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The ultimate goal of this dissertation research is to enhance the protein resistant nature of poly(ethylene oxide) (PEO) or poly(ethylene glycol) by introduction of a siloxane linker and to subsequently prepare coatings which prevent surface-induced thrombosis. The hydrophobicity and flexibility of the siloxane tether should impart both amphiphilicity and conformational mobility to the PEO chain to further decrease protein adhesion. Because adsorption of plasma (blood) proteins initiates the clotting process, coating surfaces based on these new PEO-silanes should prevent or significantly diminish thrombosis. Thus, these coatings would be extremely useful for bloodcontacting medical devices such as stents, grafts, arteriorintravenous shunts, and biosensors. Novel amphiphilic PEO-silanes were prepared with systematic variations to several key structural features, including: siloxane tether length, PEO segment length, and PEO architecture. Thus, PEO-silanes were prepared having the general formulas: a-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-[PEO8-OCH3] (n = 0, 4, and 13; linear architecture) and a-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-[PEOm-OCH3]2 (n = 0, 4, and 13; m = 6 and 12 branched architecture). The reactive triethoxysilane [(EtO)3Si-] group serves as the crosslinking or grafting moiety. The PEO segment is distanced from the (EtO)3Si- group by an oligodimethylsiloxane tether which is both hydrophobic and exhibits a high degree of chain flexibility. Crosslinked silicone coatings and surfacegrafted coatings were prepared with amphiphilic linear PEO-silanes (a-c). Crosslinked silicone coatings were also prepared with branched PEO-silanes (1a-3a and 1b-3b). All coatings showed improved resistance to common plasma proteins compared to silicone coatings. Furthermore, protein adsorption generally decreased with siloxane tether length. For crosslinked PEO-modified silicone coating systems based on linear (a-c) and branched PEO-silanes (1a-3a and 1b-3b), longer tethers enhanced PEO reorganization to the film-water interface to enhance protein resistance. In the absence of surface reorganization for surface grafted coatings prepared with linear PEO-silanes, longer siloxane tethers better inhibited protein adsorption despite a moderate decrease in graft density (sigma) and decrease in surface hydrophilicity. This indicates that longer siloxane tethers enhance the configurational mobility of the PEO segments to better repel proteins.

The development of lean body mass (LBM) is closely linked to protein feeding. Along with resistance exercise protein feeding, or amino acid provision, stimulate muscle protein synthesis (MPS). Repeated stimulation of MPS above protein breakdown results in lean mass accretion. Many athletes aim to build or maintain LBM. The aim of this thesis was to better understand the relationship between LBM and protein feeding in trained individuals. This aim was studied in the applied setting and at whole body, muscle and molecular level. Chapter 2 revealed differences in total body mass and LBM between young rugby union players competing at different playing standards. Protein consumption was higher in players that played at a higher standard. The protein consumption of players at both playing standards was higher than current protein recommendations for athletes. The Under 20 (U20) rugby union players in Chapter 3 also consumed more protein than current recommendations state. Their dietary habits changed depending on their environment and they consumed more protein while in Six Nations (6N) camp compared with out of camp. Also, there were changes in dietary habits for individuals, however, those changes did not occur at the group level. Using the camp as an education tool for good nutrition habits could be advantageous. As a group, rugby union players’ body composition did not change from pre to post a 6N tournament. However, there was individual variation, which could be meaningful for the individual players. We provide evidence suggesting that in elite sport, athletes should be considered as individuals as well as part of a group if appropriate. The protein ribosomal protein S6 kinase 1 (p70S6K1) is part of the mammalian target of rapamycin complex 1 (mTORC1) pathway, which regulates MPS. The response of p70S6K1 activity was 62% greater following resistance exercise coupled with protein feeding compared with protein feeding alone in Chapter 3. P70S6K1 activity explained a small amount of the variation in previously published MPS data. The activity of the signalling protein p70S6K1 was unchanged in response to different doses of whey protein in Chapter 4 and 5. These data suggest that resistance exercise is a larger stimulus of p70S6K1 activity and when manipulating aspects of protein feeding p70S6K1 activation may be a limited measure. Consumption of 40 g of whey protein stimulated myofibrillar MPS to a greater extent than 20 g after a bout of whole body resistance exercise. The amount of LBM that the trained individual possessed did not influence this observed response. These data suggest that the amount of muscle mass exercised may influence the amount of protein required to increase MPS stimulation. For those engaging in whole body resistance exercise 20 g of protein is not sufficient to maximally stimulate MPS. The athletes in Chapters 2 and 3 of this thesis consumed more protein than current recommendations that do not take into account whole body exercise. Current post-exercise protein recommendations may no longer be optimal given this new information. Future work should directly investigate the MPS response to protein ingestion following resistance exercise engaging different amounts of muscle mass in well trained and elite populations. Identifying the protein dose required for maximal stimulation of MPS following whole body exercise would be an informative area of future research.

<p>This work focused on grafting water-soluble polymers with well-controlled properties such as tuneable polymer chain length and high graft density to improve the biocompatibility of polymer surfaces via surface-initiated atom transfer radical polymerization (s-ATRP); and on gaining improved fundamental understanding of the mechanisms and factors (e.g., graft chain length and surface density of monomer units) in protein resistance of the water-soluble grafts.</p><p>Protein-resistant polyurethane (PU) surfaces were prepared by grafting watersoluble polymers including poly(oligo(ethylene glycol) methacrylate) (poly(OEGMA)) and poly(l-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) via s-ATRP. A typical three-step procedure was used in the ATRP grafting. First, the substrate surface was treated in an oxygen plasma and reactive sites (-OH and -OOH) were formed upon exposure to air. Second, the substrate surface was immersed in 2-bromoisobutyryl bromide (BffiB)-toluene solution to form a layer of ATRP initiator. Finally, target polymer was grafted from the initiator-immobilized surface by s-ATRP with Cu(I)Br/2bpy complex as catalyst. The graft chain length was adjusted by varying the molar ratio of monomer to sacrificial initiator in solution. The modified PU surfaces were characterized by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).</p><p>Protein adsorption experiments were carried out to evaluate the protein resistance of the surfaces. Adsorption from single and binary protein solutions as well as from plasma decreased significantly after poly(OEGMA) grafting, and decreased with increasing poly(OEGMA) main chain length. Fibrinogen (Fg) adsorption on the most resistant surfaces (chain length 200 units) was in the range of 3-33 ng/cm^2, representing a reduction of more than 96% compared to the control surfaces.</p><p>OEGMA monomers with three different molecular weights (MW 300, 475, 1100 g/mol) were used to achieve different side chain lengths of poly(OEGMA). Fibrinogen (Fg) and lysozyme (Lys) were used as model proteins in adsorption experiments. The effects of side chain length as well as main chain length were then investigated. It was found that adsorption to the poly(OEGMA)-grafted PU (PU/PO) surfaces was protein size dependent. Resistance was greater for the larger protein. For grafts of a given side chain length, the adsorption of both proteins decreased with increasing polymer main chain length. For a given main chain length, the adsorption of Fg, the larger protein, was independent of side chain length. Surprisingly, however, Lys (the smaller protein) adsorption increased with increasing side chain length. A reasonable explanation is that graft main chain density decreased as monomer size and footprint on the surface increased. Protein size-based discrimination suggests that the chain density was lower than required to form layers in the "brush" regime in which protein size is expected to have little effect on protein adsorption.</p><p>In order to achieve high surface densities of ethylene oxide (EO) units, we used a sequential double grafting approach whereby the surface was grafted first with poly(2-hydroxyethyl methacrylate) (HEMA) by s-ATRP. OEGMA grafts were then grown from the hydroxyl groups on HEMA chains by a second ATRP. The effect of EO density on protein-resistant properties was then investigated. Protein adsorption on the sequentiallygrafted poly(HEMA)-poly(OEGMA) surfaces (PU/PH/PO) was not only significantly lower than on the unmodified PU as expected, but also much lower than on the PU/PO surfaces with the same poly(OEGMA) chain length. Moreover, protein adsorption decreased with increasing EO density for these grafts. On the PU/PH/PO surface with a poly(OEGMA) chain length of 100, the adsorption of Ls and Fg were reduced by ~98% and >99%, respectively, compared to the unmodified PU. Binary protein adsorption experiments showed that suppression of protein adsorption on the PU/PH/PO surfaces was essentially independent of protein size. The double-grafted OEG layers resisted both proteins equally.</p><p>The general applicability of this approach which combines oxygen plasma treatment and ATRP grafting was also studied. Various kinds of polymers such as PU, silicone hydrogel, and polydimethylsiloxane (PDMS) were chosen as substrates. Poly(MPC) grafts with different chain lengths were achieved by the three-step ATRPgrafting procedure. It was found that protein adsorption levels on the poly(MPC) grafts were significantly lower than on the respective unmodified surfaces. Protein adsorption decreased with increasing poly(MPC) chain length. Among the surfaces investigated, PU/MPC showed the highest protein resistance for a given chain length.</p> / Thesis / Doctor of Philosophy (PhD)

<p> Protein digestibility, a function of the source of amino acids consumed, can differentially affect postprandial protein anabolism at rest. We investigated the effect of ingesting whey and casein proteins, in isolation and in combination, after an acute bout of unilateral resistance exercise on muscle protein synthesis in eight healthy resistance trained men (24.4 ± 4.8 yr; 177.4 ± 4.2 cm; 85.5 ± 14.8 kg; means± SD). On three occasions, participants performed a unilateral bout of resistance exercise following which they consumed a drink containing whey, whey and casein (1:1), or casein protein. Each drink provided 10 g of essential amino acids. Mixed muscle protein fractional synthetic rate (FSR) was determined by pulse-tracer injections of L-[ring-2H5]phenylalanine and L-[15N]phenylalanine 120-180 min after protein ingestion. The pattern of amino acid appearance in the blood after consuming the protein drinks was not different. Consequently, while consumption of the protein drinks stimulated a larger increase in FSR in the exercised leg compared to the rested leg (p < 0.05), there were no differences between the drinks. Thus, while the source of amino acids may affect protein turnover at rest, this effect is not apparent after resistance exercise. Therefore, we conclude that the ingestion of whey and casein proteins, in isolation or combination, stimulates mixed muscle protein synthesis to similar degrees after an acute bout of resistance exercise.</p> / Thesis / Master of Science (MSc)

Die Immobilisierung von Oligo(ethylenglykol)-derivaten an Oberflächen von Metallen ist ein viel versprechender Ansatz, um unspezifische Adsorptionen von Proteinen, Bakterien und Zellen zu minimieren bzw. zu verhindern. Im Mittelpunkt der Arbeit stand die Entwicklung, Darstellung, Charakterisierung sowie Applikation maßgeschneiderter, self-assembly-fähiger Moleküle, die gezielt auf TiO2- und nicht auf SiO2-Oberflächen anbinden. Die resultierenden Monoschichten (SAMs) wiesen eine Biokompatibilität sowie Biofunktionalität auf. Dazu wurden neue bisher noch nicht beschriebene Moleküle entwickelt, die auf einer Kombination von funktionalisierten Oligo(ethylenglykol)-Einheiten mit Monoalkylphosphorsäure- und Alkylphosphonsäurederivaten basieren. Diese Verbindungen konnten durch die Anwendung der Self-Assembly-Technik erfolgreich aus wässriger Lösung auf TiO2-Substrate adsorbiert werden. Die hergestellten, ultradünnen monomolekularen Schichten wurden mit verschiedenen analytischen Methoden, wie Spektroskopische Ellipsometrie, winkelabhängiger XPS und SPR-Spektroskopie charakterisiert. Durch eine gezielte Anbindung an TiO2-Oberflächen und einer stabilen Ausbildung von SAMs konnten sowohl die unspezifische Proteinadsorption zurückgedrängt bzw. verhindert, als auch eine spezifische Anbindung von ausgewählten Proteinen realisiert werden. / The surface immobilization of oligo (ethylene glycol) on metals is a promising approach to minimize or prevent non-specific adsorption of proteins, bacteria and cells. The aim of this work was the design, preparation, characterization and application of tailor-made, self-assembly molecules, which are able to adsorbed selectively on TiO2 surfaces but not on SiO2. The resulting self-assembled monolayers (SAMs) had a biocompatibility and bio functionality. For this purpose new molecules have been developed, which are not described in the literature. These compounds are derivatives of monoalkyl phosphoric acids or alkyl phosphonic acids and contain a terminal functional oligo (ethylene glycol) unit. The compounds were assembled on the TiO2-surface by self-assembly technique from aqueous solution. The adsorbed layers were characterized by different analytical tools, like angle resolved XPS, spectroscopic ellipsometry and SPR-spectroscopy. The selective adsorption of SAMs on TiO2-surfaces and the formation of stable SAMs make it possible to prevent or minimize non specific protein adsorption and also to bind selected proteins via specific surface reactions.

Die Immobilisierung von Oligo(ethylenglykol)-derivaten an Oberflächen von Metallen ist ein viel versprechender Ansatz, um unspezifische Adsorptionen von Proteinen, Bakterien und Zellen zu minimieren bzw. zu verhindern. Im Mittelpunkt der Arbeit stand die Entwicklung, Darstellung, Charakterisierung sowie Applikation maßgeschneiderter, self-assembly-fähiger Moleküle, die gezielt auf TiO2- und nicht auf SiO2-Oberflächen anbinden. Die resultierenden Monoschichten (SAMs) wiesen eine Biokompatibilität sowie Biofunktionalität auf. Dazu wurden neue bisher noch nicht beschriebene Moleküle entwickelt, die auf einer Kombination von funktionalisierten Oligo(ethylenglykol)-Einheiten mit Monoalkylphosphorsäure- und Alkylphosphonsäurederivaten basieren. Diese Verbindungen konnten durch die Anwendung der Self-Assembly-Technik erfolgreich aus wässriger Lösung auf TiO2-Substrate adsorbiert werden. Die hergestellten, ultradünnen monomolekularen Schichten wurden mit verschiedenen analytischen Methoden, wie Spektroskopische Ellipsometrie, winkelabhängiger XPS und SPR-Spektroskopie charakterisiert. Durch eine gezielte Anbindung an TiO2-Oberflächen und einer stabilen Ausbildung von SAMs konnten sowohl die unspezifische Proteinadsorption zurückgedrängt bzw. verhindert, als auch eine spezifische Anbindung von ausgewählten Proteinen realisiert werden. / The surface immobilization of oligo (ethylene glycol) on metals is a promising approach to minimize or prevent non-specific adsorption of proteins, bacteria and cells. The aim of this work was the design, preparation, characterization and application of tailor-made, self-assembly molecules, which are able to adsorbed selectively on TiO2 surfaces but not on SiO2. The resulting self-assembled monolayers (SAMs) had a biocompatibility and bio functionality. For this purpose new molecules have been developed, which are not described in the literature. These compounds are derivatives of monoalkyl phosphoric acids or alkyl phosphonic acids and contain a terminal functional oligo (ethylene glycol) unit. The compounds were assembled on the TiO2-surface by self-assembly technique from aqueous solution. The adsorbed layers were characterized by different analytical tools, like angle resolved XPS, spectroscopic ellipsometry and SPR-spectroscopy. The selective adsorption of SAMs on TiO2-surfaces and the formation of stable SAMs make it possible to prevent or minimize non specific protein adsorption and also to bind selected proteins via specific surface reactions.