The spontaneous and directed immobilization of the spheres from a solution to the patterns resulted in high resolution protein patterns. The FluoSpheres could be arranged in any arbitrary pattern with ultimately only one or a few FluoSpheres at each binding site.</p><p>Growth dynamics and SAM morphology of PEG on Au were studied by atomic force microscopy (AFM). PEG SAMs on three types of Au with different microstructure were examined: thermally evaporated granular Au and two types of Au films produced by hydrogen flame annealing of granular Au, Au(111) and "terraced" Au (crystal orientation unknown). The different Au surfaces' substructure affected the morphology and mechanical properties of the PEG SAM. On Au(111), AFM imaging revealed monolayer formation through three distinct steps: island nucleation, island growth, and coalescence. The fine-structure of the SAM revealed dendritic island formation - an observation which can be explained by attractive intermolecular interactions and diffusion-limited aggregation. Island growth was not observed on the "terraced" Au.</p><p>AFM studies of EBL patterned PEG SAMs on Au(111) revealed two different patterning mechanisms. At low doses, the pattern formation occurs by SAM ablation in a self-developing process where the feature depth is directly dose dependent. At higher doses electron beam induced deposition of material, so-called contamination writing, is seen in the ablated areas of the SAM. The balance between these two mechanisms is shown to depend on the geometry of the pattern.</p><p>In addition to PEG SAMs, fibronectin monolayers on SiO2 surfaces were patterned by EBL. The areas exposed with EBL lose their functionality and do not bind anti-fibronectin. With this approach we constructed fibronectin templates and used them for cell studies demonstrating pattern dependent cell geometries and cell adhesion.</p>