Investigou-se o efeito do \"caráter iônico\" de interfaces zwitteriônicas, formalmente neutras, representadas por micelas e vesículas obtidas de monômeros com cabeça hidrofílica dipolar, nas propriedades de acumulação e troca de espécies iônicas. Os sistemas estudados incluíram, micelas de 1-(N-hexadecil-N,N-dimetilamônio) propanossulfonato (HPS), Hexadecil fosforil colina (C16PN), 3-hexadecil glicerofostidil colina (lisoPC) e vesículas de fosfatidil colina (PC). O estudo da ligação e troca iônica nestas interfaces foi monitorado a partir de efeitos sobre reações prototrópicas de sondas como a 8-hidroxi-1,3,6-pirenotrisulfonato de sódio (piranina). Observou-se a ligação crescente da piranina na seguinte ordem lisoPC < C16PN < HPS e troca iônica com sais adicionados (função do ânion) na ordem inversa, isto é, lisoPC &gt; C16PN &gt; HPS. Estudos de reprotonação de 1 e 2 naftóis incluídos nestes agregados, via salto de pH induzido por laser, revelaram um perfil de concentração de prótons inverso àquele das cargas do dipolo, isto é, concentração nos polos negativos e exclusão nos positivos. Este resultados foram ainda reforçados por estudos de excitação de volume, via espalhamento de luz, com micelas de HPS em função de sal adicionado. A partir destes resultados propôs-se um modelo de capacitor esférico imerso em meio eletrolítico para estas interfaces, o qual se mostrou bastante versátil na análise e previsão de resultados experimentais. Em suma, estabeleceu-se no presente trabalho a visão de que interfaces dipolares são geradoras de assimetria iônica na circunvizinhança da interface, assimetria esta de polaridade invertida àquela do dipolo radialmente disposto à interface. A generalidade deste modelo pode ser extrapolado para outras interfaces e colaborar na compreensão de diversos processos que dependem da acumulação e troca iônica. / The effect of ionic domains of formally neutral zwitterionic interfaces, represented by micelles and vesicles obtained with dipolar headgroups amphiphiles, on the binding and exchange of ionic species were investigated. The systems studied included: aqueous micelles of 1-(N-hexadecyl-N,N-dimethylammonio) Propane Sulfonate (HPS), Hexadecyl Phosphoryl Choline (C16PN), and 1-hexadecylglycerophostidyl Choline (lisoPC) and vesicles of Phosphatidylcholine (PC). Binding and ion-exchange processes were assessed from the effect of these agreggates on prototropic reactions of probes such as 8-hydroxy-1,3,6-pyrenetrisulfonate pyranine). Binding of pyranine increased in the following order lisoPC < C16PN < HPS. The effectiveness of anion dependent salt displacement of the probe from the aggregates was opposite to that of affinities, i.e. lisoPC &gt; C16PN &gt; HPS. Laser pH jump studies with 1 and 2 naphtols incorporated in these aggregates revealed a proton concentration profile inverse to that of the charged dipole, that is, accumulation in the region vicinal to the negatively charged group and exclusion from the positive end of the dipole. This finding were substantiated by HPS micelle excluded volume data, obtained from light scattering studies as function of added salt. A model of a spherical capacitor immersed in an electrolyte media for these interfaces was proposed. This model accounts for satisfactorily the observed characteristics of these interfaces. The model establishes that dipolar interfaces generate ionic asymmetries in the neighborhood of the interface that opposes the radially extended monomer dipole. The generality of the model can be very helpful in the analysis and understanding of several processes occurring in/at zwitterionic interfaces.

Lipossomos de cloreto de dioctadecildimetilamonio (DODAC) com 0,51&#181; de diâmetro externo médio e transição de fase ocorrendo em uma faixa estreita de temperaturas (0,5-1,0&#176;C) foram obtidos por vaporização de clorofórmio e comparados com vesículas sonicadas de DODAC (cerca de 250 &#197; de diâmetro externo). Sacarose foi impermeante através de lipossomos grandes de DODAC ou de vesículas sonicadas de DODAC podendo ser utilizada para determinações de volume interno em ambas as preparações. Volume interno aparente para lipossomos grandes de DODAC foi 9,7 &#177; 1,3 1/mol e para vesículas sonicadas de DODAC, 0,33 &#177; 0,20 1/mol (adsorção de sacarose à bicamada de, respectivamente, 0,64 &#177; 0,30 e 0,20 &#177; 0,08 1/mol). Lipossomos grandes de DODAC comportaram-se como osmômetros em relação à sacarose e ao KCl (0-50mM KCl). Já as vesículas sonicadas de DODAC foram osmoticamente não-responsivas em relação à sacarose, floculando em presença de KCl. Essa não-responsividade osmótica foi interpretada como decorrente da presença única e exclusiva de água de hidrataçao no compartimento aquoso interno das vesículas sonicadas. Outras propriedades de lipossomos grandes de DODAC foram análogas às apresentadas por lipossomos de fosfolípides. Permeabilidades relativas (KCl como referência incorporado ao compartimento aquoso interno) do NaCl, HCl e sacarose foram similares às descritas para lipossomos de fosfatidilcolina; NaCl e sacarose sendo tão impermeantes quanto o KCl e HCl, sendo ligeiramente mais permeante que o KCl. Nas vizinhanças da temperatura de transição de fase, ocorreu um acentuado aumento da velocidade inicial de encolhimento e a extensão total de encolhimento chegou a um mínimo. A comparaçao de algumas propriedades físicas e funcionais de vesículas sonicadas e de lipossomos grandes de DODAC permitiu concluir que lipossomos grandes de DODAC constituem um modelo mais adequado para estudos de transporte. Adicionalmente, o método de vaporização de clorofórmio foi testado para o dihexadecilfosfato de Na+ (DCP) sendo obtidas dispersões homogêneas desse anfifílico capazes de incorporar um volume de 13 &#177; 4 1/mol e de responderem como osmômetros a gradientes osmóticos de sacarose, um soluto que praticamente nao é adsorvido à bicamada de DCP e que resultou impermeante através da mesma. / Dioctadecyldimethylammonium chloride (DODAC) liposomes with 0.51&#181; mean external diameter and sharp phase transitions were obtained by chloroform vaporization and compared with (small) sonicated DODAC vesicles. Sucrose was impermeant through large DODAC liposomes and sonicated vesicles and was used for internal volume determinations. The apparent internal volumes for large DODAC liposomes and sonicated DODAC vesicles were, respectively, 9.7 &#177; 1.3 and 0.33 ± 0.20 1/mol. (External sucrose adsorption were, respectively, 0.64 &#177; 0.30 and 0.20 &#177; 0.08 l/mol). Ideal osmometer behaviour towards KCl over the 0-50mM concentrations range and towards sucrose were observed only for large DODAC liposomes. Sonicated DODAC vesicles were osmotically non responsive towards sucrose and floculate with KCl. Other properties of large DODAC liposomes closely resembled those of phospholipid liposomes. At temperatures near the phase transition temperature, a steep increase in the initial shrinkage rate and a minimum for the total extent of shrinkage occured. Relative permeabilities (KCl as reference entrapped inside) to NaCl, HCl and sucrose were similar to those of phosphatidyl choline liposomes. NaCl and sucrose were as impermeant as KCl, and HCl slighthly more permeant than KCl. Large DODAC liposomes are proposed as an adequate synthetic membrane model, in contrast to sonicated DODAC vesicles. In addition, the chlroform vaporization method was tested for sodium dihexadecylphosphate (DCP). Large DCP liposomes were demonstrated to be impermeant towards sucrose entrapping 13 ± 4 l/mol and behaving as an osmometer towards this solute.

Diss. (sammanfattning) Umeå : Univ., 2009. / Härtill 4 uppsatser.

No description available.

Made available in DSpace on 2014-07-29T15:07:11Z (GMT). No. of bitstreams: 1 Dissertacao_Marcos fisica.pdf: 953271 bytes, checksum: 27094fd5d8fb314f0df53abdef0bdb38 (MD5) Previous issue date: 2009-04-15 / The Ferromagnetic Resonance (FMR) technique at the X-band (~ 9.70 GHz) and Q-band (~ 34.0 GHz) was used to study the magnetic properties of NiO/Co, NiO/Py and Py/FeMn bilayers, and Co/NiO/Co trilayers with different thicknesses, deposited by dc magnetron sputtering technique in the presence of a 400 Oe magnetic field. The FMR experiments were all done at room temperature using a high sensitivity Bruker ESP-300 spectrometer, with static scanning field and usual modulation and phase sensitive detection techniques. The angular dependence of the inplane resonance field allows the measurement of the exchange bias field for some NiO/Py bilayers and the uniaxial anisotropy of the Co layer of NiO/Py bilayers and Co/NiO/Co trilayers. The value of the exchange bias field of the NiO/Py bilayers varies from 29 Oe to 123 Oe while the uniaxial anisotropy field of the Co layer, varies from 5 to 45 Oe. For Co/NiO/Co trilayers, the Co in-plane uniaxial anisotropy field varies from 34 to 216 Oe. The out-of-plane angular dependence of the resonance field allows the measurement of the effective magnetization and the g-factor, which depend not only on the specific parameters of the samples, such as thickness of the ferromagnetic layer, but also on the deposition conditions. The results obtained were compared with known values in the literature and show the high sensitivity of the ferromagnetic resonance technique in the study of the magnetic anisotropy and the exchange bias phenomena. / A técnica de ressonância ferromagnética (FMR) foi utilizada para estudar propriedades magnéticas de bicamadas NiO/Co, NiO/Py e Py/FeMn (Py = Ni81Fe19) e tricamadas Co/NiO/Co, com diferentes espessuras das camadas ferromagnética e antiferromagnética, depositadas pela técnica de dc magnetron sputtering na presença de campo magnético de 400 Oe. Os experimentos de FMR foram todos realizados em temperatura ambiente usando um espectrômetro Bruker ESP- 300 de alta sensibilidade, com varredura do campo estático e técnicas padrões de modulação e detecção sensível à fase, em Banda-X (~ 9.70 GHz) e Banda-Q (~ 34.0 GHz). A dependência angular do campo de ressonância res H no plano do filme permitiu medir o campo de exchange bias observado em algumas bicamadas NiO/Py. Para as demais bicamadas e as tricamadas Co/NiO/Co foi possível medir a anisotropia uniaxial no plano da camada de Co. Os valores dos campos de exchange bias medidos para as bicamadas variaram de 29 Oe a 123 Oe, enquanto que os campos de anisotropia uniaxial variaram de 5 a 45 Oe. Para as tricamadas Co/NiO/Co, os campos de anisotropia uniaxial no plano apresentaram grande variação de 34 a 216 Oe. A dependência angular do campo de ressonância fora-do-plano do filme permitiu obter os valores da magnetização efetiva e do fator-g, dependentes não somente de parâmetros específicos das amostras, como a espessura da camada ferromagnética, mas também das condições de deposição. Os resultados obtidos foram comparados com valores conhecidos na literatura e mostram a alta sensibilidade da técnica de ressonância ferromagnética para o estudo da anisotropia magnética e do fenômeno de exchange bias

Made available in DSpace on 2014-07-29T15:12:48Z (GMT). No. of bitstreams: 1 Dissertacao - Joel Rocha da Silva.pdf: 557734 bytes, checksum: 97955f40a90305a3592aea224371f9ea (MD5) Previous issue date: 2008-05-27 / Magnetite nanoparticles were prepared by the coprecipitation of ions Fe2+ and Fe3+ using ammonia solution as precipitating agent. Maghemite nanoparticles were prepared by forced oxidation of magnetite nanoparticles in acidic medium using nitrate ions as oxidizing agent. The magnetic nanoparticles were used to the preparation of aqueous magnetic fluids samples by the functionalization of the nanoparticles with bilayers of laurate/laurate and laurate/Pluronic. Aliquots of the magnetic fluids were dried and the resultant powders were characterized by chemical analysis (the contents of ions Fe2+ and Fe3+), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The contents of ions Fe2+ and Fe3+ in all the samples showed that the nanoparticles are not pure magnetite or maghemite phases. X-ray powder diffraction (XRD) indicated the existence of inverse cubic spinel phase, but didn't permit the distinction between magnetite and maghemite phases. Based on the results of chemical and XRD analyses, the nanoparticles could be better characterized as reduced maghemite, which mean maghemite phase containing ions Fe2+. The average sizes of the oxide nanoparticles estimated by XRD were around of 10 nm. FTIR analyses showed that the nanoparticles were functionalized with bilayers of laurate/laurate and laurate/Pluronic. FTIR analyses also were indicative of the maghemite phase. The hydrodynamic size of the functionalized nanoparticles measured by PCS were in the range of 70-90 nm for the samples based on laurate and in the range of 100-200 nm for the samples containing Pluronic. The measurements of zeta potential showed that the magnetic fluids based on laurate bilayers presented better colloidal stability than that one based on bilayers of laurate/Pluronic. On the other hand, the studies of colloidal stability in cell culture medium by hydrodynamic size measurements showed the lost of colloidal stability of all the samples, in all the concentrations of medium investigated. The fluids with laurate/laurate bilayers showed higher ratio of aggregation in the culture medium than the fluids with laurate/Pluronic. The association of amphotericin B with nanoparticles was carried out only using the samples with laurate bilayers. The results showed that the ratio of association depends on the concentration of amphotericin added to the magnetic fluid. It was observed 100% of amphotericin association in the range of nanoparticles/amphotericin concentrations used, which in turn are adequated for posterior in vivo studies / Nanopartículas de magnetita foram preparadas pela coprecipitação dos íons Fe2+ e Fe3+ usando uma solução de amônia como o agente de precipitação. As nanopartículas de maguemita foram preparadas por oxidação forçada de nanopartículas de magnetita usando íons nitrato como o agente de oxidação, em meio ácido. As nanopartículas magnéticas foram usadas para a preparação de fluidos magnéticos aquosos pela funcionalização das nanopartículas com bicamadas de laurato/laurato e laurato/Pluronic. As alíquotas dos fluidos magnéticos foram secas e o pó resultante foi caracterizado por análise química (teores dos íons Fe2+ e Fe3+), difração de raios X pelo método do pó (DRX) e espectroscopia na região do infravermelho com transformada de Fourier (FT-IR). Os teores dos íons Fe2+ e Fe3+ em todas as amostras mostram que as nanopartículas não são fases puras da magnetita ou de maguemita. A difração de raios X (DRX) pelo método do pó indicou a existência da fase cúbica de espinélio inverso, mas não permite a distinção entre a magnetita e as fases de maguemita. Baseado nos resultados de análises químicas e de DRX, as nanopartículas poderiam ser melhor caracterizadas como maguemita reduzida, a qual resulta em uma fase de maguemita contento íons Fe2+. Os tamanhos médios das nanopartículas dos óxidos estimados por DRX foram em torno de 10 nm. As analises de FT-IR mostram que as nanopartículas foram funcionalizadas com bicamadas de laurato/laurato e laurato/Pluronic. As análises de FT-IR também foram indicativos da fase maguemita. O tamanho hidrodinâmico das nanopartículas funcionalizadas medidas por PCS foi em torno de 70-90 nm para amostras a base de laurato e em torno de 100-200 nm para amostras contendo Pluronic. As medidas de potencial zeta mostraram que os fluidos magnéticos a base de bicamada de laurato apresentam melhor estabilidade coloidal do que os a base de bicamada de laurato/Pluronic. Por outro lado, o estudo da estabilidade coloidal em meio de cultura por medidas de tamanho hidrodinâmico mostra a perda da estabilidade coloidal de todas as amostras, em todas as concentrações do meio investigado. Os fluidos com bicamadas de laurato/laurato mostraram taxas mais altas de agregação no meio de cultura do que os fluidos com laurato/Pluronic. Os estudos de associação de anfotericina B com nanopartículas foram realizados somente usando as amostras com bicamadas laurato/laurato. Os resultados mostraram que a taxa de associação depende da concentração de anfotericina adicionada ao fluido magnético. Foi observado 100% de associação da anfotericina na faixa da concentração nanopartículas/anfotericina usadas, que por sua vez são adequadas para posteriores estudos in vivo

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 &#955;, 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 &#955;, 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

The thesis entitled “Evolution of New Lipids and Molecular Gelators: Syntheses, Aggregation Properties and Applications” elucidates the design, synthesis, aggregation properties and application of new lipids based on α-tocopheryl backbone and also with triazacyclononane (TACN) moiety. This thesis also elucidates the synthesis and aggregation properties of molecular gelators based on pyrene-pentapeptide and naphthalene diimide (NDI) moiety. The work has been divided into five chapters. Chapter 1: Introduction: Self-assembled Molecular Aggregates and their Potential Applications This chapter describes the importance of different self-assemble mainly lipids and molecular gelator. Lipids mediated gene delivery, drug delivery and metal ion induced interaction are discussed. For liposomal gene delivery here we mainly describe example of cationic gemini lipids. This chapter also gives a comprehensive account of the research towards the development of novel liposomal drug delivery containing tocopheryl backbone. It also includes the utilization of liposome which could coordinate with metal ions and their interaction with different biological analyte. Here we also discuss a wide range of molecular gelator mainly based on NDI and amino acid or peptide. Chapter 2A: Physicochemical Characterization of Bilayer Membranes Derived from (±) α-Tocopherol Based Gemini Lipids and their Interaction with plasmid-DNA and Phosphatidylcholine Bilayers In this sub-chapter we discuss the membrane formation and aggregation properties of a series of (±) α-tocopherol based cationic gemini lipids (Figure 1) varying polymethylene spacer length (TnS; n = 3, 4, 5, 6, 8 and 12) are studied extensively while comparing with corresponding properties of monomeric counterpart (TM). Liposomal suspensions of all cationic lipids are characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and small angle x-ray diffraction studies. Aggregation properties of the gemini lipids are highly dependent on the spacer length and were significantly distinct from that of monomeric lipid (TM). Figure 1. Molecular structures of (±) α-tocopherol based cationic monomeric and six gemini lipids that differ in polymethylene spacer length. Stable monolayer formation at air water interface formation of each amphiphile is studied by Langmuir film balance technique. Interaction of liposome with plasmid DNA is studied by ethidium bromide (EB) intercalation assay. Micellar sodium dodecyl sulphate (SDS) mediated release of the plasmid DNA from various pre-formed lipoplex is also studied. Structural transformation of pDNA upon complexation with liposome is characterized by circular dichroism (CD) spectroscopy. Interaction of all tocopheryl lipids with a model phospholipid, L-α-dipalmitoyl phosphatidylcholine (DPPC) derived vesicles is thoroughly examined by differential scanning calorimetry (DSC) and DPH fluorescence anisotropy measurements. Succinctly, we perform a detailed physicochemical characterization on cationic monomeric and gemini lipids bearing tocopherol as their hydrophobic backbone. Chapter 2B: Physicochemical Characterization of Bilayer Membranes Derived from (±) α-Tocopherol Based Gemini Lipids Containing Hydroxyethyl Functionality in the Headgroups and their Interaction with plasmid-DNA and Phosphatidylcholine Bilayers This sub-chapter describes the synthesis and aggregation properties of series of tocopheryl-based monomeric and gemini cationic lipids with hydroxyethyl functionality (Figure 2) in the headgroup region. Gemini lipids of this given series differ in their polymethylene spacer -(CH2)n- chain lengths between cationic headgroups. All monomeric and gemini lipids are found to generate stable suspensions in aqueous media. Average hydrodynamic diameter and surface charge of liposome are characterized by DLS and zeta potential measurements. Atomic force microscopy and transmission electron microscopic studies show that all lipids form vesicular Figure 2. Molecular structures of (±) α-tocopherol based cationic monomeric and five new lipids with hydroxyethyl functionality in the headgroups that differ in polymethylene spacer length aggregates in aqueous media. XRD studies with the cast films of lipids reveal interdigitated bilayer arrangement of liposome. pDNA binding and release studies show that the interactions between gemini lipids and DNA depend upon the nature of head group as well as the length of the spacer between cationic head groups. Circular Dichroism (CD) spectra of lipoplex are measured to characterize structural transformation of pDNA upon complexation with liposome. DPH anisotropy and DSC studies of the DPPC-cationic lipid co-aggregates show that ~20 mol-% of of the tocopheryl gemini lipids is enough to abolish phase transition of DPPC membranes whereas more than 20 mol-% is required in case of their monomeric counterparts. Furthermore thermotropic properties of co-aggregates depend upon the length of the spacer of gemini lipid included in the mixture. Chapter 2C: Transfection Efficacies of α-Tocopherol Based Cationic Gemini Lipids with Hydroxyethyl Containing Headgroups. In this sub-chapter, we demonstrate transfection efficiency of five α-tocopheryl gemini lipid with hydroxyethyl containing headgroups (Figure 3). Co-liposomal formulations with helper lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) form highly stable formulations in water. Co-liposomal formulations with high molar ratio of DOPE (1.5:1 and 2:1) show higher transfection efficiency than liposome with low DOPE content liposome. Co-liposome of gemini lipids with longer spacer (n = 8 and 12) have higher level of luciferase expression in HepG2 cell line. In A549 and MCF-7 cell lines also co-liposomes of TH8S (2:1) are proved to be better than other co-liposome. N/P ratios of highest transfection are 1-1.5. These formulations are more potent than L2K in all three cancer cell line. The comparison with gemini lipid (T8T) without Figure 3. Molecular structures of (±) α-tocopherol based cationic gemini lipids that differ in polymethylene spacer length and helper lipid DOPE. hydroxylethyl group also proves the importance of hydroxyethyl functionalities. High serum stability of DOPE-gemini lipid formulation is attributed to tocopherol backbone and also hydroxyethyl functionalities. Circular dichroism data also show that lipoplex of DOPE-TH8S (2:1) have different conformation than the other. Relatively moderate binding efficiency and easy release of pDNA is also observed with DOPE-TH8S (2:1) in the EB-displacement assay which could be plausible reason for high transfection efficiency. Chapter 2D: Reduction Responsive Nanoliposomes of α-Tocopheryl-Lipoic Acid Conjugate for Efficacious Drug Delivery to Sensitive and Resistant Cancer Cells In this sub-chapter, we present lipid conjugates derived from biologically relevant molecules, i.e., tocopherol and lipoic acid (Figure 4). These conjugates (TL1 and TL2) are able to form stable nanoliposomes (~100 nm) that respond to the reducing environment of cells as shown by the treatments of 1,4-Dithiothreitol (DTT) and Glutathione (GSH). Figure 4. Molecular structures of tocopheryl-lipoic acid conjugates, TL1 and TL2 Nanoliposomes could efficiently load the drug (DOX) molecules and release them in response to the stimulus. Nanoliposomes are stable enough in the presence of serum and could deliver DOX inside drug sensitive and drug resistant cells in an efficient manner that is even better than the drug alone treatments as shown by means of flow cytometry and confocal microscopy analysis. DOX loaded nanoliposomal formulations show relatively less cell viability counts than those drug alone treatments. Chapter 3A: Interaction of Nickel (II) and mida ole it Triazacyclononane Modified Chelator Amphiphiles: A Potential Substrate for Immobilization of His-tag Protein on Hydrophilic Surface This sub-chapter describes two chelator amphiphiles based on 1, 4, 7-traiazaclonone (TACN) (Figure 5). These compounds could bind efficiently Ni2+ ion. Self-assemble of these amphiphiles form vesicular aggregates. Their packing properties of these amphiphiles are influence by Ni2+ and imidazole. Also influence of Ni2+ and imidazole in Langmuir monolayer isotherm of these amphiphiles at air-water interface are also studied. Figure 5. Molecular structures of TACNA chelator amphiphiles. These studies show the newly synthesized amphiphiles could immobilize histidine tagged protein on both bilayer and monolayer surface. One of these compounds with Ni2+ (C16TACNA-Ni2+) is used to transfer a His-tagged protein nucleolin on hydrophilicobic glass surface by Langmuir-Blodgett transfer technique. So, these compounds with Ni2+ could be very useful to attach different His-tagged protein or polypeptide of interest on the bilayer (liposome) or monolayer surface. Chapter 3B: Supramolecular Hosts for Enhancing the Selectivity of TACN Based Probes towards Copper (II): Differential Output Signals for Cysteine and Histidine In this sub-chapter, we have developed a new amphipathic probe compound 1 having TACN as the binding site and dansyl as signaling moiety (Figure 6). As TACN is known for its’ unspecific interaction with multiple ions, the probe shows response with most of the transition metal ions. However, incorporation into different supramolecular hosts (like micelle and vesicles) drastically improves the selectivity of compound 1 towards Cu2+ (diminution of bright green fluorescence) in water. Then we Figure 6. Molecular structures of dansylated TACN chelator amphiphiles. have also employed the Cu2+ complex of compound 1 for selective estimation of amino acids. Addition of cysteine regains the green emission of compound while histidine exhibits blue intense emission upon formation of ternary conjugate. Chapter 4: Transforming a β-Sheet Pyrenylated-VPGKG Sequence into pH Tolerent, Thixotropic Hydrogel by Arene-Perfluoroarene Interactions and Visualized Sensing of Calcium (II) Ion In this chapter we discuss self-assembly studies of a novel thermoresponsive, lipidated, pyrene-appended peptide, PyP (Figure 7). Size of the vesicular aggregates of the β-sheet forming peptide, PyP, strongly depends on the temperature of the solution in water. Further pyrene-octafluoronaphthalene (OFN) pair has been used as supramolecular synthon to induce hydrogelation of PyP in presence of equimolar amount of OFN via complementary quadrupole-quadrupole interactions. The gel shows excellent pH tolerant as well as thixotropic behavior. Detailed studies suggested the lamellar packing of the gelator in a right-handed helical fashion yielded vesicular aggregates. The sticky vesicles form gel via inter- Figure 7. Molecular structure of the Pyrenylated-VPGKG peptide (PyP) and octafluoronapthalene (OFN). Ca2+ ion reinforces the mechanical strength and also reduces the critical gelator concentration of the native gel through coordination with the free -COO- group of the gelator. Therefore, this present system could be used as a visualized sensor of Ca2+ ion. Chapter 5: First Report of Naphthalenediimide Based Metallo(organo)gel In this chapter, we have demonstrated synthesis of a novel asymmetric bolaamphiphilic (Figure 8). NDI derivative is capable of self assemble into stable gel in EtOH. Detailed studies reveal the gelator molecule of 1 adopt a parallel alignment in the lamellae during self-aggregation as nanoscopic spherical assemblies. In addition, dried gel of 1 shows nematic liquid crystalline phase. Further, we synthesize a novel metal-ligand discrete complex 2 in a nearly quantitative yield by reacting equimolar amount of 1 and PdCl2(PhCN)2. Figure 8. NDI derivative, 1, and its discrete metal complex 2. Complex 2 has been found to yield stable gel in dichloromethane (DCM) or chloroform (CHCl3) through the formation of high aspect ratio fibers. ROESY NMR experiment of Complex 2 has been found to yield stable gel in dichloromethane (DCM) or chloroform (CHCl3) through the formation of high aspect ratio fibers. ROESY NMR experiment of

The study of the co-existence of singlet superconductivity and ferromagnetism in bulk materials has been a long standing and intriguing problem in condensed matter physics since the superconductivity and ferromagnetism are quantum mechanically antagonistic to each other (i.e. parallel alignment of spins in the ferromagnet and Cooper pairs with oppositely aligned spins in the superconductor).Though it is incompatible to have the coexistence of singlet superconductivity and ferromagnetism in bulk compound, it is highly possible to artificially fabricate superconductor (S)/ferromagnet (F) heterostructures using various thin film deposition techniques and to study the interplay between the two antagonistic quantum phases over their characteristic length scales. The mutual interaction between the two competing order parameters at the interface in hybrid S/F heterostructures give rise to a variety of novel exotic physical phenomena. Moreover, the spin polarized transport and tunneling experiments in S/F heterostructures seem to be very much useful for providing important information on the spin dependent electronic properties of high Tc superconductors below and above the transition temperature. This can help a lot to understand the long debated unusual electronic properties and pairing mechanism of high Tc superconductors. In addition to the rich fundamental aspects buried in the study of S/F heterostructures, one can also use the spin dependent properties of high Tc superconductors in S/F heterostructures to design new spintronics devices from the application point of view. In this thesis an attempt is made to understand the spin polarized electron transport across S/F heterostructures where the superconductor used is YBa2Cu3O7-δand the ferromagnets are La0.5Sr0.5CoO3, La0.7Sr0.3MnO3, and La0.7Ca0.3MnO3. In addition, the magnetic properties of the La1-x SrxCoO3 system is also investigated in detail. The thesis is organized in six chapters and a brief summary of each chapter is given below. Chapter1 gives a brief introduction to the superconductivity, ferromagnetism and the interplay between superconductivity and ferromagnetism at the interface of S/F heterostructures. It also describes various exotic phenomena and the proximity effect that emerges at the S/F interface due to competing interactions. In addition, it also includes a discussion on various types of indirect magnetic interactions and basic idea about the spin glass ordering in magnetic materials. Chapter 2 outlines the basic principles of various experimental techniques employed for the work presented in this thesis. Chapter 3 describes an extensive magnetic and magnetotransport study of the La1-xSrxCoO3 system to understand the manifestation of various magnetic phases associated with it. The first section of this chapter aims at understanding the phase separation scenario in La0.85Sr0.15CoO3. Since the magnetic behavior of La0.85Sr0.15CoO3 is in the border area of spin glass (SG) and ferromagnetic (F) region in the x-T phase diagram; it has been subjected to a controversial debate for the last several years; while some groups show evidence for magnetic phase separation (PS), others show SG behavior. However, the experimental results presented in this thesis clearly demonstrate that the instability towards PS with inhomogeneous states or competing phases in La0.85Sr0.15CoO3 is not inherent or intrinsic to this compound; rather it is a consequence of the heat treatment condition during the preparation method. It is realized that low temperature annealed sample shows PS whereas the high temperature annealed sample shows the characteristics of canonical SG behavior. The second section of this chapter deals with a detailed study about the possible existence of various magnetic phases of La1-xSrxCoO3 in the range 0 ≤x ≤0.5. The dc magnetization study for x ≥0.18 exhibits the characteristic of ferromagnetic like behavior and for x<0.18, the SG behavior. More strikingly, the dc magnetization studies for x<0.18 rules out the existence of any ferromagnetic correlation that gives rise to irreversible line in the spin glass regime. The ac susceptibility study for x<0.18, exhibits a considerable frequency dependent peak shift, time-dependent memory effect, and the characteristic spin relaxation time scale τo ~10-13s, all pointing towards the characteristics of SG behavior. On the other hand, the ac susceptibility study in the higher doping ferromagnetic side exhibits the coexistence of glassy and ferromagnetic behavior. The glassiness is interpreted in terms of inter-cluster interaction. The reciprocal susceptibility vs. T plot in the paramagnetic side adheres strictly to Curie-Weis behavior and does not provide any signature for the pre-formation of ferromagnetic clusters well above the Curie temperature. The magnetotransport study reveals a cross over from metallic behavior to semiconducting like behavior for x ≤0.18 and the system exhibits a peak in MR in the vicinity of Tc on the metallic side and a large value of MR at low temperature on the semiconducting side. Such high value of MR in the semiconducting spin glass regime is strongly believed due to spin dependent part of random potential distribution. Based on the present experimental findings, a revised phase diagram has been constructed and each phase has been characterized with its associated properties. Chapter 4 deals with a comprehensive study of thickness dependent structural, magnetic and magnetotransport properties of oriented La0.5Sr0.5CoO3 thin films grown on LaAlO3 by pulsed laser deposition. The films are found to undergo a reduction in Curie temperature with decrease in film thicknesses and it is primarily caused by the finite size effect since the finite scaling law holds good over the studied thickness range. The contribution from strain induced suppression of the Curie temperature with decreasing film thickness is ruled out since all the films exhibit a constant out of plane tensile strain (0.5%) irrespective of their thickness. The coercivity of the films is observed to be an order of magnitude higher than that of the bulk. This is attributed to the local variation of the internal strain that introduces strong pinning sites (via. magnetoelastic interaction) for the magnetization reversal. In addition, an increase in the electrical resistivity and coercivity is observed with decrease in film thickness and it is strongly believed to be due to the interface effect. Chapter5 reports on the investigation of the effect of ferromagnetic layer on (i) pair breaking effect and (ii) vortex dynamics in different superconducting(S)/ ferromagnetic (F) bi-layers grown by pulsed laser deposition. The current (I) dependent electrical transport studies in the S/F bi-layers exhibit a significant reduction in the superconducting transition temperature with the increase in applied current as compared to single YBa2Cu3O7-δlayer and it follows I2/3 dependence in accordance with the pair breaking effect. Moreover, the superconducting transition temperature in YBa2Cu3O7-δ/ La0.7Sr0.3MnO3 bilayer is surprisingly found to be much larger than the YBa2Cu3O7-δ/La0.5Sr0.5CoO3. It appears that the current driven from a material with low spin polarization (-11%) like La0.5Sr0.5CoO3 can also suppress the superconductivity to a larger extent. This indicates that the degree of spin polarization of the ferromagnetic electrode is not the only criteria to determine the suppression of superconductivity by pair breaking effect in superconductor/ferromagnet hybrid structures; rather the transparency of the interface for the spin polarization, the formation of vortex state due to the stray field of ferromagnetic layer and the ferromagnetic domain patterns might play significant roles to determine such effect. More interestingly, the spin diffusion length in YBa2Cu3O7-δis found have a much longer length scale than that reported earlier in the study of F/ S heterostructures. The activation energy (U) for the vortex motion in S/F bilayers is reduced remarkably by the presence of the F layers. In addition, the U exhibits a logarithmic dependence on the applied magnetic field in the S/F bilayers suggesting the existence of decoupled 2D pancake vortices. This result is discussed in terms of the reduction in the effective S layer thickness and the weakening of the S coherence length due to the presence of F layers. Chapter 6 deals with the magnetotransport study on two different kind of F/S/F trilayers viz. La0.7Sr0.3MnO3/YBa2Cu3O7-δ/La0.7Sr0.3MnO3 and La0.5Sr0.5CoO3/YBa2Cu3O7-δ/La0.7Ca0.3MnO3 with changes in superconducting and ferromagnetic layer thickness. The activation energy for the vortex motion in F/S/F trilayer is found to decrease considerably as compared to S/F bilayer and it also exhibits a logarithmic dependence on magnetic field which gives the signature of existence of decoupled 2D pancake vortices. The magnetotransport study reveals that a much lower magnetic field is required to suppress the superconductivity in trilayer as compared to single YBCO layer. Moreover, the transport study also reveals that a threshold thickness of YBCO is required for the onset of superconductivity in trilayer structure and the onset of superconducting Tc increases with increase in YBCO thickness. More strikingly, a remarkable unconventional anisotropic superconducting Tc (Tc H║c-axis<Tc H⊥c-axis) is observed in La0.5Sr0.5CoO3/YBa2Cu3O7-δ/La0.7Ca0.3MnO3 trilayer for the magnetic field applied parallel and perpendicular to c-axis. The trilayer system also exhibits a huge positive magnetoresistance (MR) below superconducting Tc and it could arise due to vortex dissipation in liquid state of superconductor in the tri-layer structure. Finally, the thesis concludes with a general conclusion and an outlook in this area of research.

Tumour necrosis factor-stimulated gene-6 (TSG-6) is a protein expressed in a wide range of cell types and tissues, predominantly in response to inflammatory stimuli. The expression of TSG-6 is believed to be associated with the protection of tissues from the damaging effects of inflammation. In animal models treatment with TSG-6 protein has been found to reduce inflammatory damage in myocardial infarction, corneal injury and arthritis. Endogenous TSG-6 production has been suggested to play a protective role in inflammatory arthritis and has been implicated in bone homeostasis. The expression of TSG-6 is also essential in the process of cumulus matrix formation that occurs around the oocyte in the periovulatory period and is necessary for successful ovulation and fertilisation. In many cases the mechanism underlying a particular TSG-6 function is not fully understood. TSG-6 has numerous binding partners including the serum glycoprotein inter-alpha-inhibitor (IαI), the growth factor bone morphogenetic protein-2 (BMP-2) and the extracellular matrix protein fibronectin, as well as glycosaminoglycans (GAGs) such as hyaluronan and heparan sulphate (HS). The TSG-6 protein is mostly composed of contiguous Link and CUB domains, with the majority of ligand binding sites identified within the Link module. The CUB domain of TSG-6 has been less extensively studied. Here biophysical techniques have been used to investigate the TSG-6 interactome including both the Link module and CUB domain. Intrinsic fluorescence spectroscopy was used to establish the metal-ion binding properties of the CUB domain, which was established to have a high affinity Ca2+-binding site. Using surface plasmon resonance (SPR), a novel metal-ion dependent interaction was found for the CUB domain of TSG-6 and the heavy chains (HCs) of IαI. Investigation using mutants of both the CUB domain of TSG-6 and HC of IαI established that the metal-ion binding sites within each protein are involved in the interaction. SPR analysis was also used to define the affinities and binding sites for TSG-6 interactions with fibronectin and BMP-2. High affinity interactions between TSG-6 ligands were also revealed (e.g. BMP-2 and HC, fibronectin and HC) and their binding sites defined. The discovery of the novel interactions between these TSG-6 ligands suggests crosstalk within the TSG-6 interactome, with the potential for ternary complex formation or indeed hierarchical orders of binding. Thus work was undertaken to develop a passivated lipid bilayer platform for use with surface sensitive techniques. This platform was used to investigate the hierarchy of protein and GAG interactions using quartz crystal microbalance with dissipation monitoring (QCM-D) and dual polarisation interferometry (DPI). The investigation revealed a novel role for the Link module of TSG-6 in heparin condensation, potentially via protein dimerisation and/or oligomerisation which could affect heparin/HS functions within the extracellular matrix (ECM). Thus the biophysical analysis of TSG-6 presented here has identified novel interactions and functions of TSG-6 which may provide mechanisms for the protective functioning of TSG-6 in inflammation and its ECM structuring role in ovulation.