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F4 positive enterotoxigenic Escherichia coli (ETEC) is the most common pathogen causing neonatal diarrhea in piglets. The pathogenesis requires the attachment of ETEC to the intestinal brush border, mediated by F4 fimbria. Colostral anti-F4 antibodies and some non-immunoglobulin porcine skim milk proteins can bind F4 and prevent colonization and infection by F4-positive ETEC. Little is known, however, about the F4-binding ability of porcine milk fat globule membrane (MFGM) proteins. In addition, the knowledge of the absorption of porcine colostral proteins into the blood of neonatal piglets is limited, despite the well accepted concept that in neonatal piglets, protein absorption from the intestine is non-selective.<p> In this study, the ability of porcine MFGM proteins to bind purified F4ac (one of the three subtypes of F4 fimbriae) was investigated. Porcine MFGM proteins were first separated by 2D SDS-PAGE and subsequently identified by mass spectrometry. Overlay western Blot was then employed to demonstrate the interaction between porcine MFGM proteins and purified F4ac. Several proteins from porcine MFGM reacted with F4ac, and of these, lactadherin, butyrophilin, adipophilin, and acyl-CoA synthetase 3 reacted strongly. The biological function of these proteins in vivo was not investigated but it is possible that their interaction with F4ac positive ETEC interferes with bacterial attachment and colonization. In order to investigate protein absorption by neonatal piglets after natural suckling, the protein profiles of the plasma of pre-suckling and 24 h post-suckling neonatal piglets were studied by 2D SDS-PAGE. Those plasma proteins that increased prominently after suckling were then identified by mass spectrometry. Only immunoglobulins were unequivocally determined to be absorbed, because they were absent before suckling and present in large quantity in plasma 24 h after suckling. The absorption of other colostral proteins was either equivocal or not detectable by our detection methods. These results suggest that, unlike immunoglobulins, major non-immunoglobulin proteins in porcine colostrum may not be absorbed into systemic circulation in substantial amounts.

F4 positive enterotoxigenic Escherichia coli (ETEC) is the most common pathogen causing neonatal diarrhea in piglets. The pathogenesis requires the attachment of ETEC to the intestinal brush border, mediated by F4 fimbria. Colostral anti-F4 antibodies and some non-immunoglobulin porcine skim milk proteins can bind F4 and prevent colonization and infection by F4-positive ETEC. Little is known, however, about the F4-binding ability of porcine milk fat globule membrane (MFGM) proteins. In addition, the knowledge of the absorption of porcine colostral proteins into the blood of neonatal piglets is limited, despite the well accepted concept that in neonatal piglets, protein absorption from the intestine is non-selective.<p> In this study, the ability of porcine MFGM proteins to bind purified F4ac (one of the three subtypes of F4 fimbriae) was investigated. Porcine MFGM proteins were first separated by 2D SDS-PAGE and subsequently identified by mass spectrometry. Overlay western Blot was then employed to demonstrate the interaction between porcine MFGM proteins and purified F4ac. Several proteins from porcine MFGM reacted with F4ac, and of these, lactadherin, butyrophilin, adipophilin, and acyl-CoA synthetase 3 reacted strongly. The biological function of these proteins in vivo was not investigated but it is possible that their interaction with F4ac positive ETEC interferes with bacterial attachment and colonization. In order to investigate protein absorption by neonatal piglets after natural suckling, the protein profiles of the plasma of pre-suckling and 24 h post-suckling neonatal piglets were studied by 2D SDS-PAGE. Those plasma proteins that increased prominently after suckling were then identified by mass spectrometry. Only immunoglobulins were unequivocally determined to be absorbed, because they were absent before suckling and present in large quantity in plasma 24 h after suckling. The absorption of other colostral proteins was either equivocal or not detectable by our detection methods. These results suggest that, unlike immunoglobulins, major non-immunoglobulin proteins in porcine colostrum may not be absorbed into systemic circulation in substantial amounts.

Dans les dernières 15 ans, la recherche biomédicale a exploré en profondeur l’utilisation de nanoparticules pour la délivrance ciblée de médicaments. Parmi plusieurs matériaux étudiés, la silice mésoporeuse représente une plateforme exceptionnelle pour ce type d’applications puisque elle est biocompatible et capable d’être chargé avec une quantité élevée de médicament, tout en étant facile à synthétiser et à fonctionnaliser. La connaissance des interactions entre nanoparticules de silice et environnement biologique est nécessaire pour concevoir des vecteurs thérapeutiques efficaces et pas toxiques. Cet étude a développé une nouvelle méthode d’analyse in situ pour suivre les interactions entre silice mésoporeuse et fluides biologiques réels (sérum et sang), employant une cellule d’analyse microfluidique et l’ellipsométrie en réflexion totale interne. Nous avons ainsi réalisé le suivi dynamique de la dégradation de vecteurs models à base de silice poreuse structuré dans une solution tampon à pH physiologique et une solution concentré de protéines. Ces analyses ont permis d’évaluer l’influence de la structure poreuse, de l’adsorption de protéines sur la surface et de la vitesse du flux sur la dissolution de la silice mésoporeuse. / Dans les dernières 15 ans, la recherche biomédicale a exploré en profondeur l’utilisation de nanoparticules pour la délivrance ciblée de médicaments. Parmi plusieurs matériaux étudiés, la silice mesoporeuse représente une plateforme exceptionnelle pour ce type d’applications puisque elle est biocompatible et capable d’être chargé avec une quantité élevée de médicament, tout en étant facile à synthétiser et à fonctionnaliser .La connaissance des interactions entre nanoparticules de silice et environnement biologique est nécessaire pour concevoir des vecteurs thérapeutiques efficaces et pas toxiques. Cet étude a développé une nouvelle méthode d’analyse in situ pour suivre les interactions entre silice mesoporeuse et fluides biologiques réels (serum et sang), employant une cellule d’analyse microfluidique et l’ellipsometrie en réflexion totale interne. Nous avons ainsi réalisé le suivi dynamique de la dégradation de vecteurs models à base de silice poreuse structuré dans une solution tampon à pH physiologique et une solution concentré de protéines. Ces analyses ont permis d’évaluer l’influence de la structure poreuse, de l’adsorption de protéines sur la surface et de la vitesse du flux sur la dissolution de la silice mesoporeuse.

Current strategies for designing biomaterials involve creating materials and interfaces that interact with biomolecules, cells and tissues.  This thesis aims to investigate several bioactive surfaces, such as nanocrystalline diamond (NCD), hydroxyapatite (HA) and single crystalline titanium dioxide, in terms of material synthesis, surface functionalization and characterization. Although cochlear implants (CIs) have been proven to be clinically successful, the efficiency of these implants still needs to be improved. A CI typically only has 12-20 electrodes while the ear has approximately 3400 inner hair cells. A type of micro-textured NCD surface that consists of micrometre-sized nail-head-shaped pillars was fabricated. Auditory neurons showed a strong affinity for the surface of the NCD pillars, and the technique could be used for neural guidance and to increase the number of stimulation points, leading to CIs with improved performance. Typical transparent ceramics are fabricated using pressure-assisted sintering techniques. However, the development of a simple energy-efficient production method remains a challenge. A simple approach to fabricating translucent nano-ceramics was developed by controlling the morphology of the starting ceramic particles. Translucent nano-ceramics, including HA and strontium substituted HA, could be produced via a simple filtration process followed by pressure-less sintering. Furthermore, the application of such materials as a window material was investigated. The results show that MC3T3 cells could be observed through the translucent HA ceramic for up to 7 days. The living fluorescent staining confirmed that the MC3T3 cells were visible throughout the culture period. Single crystalline rutile possesses in vitro bioactivity, and the crystalline direction affects HA formation. The HA growth on (001), (100) and (110) faces was investigated in a simulated body fluid in the presence of fibronectin (FN) via two different processes. The HA layers on each face were analysed using different characterization techniques, revealing that the interfacial energies could be altered by the pre-adsorbed FN, which influenced HA formation. In summary, micro textured NCD, and translucent HA and FN functionalized single crystalline rutile, and their interactions with cells and biomimetic HA were studied. The results showed that controlled surface properties are important for enhancing a material’s biological performance.