Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第19007号 / 工博第4049号 / 新制||工||1623 / 31958 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 辻井 敬亘 / 学位規則第4条第1項該当

For several decades, the field of magneto-optics (MO) has demonstrated applications that have impact on every day applications such as in optical data storage, magnetic field sensing, crucial for magnetoencephalography and magnetocardiography; and compact and efficient optical isolators, among others. In the past, many of these applications and the devices designed for them have heavily relied on inorganic materials. Organic materials with a high MO response represent an interesting alternative to the inorganic equivalent by not only being a more cost efficient solution, but also by allowing the user to modify a number of variables to control and optimize the MO performance depending on the application and level of performance desired. In this dissertation I discuss the MO properties of novel organic materials, starting with polythiophene, which has been of interest due to the strong relationship between its high MO performance and its lamellar structure and regioregularity. I will also be discussing another material system that provides several degrees of MO tunability: magnetite based nanocomposites. A unique and novel synthetic approach described in this dissertation yields both highly transparent and MO responsive polymer films. I will be describing a systematic approach that indicates a strong influence of the size of the nanoparticle as well as the nanoparticle concentration in the MO performance of the bulk polymer, while maintaining high optical quality with minimal scattering and absorption in the visible and near infrared. Finally, I will be discussing the implementation of both a magnetite nanocomposite and a cobalt ferrite based nanocomposite in a free space magnetic field system and demonstrate the proof-of-principle operation of a sensing system.

Forty-five Angus steers (358 kg BW) were utilized in a completely randomized block design with a 3 x 3 factorial arrangement of treatments to evaluate the hypothesis that differing dietary linolenic acid (from corn, flaxseed plus corn, or milo) and whole cottonseed (WCS) inclusion (0, 5, or 15% DM) would interact to alter fatty acid metabolism and deposition of conjugated linoleic acid (CLA) in subcutaneous (s.c.) and interfasicular (i.f.) adipose tissues, and thereby decrease carcass quality score. During the feeding period (135 d), steers receiving flaxseed or corn diets had a greater gain:feed ratio (0.119 and 0.108, respectively) than steers receiving the milo diet (0.093). Following transportation to a local abattoir and overnight starvation, there was less decrease in weight in flaxseed-fed steers (1.51%) than in steers fed the corn (2.89%) or milo diets (3.11%). Ribeye area of steers fed milo was less than that of steers fed the corn or flaxseed diets. Lipogenesis from acetate in s.c. adipose tissue was greater in steers fed flaxseed (5.42 nmol h-1 105 cells-1) than in the corn (3.10 nmol h-1 105 cells-1) or milo (1.92 nmol h-1 105 cells-1) groups. Stearoyl-CoA desaturase (SCD) activity in s.c. adipose tissue was unchanged between the 0% WCS group (88.1 nmol mg protein-1 7 min-1) and the 15% WCS group (20 nmol mg protein-1 7 min-1). The i.f. saturated fatty acid percentages increased with increasing levels of WCS. The i.f. cis-9, trans-11 CLA percentage increased with increasing WCS in the steers fed the corn diet, whereas it remained unchanged or even decreased slightly in the steers fed the flaxseed or milo-based diets. Steers fed flaxseed had a greater s.c. adipose concentration of vaccenic acid (18:1trans-11) than the steers fed milo. Steers fed flaxseed also had greater s.c. and i.f. percentages of linolenic acid (18:3, n-3) than steers fed either of the other grain sources. Increased dietary linolenic acid from flaxseed may have increased s.c. adipocyte volume by stimulating lipogenesis. These data indicate that rations formulated to provide increased levels of linolenic acid (i.e., flaxseed) will increase feed efficiency and lipogenesis from acetate without altering either the quality or composition of the beef carcasses.

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The putative peroxisome proliferator-activated receptor (PPAR) α ligand, conjugated linoleic acid (CLA) induced cytoplasmic lipid droplet (LD) formation in H4IIE rat hepatoma cells. Currently, the mechanism(s) by which CLA isomers affects hepatic LD formation is unclear. We have investigated the role of PPARα and fatty acid (FA) activation in the regulation of hepatic LD formation induced by CLA isomers [cis-9,trans-11 (c9,t11), trans-10,cis-12 (t10,c12)] and linoleic acid (LA) in an in vitro model of lipid accumulation. Dose response of c9,t11 and t10,c12 CLA isomers as well as LA in quiescent H4IIE cells was assessed by Oil Red O staining and subsequent quantification after 24 hours. LD formation was induced by the CLA isomers similar to LA in a dose-dependent manner. However, treatment with the acyl CoA synthetase (ACS) inhibitor, triacsin C, resulted in significantly reduced LD formation. A similar reduction in lipid accumulation was observed with the PPARα activator, Wy14643. Furthermore, CLA isomers promoted H4IIE viability at 60 µM but decreased viability at a higher dose of 180 µM. To further understand the role of PPARα in hepatic steatosis, we studied the level and phosphorylation of PPARα in livers of male lean and fa/fa Zucker rats fed either a control diet or fa/fa Zucker rats fed a CLA isomer (0.4% wt/wt c9,t11 or 0.4% wt/wt t10,c12) diet for 8 weeks. Immunoblotting results showed that only the t10,c12 CLA isomer significantly reduced phospho-PPARα S21 compared to the lean control (ln Ctl) and it was associated with a significant increase in the phosphorylation of p38 mitogen activated protein kinase (MAPK).These changes were not observed with the c9,t11 CLA isomer. Taken together, we have shown that CLA isomers directly induce LD formation in quiescent H4IIEs by activation of the lipid storage pathway which was significantly reduced by triacsin C or Wy14643. Also, we demonstrate for the first time that only the t10,c12 CLA isomer significantly reduced PPARα phosphorylation while it increased p38 MAPK phosphorylation. These results indicate that the anti-steatotic effects of the t10,c12 CLA isomer is associated with changes in PPARα phosphorylation and thereby its activity in a MAPK-independent manner.

Conjugated polymers are promising candidates for applications in all kinds of organic optoelectronic devices: OLEDs, organic field-effect transistors (OFETs) and organic photovoltaic cells. The main goal of this work was to investigate transport features of photogenerated electrical charge in pi-conjugated polymers by means of novel technique based on time-resolved electric field-induced second harmonic generation (TREFISH). TREFISH measurement setup was implemented in the laboratory of Molecular compounds physics, and applicability of the method has been verified. Measurements were performed on three different model polymers: methyl substituted ladder-type poly(para-phenylene) (MeLPPP), poly(fluorene-co-benzothiadiazole) (F8BT) and poly(spirobifluorene-co-benzothiadiazole) (PSF-BT), having different morphological and chemical structure. It has been found that motion of photogenerated charge carriers in π-conjugated polymer films experiences rapid dynamics after excitation. Different time domains of charge transport were distinguished. Initial fast transport of photogenerated charge carriers corresponds to the carrier motion along the single polymer chain or conjugated segment of the polymer chain. Slowest carrier motion phase is well described by the stochastic drift, which is attributed to interchain jumps and determines the macroscopic equilibrium mobility. Thus, the equilibrium mobility value is not applicable to the transport on nanometer scale up to tens of nanometers... [to full text] / Konjuguotieji polimerai kaip funkcinės medžiagos gali būti panaudoti įvairiuose prietaisuose: organiniuose šviestukuose, organiniuose lauko tranzistoriuose, organiniuose saulės elementuose. Šio darbo tikslas - nustatyti fotogeneruotų krūvininkų pernašos dėsningumus π – konjuguotuose polimeruose panaudojant naują žadinimo-zondavimo metodą pagrįstą išoriniu elektriniu lauku indukuota antrosios optinės harmonikos generacija. Pagrindinis dėmesys buvo skiriamas pernašos dinamikai. Molekulinių darinių fizikos laboratorijoje buvo įrengta matavimų schema ir įvertintas metodo tinkamumas krūvio pernašos tyrimams. Buvo atlikti krūvio pernašos matavimai trijuose skirtinguose konjuguotuosiuose polimeruose. Nustatyta, kad fotogeneruotų krūvininkų judris tuoj po sužadinimo yra daug didesnis lyginant su stacionaria judrio verte, o krūvio pernašos dinamiką lemia konjuguoto polimero struktūrinė hierarchija, krūvininkų judėjimas yra daugialypis, susidedantis iš greito judėjimo viena polimero grandine ar konjuguotais polimero grandinės segmentais ir lėto šokavimo tarp atskirų polimero grandinių Pirmą kartą detaliai išnagrinėta šviesa sugeneruotų krūvininkų pernašos dinamika konjuguotuose polimeruose. Darbo rezultatai suteikia žinių apie fundamentalius krūvininkų pernašos mechanizmus konjuguotuose polimeruose, kurios gali būti panaudotos kuriant organinius elektronikos prietaisus.

LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes. The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy. / Als Reaktion auf bestimmte äußere Stimuli ändern bestimmte wasserlösliche Polymere reversibel ihren physikalischen Zustand. Dieser Vorgang kann mithilfe von Fluorophoren, die in die Polymerstrukturen eingebaut werden und deren Fluoreszenzeigenschaften vom Polymer¬zustand abhängen, detektiert werden. Diese Idee ist der Ausgangspunkt der vorliegenden Arbeit, die sich damit beschäftigt, wie äußerlich induzierte Änderungen der Löslichkeit solcher Polymere mit kovalent gebundenen Fluorophoren in Wasser in ein deutlich messbares Fluoreszenzsignal übersetzt werden können. Dazu werden photophysikalische Phänomene wie Fluoreszenz-Resonanz¬energie¬transfer und Solvatochromie ausgenutzt. In Kombination mit einem responsiven Polymergerüst wird es möglich, verschiedene Stimuli wie Lösungs¬temperatur oder Ionenstärke, oder auch Assoziation-Dissoziation Reaktionen mit anderen Makromolekülen oder biochemische Bindungs¬reaktionen über die Änderung von Fluorezenz¬farbe bzw. –Intensität autonom mit bloßem Auge zu detektieren. Unter anderem wurde ein wässriger ratiometrischer Temperatur- und Salzsensor entwickelt, der auf der komplexen supramolekularen Struktur eines thermoresponsiven Copolymers und eines thiophenbasierten konjugierten Polyelektrolyts beruht. Die Anbindung solvato¬chromer Fluorophore erlaubte den empfindlichen Nachweis einer Temperatur¬änderung oder des Vorhandenseins von Analyten. Komplexere Phänomene wie das kompetitive Anbinden von Analyten ließen sich hochempfindlich steuern und auslesen, indem gleichzeitig die Sensitivität dieser Polymeren gegenüber der Temperatur und spezifischen Antikörpern ausgenutzt wurde. Überraschenderweise wiesen die hier untersuchten thermoresponsiven Polymere wie poly-N-isopropylacrylamid (pNIPAm) oder poly-Oligoethylenglykolmethacrylate (pOEGMA) große Unterschiede bzgl. ihrer responsiven optischen Eigenschaften auf. Dies erforderte eine ausführliche Charakterisierung des Fluoreszenz- und Aggregationsverhaltens, unter- und oberhalb des Phasenübergangs, im Bezug auf die chemische Struktur. Ein Ergebnis war, dass alle drei Polymertypen sehr ähnliche temperaturabhängige makroskopische Absorptionseigenschaften aufweisen, während sich die Eigenschaften auf molekularer Ebene, wie der Hydratisierungsgrad oder die intermolekulare Polymerkettenaggregation, bei diesen Polymeren sehr unterschiedlich. Diese Arbeit zeigt damit anhand zweier sehr etablierter thermoresponsiver Polymere, nämlich pNIPAm und pOEGMA, das die chemische Struktur entscheidend für den Einsatz dieser Polymere in fluoreszenzbasierten Sensoren ist. Diese Ergebnisse haben große Bedeutung für die gezielte Entwicklung von Polymermaterialien für fluoreszenzbasierte Assays.

The putative peroxisome proliferator-activated receptor (PPAR) α ligand, conjugated linoleic acid (CLA) induced cytoplasmic lipid droplet (LD) formation in H4IIE rat hepatoma cells. Currently, the mechanism(s) by which CLA isomers affects hepatic LD formation is unclear. We have investigated the role of PPARα and fatty acid (FA) activation in the regulation of hepatic LD formation induced by CLA isomers [cis-9,trans-11 (c9,t11), trans-10,cis-12 (t10,c12)] and linoleic acid (LA) in an in vitro model of lipid accumulation. Dose response of c9,t11 and t10,c12 CLA isomers as well as LA in quiescent H4IIE cells was assessed by Oil Red O staining and subsequent quantification after 24 hours. LD formation was induced by the CLA isomers similar to LA in a dose-dependent manner. However, treatment with the acyl CoA synthetase (ACS) inhibitor, triacsin C, resulted in significantly reduced LD formation. A similar reduction in lipid accumulation was observed with the PPARα activator, Wy14643. Furthermore, CLA isomers promoted H4IIE viability at 60 µM but decreased viability at a higher dose of 180 µM. To further understand the role of PPARα in hepatic steatosis, we studied the level and phosphorylation of PPARα in livers of male lean and fa/fa Zucker rats fed either a control diet or fa/fa Zucker rats fed a CLA isomer (0.4% wt/wt c9,t11 or 0.4% wt/wt t10,c12) diet for 8 weeks. Immunoblotting results showed that only the t10,c12 CLA isomer significantly reduced phospho-PPARα S21 compared to the lean control (ln Ctl) and it was associated with a significant increase in the phosphorylation of p38 mitogen activated protein kinase (MAPK).These changes were not observed with the c9,t11 CLA isomer. Taken together, we have shown that CLA isomers directly induce LD formation in quiescent H4IIEs by activation of the lipid storage pathway which was significantly reduced by triacsin C or Wy14643. Also, we demonstrate for the first time that only the t10,c12 CLA isomer significantly reduced PPARα phosphorylation while it increased p38 MAPK phosphorylation. These results indicate that the anti-steatotic effects of the t10,c12 CLA isomer is associated with changes in PPARα phosphorylation and thereby its activity in a MAPK-independent manner.

The synthesis and biological sensing applications of novel water soluble poly(para-phenyleneethynylene)s (PPEs) are presented. The ease of synthesis, synthetic variability, and dramatic chromicity of PPEs makes them well suited for biological and sensing applications. Molecular recognition and signal transduction can be achieved by using PPEs as sensory materials. By incorporating biological functional groups (e.g. sugars), PPEs can efficiently detect the presence of toxic heavy metals, proteins, and bacteria through either fluorescence quenching or enhancement. Rapid, precise, and convenient sensory arrays for the detection of biological analytes are possible through the formation of gold nanoparticle-PPE constructs.