Made available in DSpace on 2014-10-09T12:26:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:12Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Chapter 1: Introduction to the luminescent properties of lanthanides Luminescence properties of trivalent lanthanides have been explored extensively over the past few decades owing to their unique properties. Lanthanides emission is known to be due to intra-configurational f-f transitions. Because the partially filled 4f shell is well shielded from its 26 environment by the closed 5sand 5pshells, the ligands in the first and second coordination sphere perturb the electronic configurations of the trivalent lanthanide ions only to a very limited extent. This leads to interesting properties such as long lifetimes, sharp line-like emissions etc. which in turn make lanthanides very attractive choice for commercial optical applications. Despite this, the scope of applications remained limited because of the low molar extinction coefficient values of the forbidden lanthanide f-f transitions. However, this problem has been successfully addressed by complexing the lanthanide ion with suitable ligands which can sensitize it resulting in a significant increase in the emission intensity (so called “antenna effect”). The strategy worked very well and resulted in widespread applications of lanthanides form biology to optoelectronics. This chapter discusses elementary ideas regarding the mechanism of sensitization and relevant examples that traces various applications of such lanthanide complexes from the current literature. Chapter 2: A self-assembled Europium Cholate hydrogel: a novel approach towards lanthanide sensitization Luminescent lanthanides can be of great value in a number of possible applications but their scope is limited by their intrinsic low molar absorptivities. Though this problem can be circumvented by complexing the lanthanide ion with suitable chelating ligands to improve the luminescence properties drastically, the design of such systems often involves meticulous planning and laborious synthetic steps to obtain a ligand suitable for the job. It is therefore desirable to have a simpler version of a sensitizing system that does not require the complexities of a chelating ligand but can sensitize trivalent lanthanides with comparable efficiency. It was observed in our group that divalent metal ions (Ni2+, Zn2+, Cu2+, Coetc.) form hydrogels on addition of sodium cholate. We extended to obtain hydrogels of trivalent lanthanides. Furthermore, when the gel was doped with pyrene, a ten-fold increase in the intensity of Eu(III) emission was observed (Fig 2). Thus we established a unique way to sensitize lanthanides in a hydrogel media by non-coordinating chromophores. The approach was completely modular in nature and avoids any laborious synthesis. We also tried other derivatives of pyrene as sensitizers and found that 1-pyreneboronic acid also caused similar sensitization of Eu(III). Fig 2. (a) Schematic representation of the sensitization process (the arrangement of molecules in the gel fiber is arbitrary). Eu-cholate (5 mM/15 mM) gel (a) normal light and (b) 354 nm UV excitation in the presence of 6 μM pyrene Further studies revealed, that 2,3-dihydroxynapthalene (DHN) can sensitize Tb(III) in a similar hydrogel. We also demonstrated Tb(III) to Eu(III) energy transfer process occurring in the gel when doped with DHN. This allowed us to achieve a hydrogel system with tunable luminescence properties (by varying relative ratios of Tb(III) and Eu(III) ). When the effect of divalent metal ions on such energy transfer processes were explored, it was observed that the luminescence from the composite gel of Tb(III)/ Eu(III) is tunable by Zn(II) and through proper manipulation of concentrations one can obtain white light emitting gel (Fig 3). Fig 3. Effect of Zn(II) (from left to right 0 mM, 2.8 mM, 11.3 mM) on Tb3+ (4.5 mM)/Eu3+ (0.11mM)/ sodium cholate (13.6 mM) gels. b) Tb/Eu/Zn-cholate gel (Tb3+ (4.4 mM), Eu3+ (0.11 mM), Zn2+ (7.4 mM), NaC (13.6 mM, DHN 0.2 mM) under 365 nm UV lamp (c) CIE 1931 diagram depicting the luminescence as white (black spot). Chapter 3. A “Pro-Sensitizer” based Sensing of Enzymes using Tb(III) Luminescence in a Hydrogel matrix This chapter descirbes design and realisation of a sensor system based on Tb(III) luminescnece for the detection of enzymes. The idea involved synthesizing a covalently modified DHN molecule by attaching appropriate enzyme cleavable units. We coined the term “pro-sensitizer”to describe the modified molecule which would not sensitize Tb(III) in the gel matrix but when proper enzymes are applied the free form of DHN would be released triggering a luminescence response from Tb(III). This would enable us to monitor the acitivities of the particular enzyme by examining the luminescence intensity enhancement with time (Fig 4) Fig 4. A “pro-sensitizer” based approach to detect different types of enzymes in a hydrogel matrix through Tb(III) luminescence. We applied the idea to develop a novel luminogenic gel probe for inexpensive and rapid detection of three different hydrolases, lipase, β–glucosidase and α-chymotrypsin. The corresponding “pro-sensitizer”for each enzyme were synthesized (Fig 5).The sensing technique depends on the gel matrix to provide the nessesary platform for lanthanide sensitization. Thereofore, it enjoys an edge over the contemporary techniques that typically involve specially designed and synthesized multidentate chelating ligands for this purpose. We also determined important kinetic parameters of all the enzymes, thus enabling us to have a better insight into the activity of the enzymes in the hydrogel matrix. Fig 4. Pro-sensitizers molecules for (1) lipase, (2) β-glucosidase and (3)α-chymotrypsin Chapter 4. A novel approach towards templated synthesis of lanthanide trifluoride nanoparticles Nanomaterials with excellent optical properties have been of special interest. Lanthanide derived nanoparticles, owing to their unique physical properties, provide an excellent choice for applications such as biolabels, lasers, optical amplifiers, and optical-display phosphors. Several types of lanthanide nanoparticles or nanocrystals are reported in the literature such as Nd2O3, Eu2O3, Gd2O3, Tb2O3, and Y2O3. Among them lanthanide fluoride nanoparticles have emerged as the best choice because of their low phonon energy, and thus minimum quenching of emissive Lnions thereby allowing maximum efficiency for several optical applications. In previous literature precedence, LnF3 nanoparticles were typically synthesized following conventional approaches which necessitate use of high temperatures, high pressures (hydrothermal techniques) and capping ligands. In this chapter, we demonstrated a simpler synthesis of LnF3 nanoparticles at ambient temperatures without the requirement of added capping agents. The room temperature synthesis of LnF3 was unprecedented and was achieved simply by diffusing NaF solution through the hydrogels of corresponding Ln-cholate gels. The nanoparticles were characterized by transmission electron microscopy (TEM) and by powder XRD analysis which established the presence of very small (3-4 nm) nanoparticles mono-dispersed uniformly over the the gel matrix (Fig 6). The LnF3 containing xerogels of Tb(III) and Eu(III) cholate gels were also shown to be highly emissive. Fig 6. HRTEM images of a) TbF3, b) GdF3, c) NdF3 and d) DyF3 in their corresponding gel media.

Made available in DSpace on 2014-10-09T12:55:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:56Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:06/53634-3

Este trabalho teve como principal objetivo produzir membranas porosas de carboximetilquitosana e hidrogéis de quitosana com propriedades físico-químicas e mecânicas adequadas para aplicações em Engenharia de Tecidos. Para isso, quitosanas com diferentes graus de acetilação (4,0%<GA<40%) e de elevada massa molar média viscosimétrica (Mv>750.000 g.mol-1) foram produzidas através da aplicação de processos consecutivos de desacetilação assistida por irradiação de ultrassom de alta intensidade (DAIUS) à beta-quitina extraída de gládios de lulas Doryteuthis spp. A carboximetilação de quitosana extensivamente desacetilada (Qs-3; GA=4%) foi realizada pela reação com ácido monocloroacético em meio isopropanol/solução aquosa de NaOH, gerando a amostra CMQs-0 (GS≈0,98; Mv≈190.000 g.mol-1). A irradiação de ultrassom de alta intensidade foi empregada para tratar solução aquosa de CMQs-0 durante 1 h e 3 h, resultando nas amostras CMQs-1 (Mv≈94.000 g.mol-1) e CMQs-3 (Mv≈43.000 g.mol-1), respectivamente. Para a produção de membranas reticuladas, genipina foi adicionada em diferentes concentrações (1,0x10-4 mol.L-1, 3,0x10-4 mol.L-1 ou 5,0x10-4 mol.L-1) às soluções aquosas das CMQs, que foram vertidas em placas de Petri e a reação de reticulação procedeu por 24 h. Em seguida, as membranas reticuladas (M-CMQs) foram liofilizadas, neutralizadas, lavadas e liofilizadas novamente, resultando em nove amostras, que foram caracterizadas quanto ao grau médio de reticulação (GR), grau médio de hidratação (GH), morfologia, propriedades mecânicas e quanto à susceptibilidade à degradação por lisozima. O grau médio de reticulação (GR) foi tanto maior quanto maior a concentração de genipina empregada na reação, variando de GR≈3,3% (M-CMQs-01) a GR≈17,8% (M-CMQs-35). As análises de MEV revelaram que as membranas reticuladas M-CMQs são estruturas porosas que apresentam maior densidade de poros aparentes quanto maiores os valores de Mve GR. Entretanto, as membranas preparadas a partir de CMQs de elevada massa molar (Mv>94.000 g.mol-1) e pouco reticuladas (GR<10%), apresentaram propriedades mecânicas superiores em termos de resistência máxima à tração (>170 kPa) e elongação máxima à ruptura (>40%). Por outro lado, as membranas mais susceptíveis à degradação enzimática foram aquelas preparadas a partir de CMQs de baixa massa molar (Mv≈43.000 g.mol-1) e que exibiram baixos graus de reticulação (GR<11%). Hidrogéis estáveis de quitosana sem o uso de qualquer agente de reticulação externo foram produzidos a partir da gelificação de soluções aquosas de quitosana com solução de NaOH ou vapor de NH3. Os hidrogéis produzidos a partir de soluções de quitosana de elevada massa molar média ponderal (Mw≈640.000 g.mol-1) e extensivamente desacetilada (DA≈2,8%) em concentrações poliméricas acima 2,0%, exibiram melhores propriedades mecânicas com o aumento da concentração polimérica, devido à formação de numerosos emaranhamentos físicos das cadeias poliméricas em solução. Os resultados mostram que as propriedades físico-químicas e mecânicas dos hidrogéis de quitosana podem ser controladas variando a concentração do polímero e o processo de gelificação. A avaliação biológica de tais hidrogéis para a regeneração de miocárdio infartado de ratos revelou que os hidrogéis de quitosana preparados a partir de soluções de polímero a 1,5% foram perfeitamente incorporados sobre a superfície do epicárdio do coração e apresentaram degradação parcial acompanhada por infiltração de células mononucleares. / The aim of this study was to produce and characterize porous membranes of carboxymethylchitosan and chitosan-based hydrogel with physicochemical and mechanical properties appropriate for applications in tissue engineering. For this, chitosans with different degrees of acetylation (4,0%<GA<40%) and high viscosity average molecular weight (Mv>750.000 g.mol-1) were produced by application of consecutive processes of ultrasound-assisted deacetylation (USAD) of the beta-chitin extracted from squid pens (Doryteuthis spp.). The carboxymethylation of extensively deacetylated chitosan (Qs-3; DA=4%) was carried out by reaction with monochloroacetic acid in isopropanol/aqueous NaOH, producing CMQs-0 sample (GS≈0,98; Mv≈190.000 g.mol-1). The ultrasonic irradiation was employed to depolymerize the CMQs-0 samples by irradiation for 1 h and 3 h, resulting in CMQs-1 samples (Mv≈94.000 g.mol-1) and CMQs-3 (Mv≈43.000 g.mol-1), respectively. For the production of crosslinked membranes, genipin was added at different concentrations (1,0x10-4 mol.L-1, 3,0x10-4 mol.L-1 ou 5,0x10-4 mol.L-1) in the aqueous solutions of CMQs, which were poured into Petri dishes and the crosslinking reaction proceeded for 24 h. Then, the crosslinked membranes (M-CMQs) were lyophilized, neutralized, washed, and lyophilized again resulting in nine samples which were characterized by crosslinking degree (CrD), swelling ration (SR), morphology, mechanical properties and the susceptibility to enzymatic degradation by lysozyme. The crosslinking degree (CrD) increased with increasing concentration of genipin used in the reaction, varying from CrD≈3.3% (M-CMQs-01) to CrD≈17.8% (M-CMQs-35). The SEM analysis showed that the crosslinked membranes M-CMQs are porous structures that have a higher apparent pores density with increasing values of Mv and CrD. However, the membranes prepared from high molecular weight CMQs (Mv>94.000 g.mol-1) and low crosslinked (GR<10%) showed superior mechanical properties in terms of ultimate tensile strength (>170 kPa) and maximum elongation at break (>40%). However, the more susceptible membrane to enzymatic degradation was prepared from low molecular weight CMQs (Mv≈43.000 g.mol-1) and low cross-linking degrees (GR<11%). Stable chitosan hydrogels without any external crosslinking agent was successfully achieved by inducing the gelation of a viscous chitosan solution with aqueous NaOH or gaseous NH3. The hydrogels produced from high molecular weight (Mw≈640.000 g.mol-1) and extensively deacetylated chitosan (DA≈2,8%) at polymer concentrations above ≈2.0% exhibited improved mechanical properties due to the increase of the chain entanglements and intermolecular junctions. The results also show that the physicochemical and mechanical properties of chitosan hydrogels can be controlled by varying their polymer concentration and by controlling the gelation kinetics, i.e. by using different gelation routes. The biological evaluation of such hydrogels for regeneration of infarcted myocardium revealed that chitosan hydrogels prepared from 1.5% polymer solutions was perfectly incorporated onto the epicardial surface of the heart and presented partial degradation accompanied by mononuclear cell infiltration.

A fibroína de seda é uma proteína sintetizada pela espécie Bombyx mori, popularmente conhecida como bicho-da-seda. O casulo de Bombyx mori é composto por fibras de fibroína e pela sericina, responsável por unir os fios de fibroína. A fibroína é um polímero natural bastante versátil e pode ser processada de maneira a formar materiais como filmes, microesferas e hidrogéis. Os hidrogéis são redes tridimensionais formadas por macromoléculas e capazes de absorver grande quantidade de água sem perder sua integridade estrutural. Devido à características como biocompatibilidade, elevado teor de água e boas propriedades de difusão de oxigênio e nutrientes, os hidrogéis são amplamente utilizados em pesquisa biomédica. A fibroína é biodegradável, termicamente estável, altamente cristalina, flexível, resistente à tração, além de insolúvel em água e na maioria dos solventes orgânicos. A fibroína derivada das sedas Frison Extra e Meada 21 Denier foi separada da sericina pelo processo de degomagem, onde as fibras de seda foram imersas em soluções alcalinas e submetidas à aquecimento com posterior remoção de sericina. Os fios de fibroína foram dispersos nas soluções de CaCl2:H2O, LiCl:H2O e LiCl:EtOH:H2O. Diferenças nos tempos de dispersão para amostras distintas degomadas ou não foram observadas, bem como para cada um dos sistemas salino/solvente empregados. Após o processo de dispersão da fibroína as dispersões obtidas foram caracterizadas quanto à textura e reologia. As amostras não degomadas apresentaram maior firmeza e aumento do módulo elástico G\'. Algumas amostras contendo sericina ou etanol apresentaram comportamento newtoniano. Em uma segunda etapa, as amostras foram dialisadas para a produção do hidrogel e em seguida liofilizadas. Não houveram diferenças entre os tempos de gelificação para amostras distintas. Finalmente objetivou-se a caracterização dos hidrogéis obtidos por meio de ensaios termogravimétricos, difratométricos, espectrofotométricos e microscópicos. Todos os hidrogéis de fibroína de seda apresentaram alta resistência térmica, com presença predominante da conformação em folha-β da fibroína. Morfologicamente, os hidrogéis obtidos a partir de dispersões em LiCl:EtOH:H2O e CaCl2:EtOH:H2O apresentaram aspecto de rede enovelada, enquanto que os hidrogéis oriundos de dispersões em LiCl:H2O apresentaram estrutura lamelar. / The silk fibroin is a protein synthesized by Bombyx mori species, popularly known as silkworm silk. The Bombyx mori cocoon is composed of fibroin fibers and the sericin protein, which is responsible for joining the fibroin yarns. The fibroin is a quite versatile natural polymer and can be processed to form materials such as films, microspheres and hydrogels. Hydrogels are three-dimensional networks formed by macromolecules and capable of absorbing large quantities of water without losing their structural integrity. Due to biocompatibility, ability to mimic biological tissues, high water content and good diffusion properties of oxygen and nutrients, hydrogels are widely used in biomedical research. The fibroin is biodegradable, thermally stable, highly crystalline, flexible and tensile resistant. Besides, it is insoluble in water and in most organic solvents. The fibroin from Frison Extra and Meada 21 Denier silks was separated from the sericin by the degumming process, whereby the silk fibers were immersed in alkaline solutions and subjected to heating with subsequent dissolution and removal of sericin. Fibroin yarns were dispersed in various solutions: CaCl2:H2O; LiCl:H2O; and LiCl:EtOH:H2O. It was observed that according to the fibroin type and solvent solution used the time to achieve dispersion varied. Texture and rheology were determined for every sample after dispersion. All non-degummed samples had shown increased firmness and elastic module G\'. It was observed that the samples presented a wide behavior range, some that contained sericin or ethanol presented Newtonian behavior. Subsequently the samples were dialyzed to obtain the hydrogels and lyophilized. All samples (with exception of two) have formed hydrogels in a 24 hours period. The lyophilized hydrogels were analyzed by thermogravimetry, diffractometry, spectrophotometry and microscopy. All silk fibroin hydrogels presented high thermic resistance with β-sheet predominance. Morphologically, all hydrogels obtained from LiCl:EtOH:H2O and CaCl2:EtOH:H2O solutions had shown entangled aspect wile hydrogels from LiCl:H2O solutions had shown lamellar structures.

Due to an increased environmental awareness and thus, concerns over the use of fossil-based monomer for polymer production, there is an ongoing effort to find alternatives to non-renewable traditional monomers. This has ushered in the rapid growth in the development of bio-based materials such as green monomers and biodegradable polymers from vegetable and animal resources. Glycerol, as a renewable bio-based monomer, is an interesting candidate for sustainable polymer production. Glycerol is a renewable material that is a by-product of the transesterification of vegetable oils to biodiesel. Utilization of the excess glycerol derived from the growing biodiesel industry is important to oleochemical industries. The main objective of this thesis was to produce high molecular weight polyglycerol from glycerol and synthesize stimuli-responsive polyglycerol hydrogels. The work began with an investigation of the step-growth polymerization of glycerol to relatively high molecular weight polyglycerol using several catalysts. The catalytic reaction mechanisms were compared and the polymer products were fully analyzed. High molecular weight partially branched polyglycerol with multimodal molecular weight distributions was obtained. The polymerization of glycerol proceeded fastest with sulphuric acid as catalyst as indicated by the highest observed conversion of monomer along with the highest molecular weights. Theoretical models were used to predict the gel point and to calculate monomer functionality. High molecular weight polyglycerol was used to synthesize novel stimuli-responsive hydrogels. Real-time monitoring of step-growth polymerization of glycerol was investigated using in-line and off-line Attenuated Total Reflectance/Fourier Transform infrared (ATR-FTIR) technique.

The objective of this research was to study the adsorption and photodegradation of Malachite Green (MG) dye by using poly(2-hydroxyethylmethacrylate) (PHEMA) hydrogel and nanocomposite TiO2PHEMA hydrogel. The nanocomposite gels were characterized by FT-IR and XRD. The adsorption of MG dye was examined through monitoring UV-Vis absorption. The kinetic study indicated that the adsorption follows the first order kinetics. The adsorption equilibrium data fit well to the Langmuir isotherm model. The photodegradation of MG dye was examined using TLC UV lamp and medium pressure Hg lamp. It was determined that the unloaded composite gels adsorb MG dye from the solution at the beginning while under the photochemical condition. The dye in the gel was eventually photodegraded, indicating that the photodegradation process is still effective to dyes in the gel system. The composite gels containing anatase/rutile mixed phase titania are much better photocatalysts than those containing pure phase titania (either rutile or anatse).

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22497号 / 農博第2401号 / 新制||農||1077(附属図書館) / 学位論文||R2||N5277(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 矢野 浩之, 教授 和田 昌久, 教授 辻井 敬亘 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

This diploma thesis is focused on development and characterization of synthetic hydrogel materials containing humic acids. Based on the literature review, procedure for the preparation of synthetic superabsorbent containing humic acids was designed and optimized in order to maintain required functionality of the resulting materials, such as swelling abilities and to the controlled the release of humic substances. Very important part of this work was also characterization of superabsorbents by wide range of routine physic-chemical methods (rheometry, moisture analyzers, FT-IR). Preparation of these materials is aimed to their use in agriculture and in the environment.

This diploma thesis deals with application of microencapsulation techniques in development of hydrogel controlled-release systems in which the main role is played by humic acids, biopolymer chitosan, compound fertilizer NPK and 3-indoleacetic acid. This paper continues my bachelor thesis topic about utilization of polyelectrolyte complexes. The aim of this work was to develop a literature review focusing on the microencapsulation techniques and according to its results optimize the method. Microencapsulation was performed with a commercial encapsulator BUSCHI B-395 Pro and a release of individual components into a water was measured. An amout of released substances was measured by UV-VIS method and HPLC analysis. Practical part also included testing of repeated swelling and drying. It was found that suitable composition and combination of ingredients form hydrogels for further use in agriculture.