>Magister Scientiae - MSc / Nitric oxide (NO) plays a vital role as a biological messenger in biological systems. However, NO detection and quantification have always posed significant complications. There is, therefore, a need to develop new materials or technologies that can be used for sampling and determination of NO species in aqueous environments. The use of Schiff base complexes incorporated onto electrodes to make an electrochemical sensor has been explored as an effective method for the determination and quantification of NO in aqueous solutions. The motivation is based on the precedent of denatured cytochrome C as a suitable complexing site for electron-rich species. The ligands and metals complexes used in this work aim to mimic the square planar arrangement of Fe in denatured cytochrome. It is believed that the accessibility of the haem Fe in this configuration is at the heart of the analyte interactions leading to favourable signal transduction. In preparing the Schiff base and corresponding metal complexes, a microwave-assisted synthetic method, was employed. / 2025

O presente trabalho teve como principal objetivo a produção por eletrofiação de nãotecidos compostos por fibras ultrafinas à base de policaprolactona (PCL) e cloreto de N-(2-hidroxil)-propil-3-trimetilamônio quitosana (QCh) potencialmente aplicáveis no tratamento de lesões de pele. Para tal, QCh foi sintetizado pela reação entre cloreto de glicidiltrimetilamônio (CGTMA) e quitosana em meio ácido sob irradiação de micro-ondas. Tanto a quitosana de partida como os derivados obtidos foram caracterizados por espectroscopia na região do infravermelho (FTIR), espectroscopia de ressonância magnética nuclear de hidrogênio (RMN 1H), viscosimetria capilar, solubilidade em função do pH, análise termogravimétrica e difração de raios-X. Planejamento fatorial 23 com ponto central e metodologia de superfície de resposta foram aplicados para avaliar o efeito dos parâmetros reacionais razão molar CGTMA/Q, temperatura e tempo reacionais sobre o grau médio de quaternização (GQ-), viscosidade intrínseca e sobre o rendimento reacional. Os resultados mostraram que a razão molar CGTMA/Q foi o fator que mais influenciou as variáveis resposta avaliadas e que a síntese realizada em reator micro-ondas possibilitou a produção de QCh com elevado grau médio de quaternização (GQ-> 70%) em tempo expressivamente inferior (≤30 min.) quando comparado à reação empregando aquecimento convencional (> 4 h). Na etapa subsequente, QCh com diferentes características estruturais (grau médio de quaternização (GQ-) e grau médio de polimerização (GPv-), a saber QCh1 (GQ-= 47,3 %; GPv- = 2218) e QCh2 (GQ-= 71,1 %; GPv- = 1427, foram dissolvidos em diferentes proporções mássicas com poli(ε-caprolactona) (PCL/QCh: 100/0 - 70/30) em solução ácido acético/ácido fórmico 60/40 (v/v) e eletrofiados. Os nãotecidos obtidos foram caracterizados quanto ao diâmetro médio e grau de orientação das fibras, porosidade e espessura, caráter hidrofílico/hidrofóbico das superfícies, capacidade de absorção de água, transmissão de vapor de água, além de cristalinidade e propriedades térmicas e mecânicas. Experimentos in vitro também foram realizados para avaliar a suscetibilidade à degradação enzimática, citotoxicidade em relação às linhagens de células de fibroblastos dérmicos humanos neonatais (HDFn) e queratinócitos humanos (HaCaT) e adesão dessas células na superfície dos nãotecidos. Os resultados dessa etapa revelaram que de acordo com as características estruturais do QCh e com a quantidade desse derivado na blenda PCL/QCh, os nãotecidos obtidos apresentaram fibras com diferentes diâmetros médio (175 nm - 415 nm) e graus de orientação, além de exibirem diferentes porosidade (57,0 % - 81,6 %) e capacidade de hidratação (175 % - 425 %). Os ensaios de tração revelaram que os nãotecidos apresentaram equilíbrio entre capacidade de alongação e tensão na ruptura nos estados seco e após hidratação, sendo que altos valores de tensão na ruptura (> 4 MPa) e alongação (> 120 %) foram observados nos nãotecidos PCL/QCh 90/10. A cristalinidade e a estabilidade térmica dos nãotecidos PCL/QCh foram progressivamente reduzidas com o aumento da concentração de QCh. Os nãotecidos não foram suscetíveis à degradação por lisozima e os ensaios de citotoxidade in vitro mostraram que todos os materiais, exceto PCL/QCh2 70/30, não apresentaram caráter citotóxico em relação às linhagens de células de fibroblastos (HDFn) e queratinócitos humanos (HaCaT). A presença de QCh conferiu caráter hidrofílico à superfície dos nãotecidos favorecendo a adesão e a proliferação dessas células, o que não ocorreu no nãotecido composto somente por PCL. A análise global dos resultados indicou que os nãotecidos PCL/QCh1 90/10 e PCL/QCh2 90/10 foram os que apresentaram características mais promissoras para serem utilizados como curativos, visto que possuem caráter hidrofílico, elevada capacidade de hidratação, estabilidade em meio aquoso, resistência mecânica tanto secos como hidratados, além de não apresentarem caráter citotóxico e favorecerem a adesão e proliferação de fibroblastos e queratinócitos. / The main purpose of this work was the development of electrospun nonwovens composed by ultrathin fibers based on polycaprolactone (PCL) and N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (QCh) potentially useful as wound dressings. QCh was synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) and chitosan (Ch) in acid medium under microwave irradiation. The parent chitosan, as well as the resulting derivatives, were characterized by Fourier transform infrared (FTIR) and 1H NMR spectroscopy, capillary viscometry, thermogravimetric analysis (TGA), X-ray diffraction and with respect to water-solubility as a function of pH. Full-factorial 23 central composite design and response surface methodology (RSM) were applied to evaluate the effects of molar ratio GTMAC/Ch, reaction time and temperature on the reaction yield, average degree of quaternization (DQ-) and intrinsic viscosity ([η]) of QCh. Results showed that the molar ratio GTMAC/Ch was the most important factor affecting the response variables and that microwave-assisted synthesis allowed the production of highly substituted QCh ((DQ- > 70%)) at a significantly shorter time (≤ 30 min.) as compared to conventional reaction procedures (> 4 h). Following, two samples of QCh possessing different characteristics, i.e. average degree of quaternization (DQ-) and viscosity average degree of polymerization (DPv-), namely QCh1 ( DQ- = 47.3 %; DPv- = 2218) and QCh2 (DQ-= 71.1 %; DPv- = 1427), were synthesized, blended with PCL in acetic acid/formic acid (60/40 v/v) and electrospun into fibrous nonwovens. The PCL/QCh nonwovens were characterized in terms of morphology, surface properties, water absorption capacity, moisture permeation, thermal and tensile properties. In vitro experiments were carried out to evaluate the susceptibility of PCL/QCh nonwovens to enzymatic degradation, cytotoxicity toward neonatal human dermal fibroblasts (HDFn) and human keratinocytes (HaCaT), and adhesion of these cells on nonwoven\'s surface. According to the characteristics of QCh derivative, mainly DQ- and (DPv) ?, and to the QCh content on the resulting PCL/QCh nonwoven, the nanofibers displayed different average diameter (175 nm - 415 nm), and the nonwovens exhibited variable porosity (57.0 % - 81.6 %) and swelling capacity (175 % - 425 %). The tensile tests revealed that the nonwovens present a balance between elasticity and strength under both, dry and hydrated state, the higher tensile strength (> 4 MPa) and elongation (> 120 %) being observed for PCL/QCh 90/10 nonwovens. The crystallinity and thermal stability of PCL/QCh nonwoven decreased with increasing QCh content. The PCL/QCh nonwovens were not susceptible to lysozyme degradation and all PCL/QCh nonwovens, except PCL/QCh2 70/30, were non-cytotoxic toward fibroblasts (HDFn) and keratinocyte (HaCaT). The presence of QCh conferred a hydrophilic character to the surface of the nonwoven, favoring HDFn and HaCaT cells adhesion and spreading, which did not occur in the nonwoven composed only by PCL. Taking into account the whole set of results, it is concluded that the PCL/QCh1 90/10 and PCL/QCh2 90/10 nonwovens showed the most promising characteristics to be used as wound dressings, since they have hydrophilic character, high hydration capacity, stability in aqueous medium, mechanical resistance, in dry and hydrated states, besides they were non-cytotoxic and favored the adhesion and proliferation of fibroblasts and keratinocytes.

Die grundlegende Frage- bzw. Problemstellung der vorliegenden Arbeit war die Entwicklung innovativer Synthesemethoden für die nanoskalige, anorganische Festkörper- und Materialchemie, sowie die umfassende Charakterisierung der neuartigen Materialien und deren Untersuchung hinsichtlich potentieller Anwendungen. Die Arbeit umfasst dabei zwei große Themengebiete: Das Kapitel Bismutbasierte Nanoröhren beschreibt detailliert die neuartige Synthese doppelwandiger Bismut-Nanoröhren (engl. Double Walled Bismuth Nanotubes, DWBiNTs) bei Raumtemperatur, durch die Umsetzung von Bismutmonoiodid mit n-Butyllithium (n-BuLi) zu elementarem Bismut. Elektronenmikroskopische Untersuchungen des resultierenden feinen schwarzen Pulvers zeigen homogen strukturierte, stark agglomerierte, anisotrope Partikel mit Längen von mehreren hundert Nanometer, welche an den Enden geöffnet vorliegen und zudem einen „zwiebelartigen“ Aufbau mit einem einheitlichen inneren Durchmesser von ca. 4,5 nm sowie einen äußeren Durchmesser von ca. 6 nm aufweisen (Abbildung 1 A – C). Auf Grundlage dieser Erkenntnisse wurden von Rasche quantenchemische Rechnungen am Modell einer (34,0)@(40,0)-DWBiNT durchgeführt, aus denen neben einer hexagonal facettierten Querschnittsgeometrie (Abbildung 1 D) durch Rechnungen der elektronischen Eigenschaften eine direkte Bandlücke von 0,5 eV hervorgeht, womit es sich bei diesen Strukturen um Halbleiter handeln sollte. Im Gegensatz zu bislang bekannten Synthesemethoden für Bi-Nanoröhren kann die in der vorliegenden Arbeit entwickelte Syntheseroute als chemische Top-Down-Bottom-Up-Methode verstanden werden. Hiermit soll die Kaskade des Herauslösens der im Festkörper vorgeprägten Strukturen (chemisch Top-Down) gefolgt von deren Reorganisation zu nanoskopischen Objekten (klassisch Bottom-Up) verdeutlicht werden. Diese Herangehens-weise der Niedertemperaturreduktion klassischer Festkörperverbindungen ist bislang einzigartig und konnte basierend auf den Ergebnissen der vorliegenden Arbeit innerhalb des Arbeitskreises bereits erfolgreich auf intermetallische Phasen übertragen werden. Es konnte ferner gezeigt werden, dass es durch die milde Oxidation von DWBiNTs im O2-Strom möglich ist, unter Erhalt der Morphologie gezielt Nanoröhren der unter Normalbedingungen metastabilen β-Modifikation von Bi2O3 zu synthetisieren. Diese wurden in Zusammenarbeit mit dem Kurt-Schwabe-Institut für Mess- und Sensortechnik e.V. Meinsberg hinsichtlich ihrer gassensitiven Eigenschaften untersucht. Während die oxidischen Nanoröhren keine Sensitivität gegenüber CO und nur eine geringe H2-Sensitivität aufweisen, zeigt sich eine signifikante Widerstandserhöhung mit sinkendem Sauerstoffpartialdruck im Gasgemisch. Diese Befunde zeigen eine mögliche, bislang nicht untersuchte Anwendung von Bi2O3 als Sauerstoffsensor. Das Kapitel Mikrowellenunterstützte Niedertemperatursynthese der vorliegenden Arbeit widmet sich – basierend auf dem Polyolprozess (Abbildung 2) – der zeit- und energieeffizienten Synthese der intermetallischen Phasen BiNi, Bi3Ni und BiRh, welche durch herkömmliche metallurgische Hochtemperaturschmelz- oder sinterprozesse nur schwer zugänglich sind. Besonderer Schwerpunkt liegt in der gezielten Synthese mikro- und nanostrukturierter Proben. Die intermetallische Phase Bi3Ni kann röntgenographisch phasenrein in Form homogener stäbchenförmiger Partikel mit Abmessungen von ca. 200 nm x 600 nm, so genanntes submikroskaliges Bi3Ni, synthetisiert werden (Abbildung 3 A). Ebenso erfolgreich gestaltet sich die Synthese der nickelreicheren Phase BiNi in Form von Nadeln mit Durchmessern von wenigen Nanometern und Längen von mehreren Mikrometern sowie der binären Phase BiRh in Gestalt wohl definierter hexagonal facettierter, plättchenartiger Partikel mit einem mittleren Durchmesser von ca. 50 nm und Dicken < 10 nm (Abbildung 3 B, C). In Kooperation mit der Professur Anorganische Chemie I der TU Dresden konnte am Beispiel der intermetallischen Phase Bi3Ni erfolgreich die gezielte Einstellung der Partikelgröße und –morphologie unter Verwendung des mesoporösen Oxids SBA-15 als Exotemplat gezeigt werden. Die herausgelösten Proben zeigen röntgenographisch phasenreine, agglomerierte, sphärische Nanopartikel mit einem Durchmesser von < 8 nm. Die statische Magnetisierung sowie die Transporteigenschaften an den morphologisch unterschiedlichen Proben des Typ-II Supraleiters Bi3Ni wurden in Kooperation mit dem Hochfeld-Magnetlabor des Helmholtz-Zentrum Dresden-Rossendorf untersucht. Es zeigt sich, dass durch chemische Nanostrukturierung physikalische Eigenschaften generiert werden, welche Volumenproben derselben Substanz nicht aufweisen: Die als unvereinbare Antagonisten angesehenen Grundzustände Ferromagnetismus und Supraleitung können in mesoskopischem Bi3Ni nicht nur koexistieren, sondern stärken einander sogar (Abbildung 4). Diese Ergebnisse zeigen beispielhaft, dass Partikelgrößen im Zusammenspiel mit chemischer Substrukturierung in quasi-1D-Bindungssystemen essentiell für das Auftreten neuartiger Quanteneffekte sind. In Zusammenarbeit mit dem Max-Planck-Institut für Chemische Physik fester Stoffe wurden die röntgenographisch phasenreinen Proben von BiNi (Nadeln), Bi3Ni (Stäbchen) und BiRh (hexagonale Nanoplättchen) hinsichtlich ihrer potentiellen Anwendung zur Semihydrierung von Acetylen untersucht. Für die Proben des Systems Bi/Ni kann keinerlei katalytische Aktivität gemessen werden, wohingegen die katalytischen Eigenschaften der BiRh Nanopartikel für die Semihydrierung von Acetylen hervorragend sind. So weisen die hexagonalen Nanoplättchen eine außerordentlich hohe Selektivität gegenüber Acetylen sowie eine sehr gute Langzeitstabilität, im Vergleich zu einem kommerziell erhältlichen Pd/Al2O3 Katalysator, auf. Auf Basis der im Rahmen dieser Arbeit entwickelten und in ihren Ergebnissen (Phase, Reinheit, verschiedene Morphologien) kontrollierbaren sowie zeit- und energieeffizienten reduktiven Solvothermalmethode zur Synthese von intermetallischen Verbindungen ist der Zugang zu weiteren neuartigen, mehrkomponentigen, metallischen Materialien, welche durch klassische metallurgische Hochtemperaturschmelz- oder -sinterprozesse nur schwer oder gar nicht zugänglich sind, möglich. Allgemein kann das beschriebene Verfahren als eine verlässliche, breit anwendbare Methode zur Synthese wohl strukturierter Verbindungen auf chemischem Weg bei Temperaturen bis maximal 250 °C angesehen werden, welches eine große Bandbreite an verschiedenen Einsatzmöglichkeiten bietet.

Ces travaux de thèse portent sur la synthèse et la caractérisation de nanoparticules d’oxyde spinelle à base de cobalt, déposée à la surface de feuillets d’oxyde de graphène réduit. Ces nanocomposites ont pour but de servir de catalyseurs bifonctionnels intégrés à l’électrode à air des batteries lithium-air. La particularité des synthèses présentées repose sur le chauffage micro-onde des précurseurs en milieu aqueux entre 100 et 200 °C. Cette approche originale de chimie douce permet en outre la création de l’interface entre les nanoparticules d’oxyde et les feuillets de graphène directement pendant la synthèse des particules, au lieu de nécessiter une étape supplémentaire de greffage. L’oxyde de cobalt Co3O4 a servi de matériau modèle pour optimiser les différents paramètres de synthèse puis le protocole a été adapté à une série d’oxydes binaires en substituant une partie des atomes de cobalt par du nickel, du manganèse ou encore du fer. La co-précipitation des cations de métaux de transition au sein d’une même phase a été rendue possible grâce à la compréhension des diagrammes de Pourbaix pour ajuster les conditions redox et acido-basiques.Enfin, les propriétés électrocatalytiques des catalyseurs composites vis-à-vis des deux réactions inverses d’ORR et OER ont été testées. L’écart entre les potentiels d’OER et ORR a été diminué de manière significative grâce à la présence des nanoparticules de Co3O4 sur feuillets d’oxyde de graphène réduit, montrant ainsi la réversibilité du catalyseur.Des caractérisations structurales et morphologiques qui ont permis d’établir certains liens entre synthèse, nanostructure et activité électrocatalytique complètent ce travail. / This research work is focused on the design and characterisation of cobalt based oxides nanospinels anchored onto the surface of reduced graphene oxides (RGO) nanosheet, which will serve as bifunctional catalysts for the new generation lithium-air batteries. Whereas nanospinels are relatively simple to synthesize by conventional colloidal routes as nanoparticles dispersed into an aqueous solution, the synthesis we developed relies on a hydrothermal microwave treatment in the 100°C-200°C range. The main challenges of this nano-heterostructures synthesis was to create the interface between the nanoparticles and the RGO directly during the nanoparticles nucleation. RGO are very efficient microwave absorbers and could then convert microwave irradiation into heat in order to trigger precipitation of the spinel at the surface of the RGO sheet.Starting from Co3O4 as proof-of-concept material, the synthesis protocol has been successfully adapted to address binary oxides by substituting cobalt with first row transition metals such as nickel, manganese or iron. The precipitation of binary and ternary oxides was achievable thanks to a good understanding of the Pourbaix diagrams of all cations to adjust the acido-basic and redox conditions.Finally, the electrocatalytic activity of these supported spinel oxides was measured for both the oxygen reduction and oxygen evolution reactions (ORR and OER). The gap between the ORR and the OER potentials was significantly lowered by the presence of Co3O4 nanoparticles on the RGO, thus assuring the reversibility of this catalytic system, which is to be integrated in future scale-up test.

O presente trabalho teve como principal objetivo a produção por eletrofiação de nãotecidos compostos por fibras ultrafinas à base de policaprolactona (PCL) e cloreto de N-(2-hidroxil)-propil-3-trimetilamônio quitosana (QCh) potencialmente aplicáveis no tratamento de lesões de pele. Para tal, QCh foi sintetizado pela reação entre cloreto de glicidiltrimetilamônio (CGTMA) e quitosana em meio ácido sob irradiação de micro-ondas. Tanto a quitosana de partida como os derivados obtidos foram caracterizados por espectroscopia na região do infravermelho (FTIR), espectroscopia de ressonância magnética nuclear de hidrogênio (RMN 1H), viscosimetria capilar, solubilidade em função do pH, análise termogravimétrica e difração de raios-X. Planejamento fatorial 23 com ponto central e metodologia de superfície de resposta foram aplicados para avaliar o efeito dos parâmetros reacionais razão molar CGTMA/Q, temperatura e tempo reacionais sobre o grau médio de quaternização (GQ-), viscosidade intrínseca e sobre o rendimento reacional. Os resultados mostraram que a razão molar CGTMA/Q foi o fator que mais influenciou as variáveis resposta avaliadas e que a síntese realizada em reator micro-ondas possibilitou a produção de QCh com elevado grau médio de quaternização (GQ-&gt; 70%) em tempo expressivamente inferior (&le;30 min.) quando comparado à reação empregando aquecimento convencional (&gt; 4 h). Na etapa subsequente, QCh com diferentes características estruturais (grau médio de quaternização (GQ-) e grau médio de polimerização (GPv-), a saber QCh1 (GQ-= 47,3 %; GPv- = 2218) e QCh2 (GQ-= 71,1 %; GPv- = 1427, foram dissolvidos em diferentes proporções mássicas com poli(&epsilon;-caprolactona) (PCL/QCh: 100/0 - 70/30) em solução ácido acético/ácido fórmico 60/40 (v/v) e eletrofiados. Os nãotecidos obtidos foram caracterizados quanto ao diâmetro médio e grau de orientação das fibras, porosidade e espessura, caráter hidrofílico/hidrofóbico das superfícies, capacidade de absorção de água, transmissão de vapor de água, além de cristalinidade e propriedades térmicas e mecânicas. Experimentos in vitro também foram realizados para avaliar a suscetibilidade à degradação enzimática, citotoxicidade em relação às linhagens de células de fibroblastos dérmicos humanos neonatais (HDFn) e queratinócitos humanos (HaCaT) e adesão dessas células na superfície dos nãotecidos. Os resultados dessa etapa revelaram que de acordo com as características estruturais do QCh e com a quantidade desse derivado na blenda PCL/QCh, os nãotecidos obtidos apresentaram fibras com diferentes diâmetros médio (175 nm - 415 nm) e graus de orientação, além de exibirem diferentes porosidade (57,0 % - 81,6 %) e capacidade de hidratação (175 % - 425 %). Os ensaios de tração revelaram que os nãotecidos apresentaram equilíbrio entre capacidade de alongação e tensão na ruptura nos estados seco e após hidratação, sendo que altos valores de tensão na ruptura (&gt; 4 MPa) e alongação (&gt; 120 %) foram observados nos nãotecidos PCL/QCh 90/10. A cristalinidade e a estabilidade térmica dos nãotecidos PCL/QCh foram progressivamente reduzidas com o aumento da concentração de QCh. Os nãotecidos não foram suscetíveis à degradação por lisozima e os ensaios de citotoxidade in vitro mostraram que todos os materiais, exceto PCL/QCh2 70/30, não apresentaram caráter citotóxico em relação às linhagens de células de fibroblastos (HDFn) e queratinócitos humanos (HaCaT). A presença de QCh conferiu caráter hidrofílico à superfície dos nãotecidos favorecendo a adesão e a proliferação dessas células, o que não ocorreu no nãotecido composto somente por PCL. A análise global dos resultados indicou que os nãotecidos PCL/QCh1 90/10 e PCL/QCh2 90/10 foram os que apresentaram características mais promissoras para serem utilizados como curativos, visto que possuem caráter hidrofílico, elevada capacidade de hidratação, estabilidade em meio aquoso, resistência mecânica tanto secos como hidratados, além de não apresentarem caráter citotóxico e favorecerem a adesão e proliferação de fibroblastos e queratinócitos. / The main purpose of this work was the development of electrospun nonwovens composed by ultrathin fibers based on polycaprolactone (PCL) and N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (QCh) potentially useful as wound dressings. QCh was synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) and chitosan (Ch) in acid medium under microwave irradiation. The parent chitosan, as well as the resulting derivatives, were characterized by Fourier transform infrared (FTIR) and 1H NMR spectroscopy, capillary viscometry, thermogravimetric analysis (TGA), X-ray diffraction and with respect to water-solubility as a function of pH. Full-factorial 23 central composite design and response surface methodology (RSM) were applied to evaluate the effects of molar ratio GTMAC/Ch, reaction time and temperature on the reaction yield, average degree of quaternization (DQ-) and intrinsic viscosity ([&eta;]) of QCh. Results showed that the molar ratio GTMAC/Ch was the most important factor affecting the response variables and that microwave-assisted synthesis allowed the production of highly substituted QCh ((DQ- &gt; 70%)) at a significantly shorter time (&le; 30 min.) as compared to conventional reaction procedures (&gt; 4 h). Following, two samples of QCh possessing different characteristics, i.e. average degree of quaternization (DQ-) and viscosity average degree of polymerization (DPv-), namely QCh1 ( DQ- = 47.3 %; DPv- = 2218) and QCh2 (DQ-= 71.1 %; DPv- = 1427), were synthesized, blended with PCL in acetic acid/formic acid (60/40 v/v) and electrospun into fibrous nonwovens. The PCL/QCh nonwovens were characterized in terms of morphology, surface properties, water absorption capacity, moisture permeation, thermal and tensile properties. In vitro experiments were carried out to evaluate the susceptibility of PCL/QCh nonwovens to enzymatic degradation, cytotoxicity toward neonatal human dermal fibroblasts (HDFn) and human keratinocytes (HaCaT), and adhesion of these cells on nonwoven\'s surface. According to the characteristics of QCh derivative, mainly DQ- and (DPv) ?, and to the QCh content on the resulting PCL/QCh nonwoven, the nanofibers displayed different average diameter (175 nm - 415 nm), and the nonwovens exhibited variable porosity (57.0 % - 81.6 %) and swelling capacity (175 % - 425 %). The tensile tests revealed that the nonwovens present a balance between elasticity and strength under both, dry and hydrated state, the higher tensile strength (&gt; 4 MPa) and elongation (&gt; 120 %) being observed for PCL/QCh 90/10 nonwovens. The crystallinity and thermal stability of PCL/QCh nonwoven decreased with increasing QCh content. The PCL/QCh nonwovens were not susceptible to lysozyme degradation and all PCL/QCh nonwovens, except PCL/QCh2 70/30, were non-cytotoxic toward fibroblasts (HDFn) and keratinocyte (HaCaT). The presence of QCh conferred a hydrophilic character to the surface of the nonwoven, favoring HDFn and HaCaT cells adhesion and spreading, which did not occur in the nonwoven composed only by PCL. Taking into account the whole set of results, it is concluded that the PCL/QCh1 90/10 and PCL/QCh2 90/10 nonwovens showed the most promising characteristics to be used as wound dressings, since they have hydrophilic character, high hydration capacity, stability in aqueous medium, mechanical resistance, in dry and hydrated states, besides they were non-cytotoxic and favored the adhesion and proliferation of fibroblasts and keratinocytes.

Synthesis and bulk analysis of composite ceramic oxide materials and materials with perovskite-defect structure is presented within this work. Syntheses of these advanced ceramics materials were carroed out by using of nonconventional techniques (microwave-assisted hydrothermal synthesis and polycondensation techniques) and by conventional mechanochemical activation followed by high temperature solid state reaction. X-Ray difraction (XRD), Rietveld analysis, scaning microscopy (SEM), microalysis EDS-SEM, thermal analysis (TG), infrared spectroscopy (IR), determination of particles size and specific surface area were used for description of synthesized products. In case of perovskite system based on La-Sr-Fe-Ti-O electrochemical properties were studied. Part of work was focused on chemical analysis of synthesized composite oxide materials and decomposition hard structured products by using of nonconventional fields.

No / A library of 53 benzimidazole derivatives, with substituents at positions 1, 2 and 5, were synthesized and screened against a series of reference strains of bacteria and fungi of medical relevance. The SAR analyses of the most promising results showed that the antimicrobial activity of the compounds depended on the substituents attached to the bicyclic heterocycle. In particular, some compounds displayed antibacterial activity against two methicillin-resistant Staphylococcus aureus (MRSA) strains with minimum inhibitory concentrations (MICs) comparable to the widely-used drug ciprofloxacin. The compounds have some common features; three possess 5-halo substituents; two are derivatives of (S)-2-ethanaminebenzimidazole; and the others are derivatives of one 2-(chloromethyl)-1H-benzo[d]imidazole and (1H-benzo[d]imidazol-2-yl)methanethiol. The results from the antifungal screening were also very interesting: 23 compounds exhibited potent fungicidal activity against the selected fungal strains. They displayed equivalent or greater potency in their MIC values than amphotericin B. The 5-halobenzimidazole derivatives could be considered promising broad-spectrum antimicrobial candidates that deserve further study for potential therapeutic applications.

<p>This thesis describes the design, synthesis and evaluation of novel chalcogenide antioxidants. </p><p>A computational model for the prediction of antioxidant properties of chalcogen-containing antioxidants has been developed. The model has been used to probe the relationship between geometry, chalcogen substitution and activity for a series of α-tocopherol analogues of varying ring size and chalcogen substitution. </p><p>A series of simple diaryltellurides and aryl-alkyl tellurides have been synthesised. The selenium analogue of α-tocopherol has been synthesised in eleven steps and 6.5% total yield, with formation of the selenacycle by homolytic substitution at selenium as the key step. Tentative steps have been taken towards the construction of the tellurotocopherol structure by microwave-assisted radical cyclisation methodologies.</p><p>A combination of EPR and kinetic studies has been used to assess the antioxidant characteristics of selenotocopherol. A two-phase lipid peroxidation model revealed that the selenotocopherol is not catalytically regenerable. The same model has been used to assess the cooperativity of mixtures of tellurides with α-tocopherol and an aqueous thiol. It was seen that combinations of α-tocopherol with tellurides incorporating phenols displayed synergistic properties, and the mechanistic implications of this are discussed. </p><p>DSC measurements have been used to assess the antioxidant activity of tellurides together with coantioxidants in melts of polypropylene. The tellurides display excellent activity together with thiol or a sterically hindered phenol antioxidant. In chemiluminescence studies performed at lower temperatures, the telluride mixtures still outperform commercial blends, but to a lesser extent. In a synthetic oil a telluride has demonstrated promising antioxidant properties together with a thiol or phenolic antioxidant. However, under more realistic test conditions the telluride acts instead as a prooxidant. Some tellurides have been evaluated as antioxidants in paper. Water-soluble tellurides appear to function better than lipophilic tellurides, but neither is comparable in activity to α-tocopherol.</p>

New methods have been developed for the synthesis of bicyclic β-lactams and 2-pyridinones by combining acyl Meldrum’s acids and Δ2-thiazolines. The 2-pyridinones were synthesised both in solution using conventional heating or microwave assisted heating as well as by solid supported chemistry. The compounds (pilicides) were designed to interfere with the assembly of pili in uropathogenic E. coli by inhibiting the periplasmic chaperones. The affinity of the pilicides to the chaperones was investigated with surface plasmon resonance technique (Biacore) and with relaxation-edited 1H NMR spectroscopy experiments. Finally, the pilicides were investigated for their ability to inhibit pili formation in uropathogenic E. coli in a hemagglutination assay, where members of the 2-pyridinone family proved to be able to cause depiliation.

This thesis describes the design, synthesis and evaluation of novel chalcogenide antioxidants. A computational model for the prediction of antioxidant properties of chalcogen-containing antioxidants has been developed. The model has been used to probe the relationship between geometry, chalcogen substitution and activity for a series of α-tocopherol analogues of varying ring size and chalcogen substitution. A series of simple diaryltellurides and aryl-alkyl tellurides have been synthesised. The selenium analogue of α-tocopherol has been synthesised in eleven steps and 6.5% total yield, with formation of the selenacycle by homolytic substitution at selenium as the key step. Tentative steps have been taken towards the construction of the tellurotocopherol structure by microwave-assisted radical cyclisation methodologies. A combination of EPR and kinetic studies has been used to assess the antioxidant characteristics of selenotocopherol. A two-phase lipid peroxidation model revealed that the selenotocopherol is not catalytically regenerable. The same model has been used to assess the cooperativity of mixtures of tellurides with α-tocopherol and an aqueous thiol. It was seen that combinations of α-tocopherol with tellurides incorporating phenols displayed synergistic properties, and the mechanistic implications of this are discussed. DSC measurements have been used to assess the antioxidant activity of tellurides together with coantioxidants in melts of polypropylene. The tellurides display excellent activity together with thiol or a sterically hindered phenol antioxidant. In chemiluminescence studies performed at lower temperatures, the telluride mixtures still outperform commercial blends, but to a lesser extent. In a synthetic oil a telluride has demonstrated promising antioxidant properties together with a thiol or phenolic antioxidant. However, under more realistic test conditions the telluride acts instead as a prooxidant. Some tellurides have been evaluated as antioxidants in paper. Water-soluble tellurides appear to function better than lipophilic tellurides, but neither is comparable in activity to α-tocopherol.