Tez (Doktora) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Kimya Anabilim Dalı, 2008. / Bibliyografya var.

O processamento de peles para a fabricação de couro utiliza uma mistura complexa de substâncias - dentre elas, os taninos - que torna o tratamento de águas residuais difícil e oneroso. Vários estudos estão sendo conduzidos na tentativa de melhorar o tratamento e até mesmo reutilizar o efluente tratado. Neste trabalho foi avaliado o desenvolvimento de adsorventes funcionais sintetizados pelo método solgel e dotados de impressão molecular, para adsorção de compostos de taninos. Por serem de fácil preparação, os materiais híbridos obtidos viabilizam a sua produção para o uso como sólidos adsorventes. A caracterização dos materiais híbridos orgânico-inorgânico obtidos foi realizada por análise de Porosimetria de nitrogênio (BET), Espalhamento de raios-X a baixo ângulo (SAXS), Espectroscopia de refletância difusa no UV-vis (DRS), Espectroscopia de infravermelho com transformada de Fourier (FT-IR) e Potencial Zeta (PZ). As características estruturais e texturais dos materiais híbridos gerados variaram para cada rota sol-gel e processo de extração de template empregado, resultando em materiais com diferentes capacidades de adsorção. As sílicas sem funcionalização não foram capazes de adsorver os compostos de tanino em solução aquosa, enquanto que as sílicas funcionalizadas com APTES demonstraram sua potencialidade como adsorvente para os compostos testados, atingindo remoções superiores a 80%. Diferenças nas capacidades de adsorção entre as sílicas funcionalizadas com e sem impressão molecular também foram observadas, onde a sílica sem impressão apresentou uma adsorção superior de taninos, indicando que mais estudos são necessários para encontrar um processo de extração eficiente do template. É importante salientar que as sílicas que obtiveram a maior capacidade de adsorção, puderam adsorver os compostos de taninos por vários ciclos consecutivos. / The processing of hides for leather manufacturing uses a complex mix of chemicals that makes the wastewater treatment difficult and costly. Several studies are being conducted in attempt to improve the treatment and even reuse the treated effluent. This study evaluated the development of functional adsorbent synthesized by the molecular imprinting method in a sol-gel matrix, for adsorbing tannin compounds. Easy to prepare, hybrid materials obtained enable their production for use as solid adsorbents. The characterization of organic-inorganic hybrid materials obtained was performed by nitrogen porosimetry analysis (BET), small-angle X-ray scattering (SAXS), diffuse reflectance spectroscopy (DRS), Fourier-Transform Infrared Spectroscopy (FT-IR) and Zeta Potential (PZ). The structural and textural characteristics of hybrid materials ranged for each sol-gel route and template employed extraction process resulting in materials with different adsorption capacities. The silicas without functionalization were unable to adsorb the tannin compounds in aqueous solution, whereas the silica functionalized with APTES demonstrated the potential of the adsorbent for the tested compounds, with removals above of 80%. Differences in adsorption capacities between functionalized silica with and without molecular imprinting were observed where the unprinted silica had a higher adsorption of tannins, indicating that more studies are needed to find a process of efficient template extraction to improve adsorption capacity to the imprinted materials. Further, the silicas with improved adsorption capacity could adsorb the tannin compounds for several consecutive cycles of adsorption.

O processamento de peles para a fabricação de couro utiliza uma mistura complexa de substâncias - dentre elas, os taninos - que torna o tratamento de águas residuais difícil e oneroso. Vários estudos estão sendo conduzidos na tentativa de melhorar o tratamento e até mesmo reutilizar o efluente tratado. Neste trabalho foi avaliado o desenvolvimento de adsorventes funcionais sintetizados pelo método solgel e dotados de impressão molecular, para adsorção de compostos de taninos. Por serem de fácil preparação, os materiais híbridos obtidos viabilizam a sua produção para o uso como sólidos adsorventes. A caracterização dos materiais híbridos orgânico-inorgânico obtidos foi realizada por análise de Porosimetria de nitrogênio (BET), Espalhamento de raios-X a baixo ângulo (SAXS), Espectroscopia de refletância difusa no UV-vis (DRS), Espectroscopia de infravermelho com transformada de Fourier (FT-IR) e Potencial Zeta (PZ). As características estruturais e texturais dos materiais híbridos gerados variaram para cada rota sol-gel e processo de extração de template empregado, resultando em materiais com diferentes capacidades de adsorção. As sílicas sem funcionalização não foram capazes de adsorver os compostos de tanino em solução aquosa, enquanto que as sílicas funcionalizadas com APTES demonstraram sua potencialidade como adsorvente para os compostos testados, atingindo remoções superiores a 80%. Diferenças nas capacidades de adsorção entre as sílicas funcionalizadas com e sem impressão molecular também foram observadas, onde a sílica sem impressão apresentou uma adsorção superior de taninos, indicando que mais estudos são necessários para encontrar um processo de extração eficiente do template. É importante salientar que as sílicas que obtiveram a maior capacidade de adsorção, puderam adsorver os compostos de taninos por vários ciclos consecutivos. / The processing of hides for leather manufacturing uses a complex mix of chemicals that makes the wastewater treatment difficult and costly. Several studies are being conducted in attempt to improve the treatment and even reuse the treated effluent. This study evaluated the development of functional adsorbent synthesized by the molecular imprinting method in a sol-gel matrix, for adsorbing tannin compounds. Easy to prepare, hybrid materials obtained enable their production for use as solid adsorbents. The characterization of organic-inorganic hybrid materials obtained was performed by nitrogen porosimetry analysis (BET), small-angle X-ray scattering (SAXS), diffuse reflectance spectroscopy (DRS), Fourier-Transform Infrared Spectroscopy (FT-IR) and Zeta Potential (PZ). The structural and textural characteristics of hybrid materials ranged for each sol-gel route and template employed extraction process resulting in materials with different adsorption capacities. The silicas without functionalization were unable to adsorb the tannin compounds in aqueous solution, whereas the silica functionalized with APTES demonstrated the potential of the adsorbent for the tested compounds, with removals above of 80%. Differences in adsorption capacities between functionalized silica with and without molecular imprinting were observed where the unprinted silica had a higher adsorption of tannins, indicating that more studies are needed to find a process of efficient template extraction to improve adsorption capacity to the imprinted materials. Further, the silicas with improved adsorption capacity could adsorb the tannin compounds for several consecutive cycles of adsorption.

O processamento de peles para a fabricação de couro utiliza uma mistura complexa de substâncias - dentre elas, os taninos - que torna o tratamento de águas residuais difícil e oneroso. Vários estudos estão sendo conduzidos na tentativa de melhorar o tratamento e até mesmo reutilizar o efluente tratado. Neste trabalho foi avaliado o desenvolvimento de adsorventes funcionais sintetizados pelo método solgel e dotados de impressão molecular, para adsorção de compostos de taninos. Por serem de fácil preparação, os materiais híbridos obtidos viabilizam a sua produção para o uso como sólidos adsorventes. A caracterização dos materiais híbridos orgânico-inorgânico obtidos foi realizada por análise de Porosimetria de nitrogênio (BET), Espalhamento de raios-X a baixo ângulo (SAXS), Espectroscopia de refletância difusa no UV-vis (DRS), Espectroscopia de infravermelho com transformada de Fourier (FT-IR) e Potencial Zeta (PZ). As características estruturais e texturais dos materiais híbridos gerados variaram para cada rota sol-gel e processo de extração de template empregado, resultando em materiais com diferentes capacidades de adsorção. As sílicas sem funcionalização não foram capazes de adsorver os compostos de tanino em solução aquosa, enquanto que as sílicas funcionalizadas com APTES demonstraram sua potencialidade como adsorvente para os compostos testados, atingindo remoções superiores a 80%. Diferenças nas capacidades de adsorção entre as sílicas funcionalizadas com e sem impressão molecular também foram observadas, onde a sílica sem impressão apresentou uma adsorção superior de taninos, indicando que mais estudos são necessários para encontrar um processo de extração eficiente do template. É importante salientar que as sílicas que obtiveram a maior capacidade de adsorção, puderam adsorver os compostos de taninos por vários ciclos consecutivos. / The processing of hides for leather manufacturing uses a complex mix of chemicals that makes the wastewater treatment difficult and costly. Several studies are being conducted in attempt to improve the treatment and even reuse the treated effluent. This study evaluated the development of functional adsorbent synthesized by the molecular imprinting method in a sol-gel matrix, for adsorbing tannin compounds. Easy to prepare, hybrid materials obtained enable their production for use as solid adsorbents. The characterization of organic-inorganic hybrid materials obtained was performed by nitrogen porosimetry analysis (BET), small-angle X-ray scattering (SAXS), diffuse reflectance spectroscopy (DRS), Fourier-Transform Infrared Spectroscopy (FT-IR) and Zeta Potential (PZ). The structural and textural characteristics of hybrid materials ranged for each sol-gel route and template employed extraction process resulting in materials with different adsorption capacities. The silicas without functionalization were unable to adsorb the tannin compounds in aqueous solution, whereas the silica functionalized with APTES demonstrated the potential of the adsorbent for the tested compounds, with removals above of 80%. Differences in adsorption capacities between functionalized silica with and without molecular imprinting were observed where the unprinted silica had a higher adsorption of tannins, indicating that more studies are needed to find a process of efficient template extraction to improve adsorption capacity to the imprinted materials. Further, the silicas with improved adsorption capacity could adsorb the tannin compounds for several consecutive cycles of adsorption.

Orientador: Fabio Augusto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T13:57:50Z (GMT). No. of bitstreams: 1 Silva_RaquelGomesdaCosta_D.pdf: 2096184 bytes, checksum: a4a32e68eebe713c6f80bc5415484d51 (MD5) Previous issue date: 2009 / Resumo: Esse trabalho apresenta o desenvolvimento de materiais sorventes com impressão molecular, para utilização na Extração em Fase Sólida (SPE) a partir da tecnologia sol-gel. No capítulo 1 foi preparado um material com impressão molecular seletivo para metilxantinas, utilizando-se o processo sol-gel. Posteriormente, esse material foi aplicado na extração de cafeína em águas e urina humana, seguido de análise cromatográfica. No capítulo 2, foi sintetizado um ormosil (sílica organicamente modificada) seletivo para fenobarbital. Nessa etapa, como molécula molde foi utilizado um análogo estrutural (ácido barbitúrico) ao analito alvo. O material foi aplicado na determinação de fenobarbital em plasma humano, demonstrando ser seletivo para esse composto. No capítulo 3 foi relatado o preparo de um ormosil impresso molecularmente seletivo para compostos triazínicos. Esse material foi aplicado com sucesso na determinação de simazina, propazina e atrazina em amostras de caldo de cana. Paralelamente, o material preparado em laboratório foi comparado ao material comercial seletivo para triazinas. Ambos materiais demonstraram ser seletivo para esses compostos. Os materiais preparados a partir do processo sol-gel apresentaram potencialidade na determinação de diferentes analitos alvo. / Abstract: This work presents the development of sorbent materials with molecular imprinting for use in Solid Phase Extraction (SPE) through sol-gel technology. In chapter 1, a molecularly imprinted material selective for methylxanthines was prepared, using the sol-gel process. Subsequently, this material was used in the extraction of caffeine from water and human urine, followed by chromatographic analysis. In Chapter 2, an ormosil (organically modified silica) selective for phenobarbital was synthesized. For this, a analogue structural was used as template (barbituric acid) for the target analyte. The material was applied to the determination of phenobarbital in human plasma, proving to be selective for this compound. In Chapter 3 the preparation of a imprinted ormosil selective for triazine is reported. This material has been successfully applied for the determination of simazine, atrazine and propazine in samples of sugar cane juice. In addition, the material prepared in the laboratory was compared to commercial material selective for triazines. Both materials were shown to be selective for these compounds. The materials prepared by the sol-gel process showed potential for the determination of different target analytes. / Doutorado / Quimica Analitica / Doutor em Ciências

The synthesis and evaluation of a molecularly imprinted polymer has been undertaken using an oxazine-based tryptophanamide transition state analogue (TSA) as template. An efficient route to the synthesis of oxazine-based TSAs for the reaction of pyridoxamine and indole-3-pyruvic acid has been established, with yields of up to 80%. NMR titration studies were performed to examine the interactions between the functional monomer, methacrylic acid and the template. Complexation of the template by functional monomer in the presence of crosslinker showed an apparent KD of 0.63-0.79 ± 0.04 M (293 K, acetonitrile-d3) based upon the chemical shift of the template amide protons. TSA-imprinted and non-imprinted reference polymers were synthesized by free radical polymerization in acetonitrile. Polymer monoliths were ground and fractionated into a 25-63 μm size range. Polymer-ligand recognition studies were conducted using the polymers as HPLC stationary phases. An imprinting factor (IF) of 2.93 was observed for the TSA, indicating the selectivity of the imprinted sites for the template. Studies using the D- and L-enantiomers of the phenylalaninamide analogue of the template showed enantioselectivity in the case of the imprinted polymer, α = 1.10, though not in the case of the non-imprinted reference polymer (1.00). Using UV-spectroscopy based polymer-ligand binding studies, a maximum theoretical capacity (Bmax) of 0.059 ± 0.004 mmol·g-1 was observed for the imprinted polymer. Conclusively, an imprinted polymer with binding sites selective for the TSA was successfully prepared and shall subsequently be studied with respect to its capacity to catalyse the transamination reaction between pyridoxamine and indole-3-pyruvic acid to yield pyridoxal and tryptophan.

Partitioning of poly(ethyleneglycol) (PEG) molecules in 2-D and 3-D systems is presented as a self-assembly approach for controlling non-specific adsorption of proteins at interfaces. Lateral restructuring of multi-component Langmuir monolayers to accommodate adsorbing proteins was investigated as a model 2-D system. Ferritin adsorption to monolayers containing cationic, nonionic, and PEG bearing phospholipids induced protein sized binding pockets surrounded by PEG rich regions. The number, size, and distribution of protein imprint sites were controlled by the molar ratios, miscibility, and lateral mobility of the lipids. The influence of PEG chain length on the ternary monolayer restructuring and protein distribution was also investigated using DSPE-PEGx (x= 7, 16, 22). Monolayer miscibility analysis demonstrated that longer PEG chains diminished the condensed phase formation for a fixed ratio of lipids. Thus, incorporation of longer PEG chains, intended to diminish protein adsorption outside of the imprint sites of cationic / non-ionic lipids, leads to dramatic changes in monolayer phase behavior and protein distribution in this 2-D system. The assembly of PEG-amphiphiles at elastomer surfaces and subsequent protein adsorption was investigated as a model 3-D system. Polydimethylsiloxane (PDMS) substrates were modified with block copolymers comprised of PEG and PDMS segments by two methods: (1) the block copolymer was mixed with PDMS during polymerization; (2) the block copolymer diffused into solvent swollen PDMS monoliths. Hydrophilic surfaces resulted for both approaches that, for 600 D block copolymer, exhibited up to 85% reduction in fibrinogen adsorption as compared to native PDMS. Higher MW block copolymers (up to 3000 D) resulted in less hydrophilic surfaces and greater protein adsorption, presumably due to diffusion limitations of copolymer in the PDMS monolith. All modified PDMS surfaces were dynamic and restructured when cycled between air and water. PDMS transparency also decreased with increase in block copolymer concentration for both methods, limiting this modification protocol for applications requiring high polymer transparency. The 2-D system presents a bottom-up approach, where adsorbing protein constructs the binding site, while the 3-D system presents a top down approach, where protein-binding elements may be introduced into the PEG-bearing polymer for fabrication of surfaces with controlled protein adsorption.

<p>Despite the long history of topical eye drops and their use in delivering therapeutic agents to the anterior of the eye, efficient sustained delivery continues to be an elusive goal. The robust and effective clearance mechanisms that the eye is endowed with are significant delivery challenges and result in short drug residence times and low ocular bioavailability. The work carried out in this thesis focused on developing, synthesizing and characterizing silicone hydrogels and evaluating their potential as drug eluting inserts for more effective delivery of ocular pharmaceuticals. The first strategy (Chapter 2) focused on incorporating a novel hydrogel additive, hyaluronic acid, to promote hydrogel-drug ionic interactions that can function to increase drug loading and subsequent release dosage. Hydrogels composed of a hydrophilic monomer, N,N-dimethlacrylamide (DMA) or 2-hydroxyethyl methacrylate (HEMA), and a hydrophobic monomer, methacryloxypropyltris(trimethylsiloxy)silane (TRIS), were used as model contact lenses. By combining ionic interactions with molecular imprinting techniques within a single hydrogel, it was shown that this can produce a compound effect on drug uptake and release. Although greater control over release dosage was achieved, there was limited capacity for these materials to delivery timolol for extended periods with drug release occurring rapidly over a period of 1-2 days. However, there were clear differences in the release duration from the p(DMA-<em>co</em>-TRIS) and p(HEMA-<em>co</em>-TRIS) hydrogel formulations. Therefore, the second study (Chapter 3) aimed to better understand the relationship between the hydrogel chemical composition and the resultant material properties on the drug release characteristics. A range of hydrogels were synthesized with varying hydrophilic and hydrophobic monomers, which were then characterized by their water content, transparency, optical haze and surface wettability. The previous generation materials were evolved by incorporating a modified siloxy methacrylate TRIS(OH), a methacrylated polydimethylsiloxane macromonomer (mPDMS) and a polymerizable silicone surfactant (ACR). The properties of the hydrogels were dramatically affected by the nature and relative contribution of hydrophobic and hydrophilic monomers. The release of dexamethasone (DEX), an anti-inflammatory medication, was shown to vary significantly depending on the hydrogel formulations; often displaying faster release in high water content materials and slow release in low water content hydrogels. The mechanism of diffusion for lipophilic DEX in these hydrogel systems appeared to be through the internal aqueous network channels within the bulk. Over the range of hydrogels formulations that were tested, the release from them varied from approximately seven days to greater than two weeks.</p> / Master of Applied Science (MASc)

Advantages such as chemical, mechanical and thermal stability together with high selectivity for the templated analyte render molecularly imprinted polymers MIPs interesting alternatives to routinely applied separation materials or antibodies. Nevertheless, many factors such as the choice of functional monomer, cross-linker, and porogenic solvent, as well as the ratio between template, functional monomer, and cross-linker will affect the resulting imprinting efficiency and polymer particle size and morphology. The research described in this thesis contributes to the development of new synthetic strategies for the generation of imprinted micro- and nanospheres for 17beta-estradiol (E2) focusing on accurate control and optimization of the governing parameters for precipitation polymerization, including the polymerization temperature and the cross-linker, yielding a one-step synthetic approach with superior control on the bead diameter, shape, monodispersity and imprinting efficiency. Thus synthesized imprinting materials for E2 were successfully applied in HPLC separation, solid phase extraction and radioligand binding assays. As the optimization of imprinted materials is based on fundamental understanding of the binding site properties, the investigations is aimed at establishing a more rational basis for further tailoring imprinted materials to the desired analytical application. The relationships between the particle porosity and rebinding properties were detailed, providing useful guidelines for controlling the particle properties for the desired application including, SPE pre-concentration, HPLC separations, and biomimetic binding assays. Furthermore, analytical techniques (1H-NMR and IR, etc.) and molecular modeling were combined in this thesis to facilitate advanced understanding of the fundamental principles governing selective recognition of molecularly imprinted polymers at a molecular level. The molecular interactions involved in the templating process of molecularly imprinted polymers based on the self-assembly approach were simulated in molecular dynamic simulation model by building a modeling system include all the imprinting components with correct ratio, which has never been reported before. Molecular level interactions such as hydrogen bonding, π-π stacking interactions as well as the free energy governing complex formation of E2 with the functional monomers 4-vinylpyridine (4VP) and methacrylic acid (MAA), and the cross-linker divinylbenzene (DVB) were discussed.

The syntheses and evaluation of oxidovanadium(IV) complexes as catalysts for the oxidation of refractory organosulfur compounds in fuels is presented. The sulfones produced from the oxidation reaction were removed from fuel oils by employing molecularly imprinted polymers (MIPs). The oxidovanadium(IV) homogeneous catalyst, [V ͥ ͮ O(sal-HBPD)], as well as its heterogeneous polymer supported derivatives, poly[V ͥ ͮ O(sal-AHBPD)] and poly[V ͥ ͮ O(allylSB-co-EGDMA)], were synthesized and fully characterized by elemental analysis, FTIR, UV-Vis, XPS, AFM, SEM, BET and single crystal XRD for [V ͥ ͮ O(sal-HBPD)]. The MIPs were also characterized by elemental analysis, FTIR, SEM, EDX and BET. The catalyzed oxidation of fuel oil model sulfur compounds, thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT), was conducted under batch and continuous flow processes at 40°C by using tert-butylhydroperoxide (t-BuOOH) as oxidant. The continuous flow oxidation process presented the highest overall conversions and very high selectivity for sulfones. Maximum oxidation conversions of 71%, 89%, 99% and 88% was achieved for TH, BT, DBT and 4,6-DMDBT respectively when poly[V ͥ ͮ O(allylSB-co-EGDMA)] was employed at a flow-rate of 1 mL/h with over 90% sulfone selectivity. The process was further applied to the oxidation of hydro-treated diesel containing 385 ± 4.6 ppm of sulfur (mainly dibenzothiophene and dibenzothiophene derivatives), and this resulted to a high sulfur oxidation yield (> 99%), thus producing polar sulfones which are extractible by polar solid phase extractants. Adsorption of the polar sulfone compounds was carried-out by employing MIPs which were fabricated through the formation of recognition sites complementary to oxidized sulfur-containing compounds (sulfones) on electrospun polybenzimidazole (PBI) nanofibers, cross-linked chitosan microspheres and electrospun chitosan nanofibers. Adsorption of benzothiophene sulfone (BTO₂), dibenzothiophene sulfone (DBTO₂) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO₂) on the various molecularly imprinted adsorbents presented a Freundlich (multi-layered) adsorption isotherm which indicated interaction of adsorbed organosulfur compounds. Maximum adsorption observed for BTO₂, DBTO₂ and 4,6-DMDBTO₂ respectively was 8.5 ± 0.6 mg/g, 7.0 ± 0.5 mg/g and 6.6 ± 0.7 mg/g when imprinted chitosan nanofibers were employed, 4.9 ± 0.5 mg/g, 4.2 ± 0.7 mg/g and 3.9 ± 0.6 mg/g on molecularly imprinted chitosan microspheres, and 28.5 ± 0.4 mg/g, 29.8 ± 2.2 mg/g and 20.1 ± 1.4 mg/g on molecularly imprinted PBI nanofibers. Application of electrospun chitosan nanofibers on oxidized hydro-treated diesel presented a sulfur removal capacity of 84%, leaving 62 ± 3.2 ppm S in the fuel, while imprinted PBI electrospun nanofibers displayed excellent sulfur removal, keeping sulfur in the fuel after the oxidation/adsorption below the determined limit of detection (LOD), which is 2.4 ppm S. The high level of sulfur removal displayed by imprinted PBI nanofibers was ascribed to hydrogen bonding effects, and π-π stacking between aromatic sulfone compounds and the benzimidazole ring which were confirmed by chemical modelling with density functional theory (DFT) as well as the imprinting effect. The home-made pressurized hot water extraction (PHWE) system was applied for extraction/desorption of sulfone compounds adsorbed on the PBI nanofibers at a flow rate of 1 mL/min and at 150°C with an applied pressure of 30 bars. Application of molecularly imprinted PBI nanofibers for the desulfurization of oxidized hydro-treated fuel showed potential for use in refining industries to reach ultra-low sulfur fuel level, which falls below the 10 ppm sulfur limit which is mandated by the environmental protection agency (EPA) from 2015.