Este trabalho tem como principal objetivo comparar as respostas de biossensores amperomé-tricos preparados a partir do uso de uma enzima, a tirosinase (polifenoloxidase, PFO), quando nas formas purificada e adquirida comercialmente e de extrato bruto enzimático do fruto do abacate (Persea Americana). As soluções de PFO apresentaram valores de atividades enzimá-ticas de 479 unidades de enzimas ativas por mililitro (UA mL-1) (purificada) e 259 UA mL-1 (extrato bruto). A enzima nas duas formas (pura e como extrato bruto) foi imobilizada quimi-camente em substratos de Au modificados com monocamadas automontadas (self-assembly monolayers, SAMs) de ácido mercaptopropiônico (MPA) pela técnica de impressão por mi-crocontato (CP). Os biossensores foram preparados sobre substratos de Au modificados por CP com um molde elastomérico de polidimetilsiloxano (PDMS), cujas trilhas paralelas de 100 m foram produzidas pela cura polimérica sobre um molde mestre de GaAs. A réplica de PDMS se mostrou fiel em relação ao molde mestre nos picos e vales, mas apresentou defeitos na borda dos moldes. Com o objetivo de otimizar o funcionamento dos biossensores, eles fo-ram caracterizados pelas técnicas de voltametria cíclica e cronoamperometria com um sistema de análise de injeção em fluxo (FIA) em meio de catecol a diferentes concentrações. Os po-tenciais de oxidação do catecol nos eletrodos de Au modificados foram observados em 418 e 365 mV, em pHs ótimos de funcionamento de 7,0 e 7,2, e com limites de detecção de 6,65 nmol L-1 e 4,65 nmol L-1 para os biossensores com a enzima purificada e com o extrato bruto, respectivamente. A saturação dos sensores teve início a uma concentração de catecol de 0,02 mol L-1. Com estes resultados, mostramos que é possível o preparo de biosensores com um baixo custo, eficientes e miniaturizadas a partir do uso da PFO na forma extrato bruto do fruto do abacate para a detecção de compostos fenólicos, tal como catecol, abrindo assim a possibi-lidade de uso destes biossensores na análise e no monitoramento de pesticidas presentes no solo e na água. / The main objective of this master thesis is to compare the performance of amperometric biosensors prepared using the purified tirosinase (PPO) enzyme, (commercially acquired) and the PPO present in the enzymatic crude extract from the avocado fruit (Persea Americana). The PPO solutions had 479 units of active enzyme per milliliter (UA mL-1) (purified) and 259 UA mL-1 (crude extract). Both forms of the enzyme (purified and crude extract) were chemically immobilized on gold substrates patterned with 3-mercaptopropionic acid (MPA) self assembled monolayers (SAMs), using the microcontact printing (CP) technique. The biosensors were prepared on gold subtracts patterned using CP with a polydimethylsiloxane (PDMS) elastomeric mold, that was shaped in the form as tracks using a gallium arsenate master mold. The PDMS mold was quite similar to the master mold in its peaks and valleys, but defects were found on the edges. In order to optimize the parameters of the biosensors , they were characterized using cyclic voltammetry and chronoamperometry techniques in a FIA system by cathecol injections at different concentrations. The oxidation potentials for the cathecol analysis using the patterned biosensors were observed at 418 and 365 mV, the optimum pH were 7,0 and 7,0, with detection limits of 6,65 nmol L-1 and 4,65 nmol L-1 for the purified enzyme and crude extract biosensors, respectively. The biosensors saturation point started at 0,02 mol L-1 of cathecol concentration. With this results, we demonstrate that it is possible to use miniaturized, efficient, low cost biosensors based on tyrosine from the avocado´s fruit crude extract to detect phenolic compounds, as the cathecol. This expands the possibility of using this biosensors in the analysis and monitoring pesticides in water and soil.

Inspired by Poirier¡¦s mechanism of self-assembled monolayers (SAMs) formation, we realized that observation of the change of molecular orientation relative to the surface using a suitable spectroscopic method might be able to reveal the self ¡V assemblied processes. We mimicked the SAMs formation under UHV conditions, the Reflection Absorption Infrared Spectroscopy (RAIRS) and Temperature-Programmed Desorption / Reaction Spectrometry (TPD/R) were utilized to understand the adsorption, self-assembling and thermal stability after vapor desorption of 1H, 1H, 2H, 2H-perfluorodecanethiol on Cu(111). At 100K, the adsorption of 1H, 1H, 2H, 2H-perfluorodecanethiol was entirely molecular. As the surface was annealed above 220K, the cleavage of the S ¡V H bonds occurred to afford chemisorbed thiolates. By comparisons of spectra to the SAMs / Au(111) and the bulk compound, forming of an orderly and densely packed monolayer on Cu(111) was inferred. Focusing on room temperature deposition experiments, We found that the increase in ratios of I£h(CF2 ¡ü chain) (bands in 1300cm-1 ~ 1400 cm-1) to I£h(CF2 ¡æ chain) (bands in 1100cm-1 ~ 1300 cm-1) as a function of exposure implicates a transition from that the lying ¡V down geometry to the more upright orientation relative to the surface as we anticipated, the phase transformation concomitant with the SAMs formation could be identified by RAIRS. By TPD/R measurements, the molecular desorption occurred at 220K and 290K, corresponding to the condensed multilayer and a physisorbed layer on top of the chemisorbed monolayer, respectively. Furthermore, the monolayer would undergo the S ¡V C bond dissociation to sender surface ¡V bound semifluorinated alkyl groups and sulfur atoms. The semifluorinated decene and decane were evolved above 360K as results of £] ¡V hydride elimination and hydrogen addition.

Este trabalho tem como principal objetivo comparar as respostas de biossensores amperomé-tricos preparados a partir do uso de uma enzima, a tirosinase (polifenoloxidase, PFO), quando nas formas purificada e adquirida comercialmente e de extrato bruto enzimático do fruto do abacate (Persea Americana). As soluções de PFO apresentaram valores de atividades enzimá-ticas de 479 unidades de enzimas ativas por mililitro (UA mL-1) (purificada) e 259 UA mL-1 (extrato bruto). A enzima nas duas formas (pura e como extrato bruto) foi imobilizada quimi-camente em substratos de Au modificados com monocamadas automontadas (self-assembly monolayers, SAMs) de ácido mercaptopropiônico (MPA) pela técnica de impressão por mi-crocontato (CP). Os biossensores foram preparados sobre substratos de Au modificados por CP com um molde elastomérico de polidimetilsiloxano (PDMS), cujas trilhas paralelas de 100 m foram produzidas pela cura polimérica sobre um molde mestre de GaAs. A réplica de PDMS se mostrou fiel em relação ao molde mestre nos picos e vales, mas apresentou defeitos na borda dos moldes. Com o objetivo de otimizar o funcionamento dos biossensores, eles fo-ram caracterizados pelas técnicas de voltametria cíclica e cronoamperometria com um sistema de análise de injeção em fluxo (FIA) em meio de catecol a diferentes concentrações. Os po-tenciais de oxidação do catecol nos eletrodos de Au modificados foram observados em 418 e 365 mV, em pHs ótimos de funcionamento de 7,0 e 7,2, e com limites de detecção de 6,65 nmol L-1 e 4,65 nmol L-1 para os biossensores com a enzima purificada e com o extrato bruto, respectivamente. A saturação dos sensores teve início a uma concentração de catecol de 0,02 mol L-1. Com estes resultados, mostramos que é possível o preparo de biosensores com um baixo custo, eficientes e miniaturizadas a partir do uso da PFO na forma extrato bruto do fruto do abacate para a detecção de compostos fenólicos, tal como catecol, abrindo assim a possibi-lidade de uso destes biossensores na análise e no monitoramento de pesticidas presentes no solo e na água. / The main objective of this master thesis is to compare the performance of amperometric biosensors prepared using the purified tirosinase (PPO) enzyme, (commercially acquired) and the PPO present in the enzymatic crude extract from the avocado fruit (Persea Americana). The PPO solutions had 479 units of active enzyme per milliliter (UA mL-1) (purified) and 259 UA mL-1 (crude extract). Both forms of the enzyme (purified and crude extract) were chemically immobilized on gold substrates patterned with 3-mercaptopropionic acid (MPA) self assembled monolayers (SAMs), using the microcontact printing (CP) technique. The biosensors were prepared on gold subtracts patterned using CP with a polydimethylsiloxane (PDMS) elastomeric mold, that was shaped in the form as tracks using a gallium arsenate master mold. The PDMS mold was quite similar to the master mold in its peaks and valleys, but defects were found on the edges. In order to optimize the parameters of the biosensors , they were characterized using cyclic voltammetry and chronoamperometry techniques in a FIA system by cathecol injections at different concentrations. The oxidation potentials for the cathecol analysis using the patterned biosensors were observed at 418 and 365 mV, the optimum pH were 7,0 and 7,0, with detection limits of 6,65 nmol L-1 and 4,65 nmol L-1 for the purified enzyme and crude extract biosensors, respectively. The biosensors saturation point started at 0,02 mol L-1 of cathecol concentration. With this results, we demonstrate that it is possible to use miniaturized, efficient, low cost biosensors based on tyrosine from the avocado´s fruit crude extract to detect phenolic compounds, as the cathecol. This expands the possibility of using this biosensors in the analysis and monitoring pesticides in water and soil.

The present work is dealing with the synthesis and characterization of mono- to trinuclear Cu(II)- and Ni(II)-containing bis(oxamato) and bis(oxamidato) complexes, respectively. It will be derived to which extent the spin density distribution of mononuclear complexes, determined by electron paramagnetic resonance studies experimentally and calculated by quantum mechanical calculations, can be regarded as a measure of the magnitude of magnetic superexchange interactions of corresponding trinuclear complexes. The usability of tailor-made trinuclear complexes for their deposition in form of thin film by spin-coating is described as well as the magneto-optical characterization of these thin films. It is shown, that the tailor-made functionalization of mono- to trinuclear bis(oxamidato) complexes with long alkyl chains is suited to allow these complexes to assembly in monolayers on, e.g., HOPG(0001) (highly-oriented pyrolytic graphite), whereas the functionalization of the alkyl chains with S atoms allows the generation of self-assembled monolayers on metallic gold. Furthermore it is shown, that the functionalization of mono- and trinuclear Cu(II)-containing bis(oxamato) complexes with ferrocenediyle fragments allows to modify the magnetic properties by making use of the oxidation process Fe(II)/Fe(III). / Die vorliegende Arbeit befasst sich mit der Darstellung und Charakterisierung ein- bis dreikerniger Cu(II)- bzw. Ni(II)-haltiger bis(oxamato) oder bis(oxamidato) Komplexe. Es wird abgeleitet, inwiefern die aus Elektronenenspinresonanz- Untersuchungen experimentell und die quantenmechanisch berechneten Spindichteverteilungen einkerniger Komplexe ein Maß für die Größe der magnetischen Superaustauschwechselwirkungen korrespondierender dreikerniger Komplexe darstellt. Die Eignung maßgeschneiderter dreikerniger Komplexe zu ihrer Überführung in dünne Filme im nm-Bereich mittels Rotationsbeschichtung auf Si/SiO2-Substraten wird beschrieben sowie die magneto-optische Charakterisierung dieser dünnen Filme. Es wird gezeigt, dass durch gezielte Funktionalisierung mit langkettigen Alkylresten ein- bis dreikernige Cu(II)-haltige bis(oxamidato) Komplexe geeignet sind, auf Substraten wie HOPG(0001) (hochorientiertes pyrolytisches Graphit) zu Monolagen zu assemblieren während die zielgerichtete Funktionalisierung der Alkylketten mit S-Atomen es ermöglicht selbst-assemblierte Monolagen auf metallischem Gold zu generieren. Zusätzlich wird beschrieben, dass durch die Funktionalisierung von ein- und dreikernigen Cu(II)-haltigen bis(oxamato) mit Ferrocendiylresten die magentischen Eigenschaften durch den Oxidationsprozess Fe(II)/Fe(III) gezielt modifiziert werden können.

The present work is dealing with the synthesis and characterization of mono- to trinuclear Cu(II)- and Ni(II)-containing bis(oxamato) and bis(oxamidato) complexes, respectively. It will be derived to which extent the spin density distribution of mononuclear complexes, determined by electron paramagnetic resonance studies experimentally and calculated by quantum mechanical calculations, can be regarded as a measure of the magnitude of magnetic superexchange interactions of corresponding trinuclear complexes. The usability of tailor-made trinuclear complexes for their deposition in form of thin film by spin-coating is described as well as the magneto-optical characterization of these thin films. It is shown, that the tailor-made functionalization of mono- to trinuclear bis(oxamidato) complexes with long alkyl chains is suited to allow these complexes to assembly in monolayers on, e.g., HOPG(0001) (highly-oriented pyrolytic graphite), whereas the functionalization of the alkyl chains with S atoms allows the generation of self-assembled monolayers on metallic gold. Furthermore it is shown, that the functionalization of mono- and trinuclear Cu(II)-containing bis(oxamato) complexes with ferrocenediyle fragments allows to modify the magnetic properties by making use of the oxidation process Fe(II)/Fe(III). / Die vorliegende Arbeit befasst sich mit der Darstellung und Charakterisierung ein- bis dreikerniger Cu(II)- bzw. Ni(II)-haltiger bis(oxamato) oder bis(oxamidato) Komplexe. Es wird abgeleitet, inwiefern die aus Elektronenenspinresonanz- Untersuchungen experimentell und die quantenmechanisch berechneten Spindichteverteilungen einkerniger Komplexe ein Maß für die Größe der magnetischen Superaustauschwechselwirkungen korrespondierender dreikerniger Komplexe darstellt. Die Eignung maßgeschneiderter dreikerniger Komplexe zu ihrer Überführung in dünne Filme im nm-Bereich mittels Rotationsbeschichtung auf Si/SiO2-Substraten wird beschrieben sowie die magneto-optische Charakterisierung dieser dünnen Filme. Es wird gezeigt, dass durch gezielte Funktionalisierung mit langkettigen Alkylresten ein- bis dreikernige Cu(II)-haltige bis(oxamidato) Komplexe geeignet sind, auf Substraten wie HOPG(0001) (hochorientiertes pyrolytisches Graphit) zu Monolagen zu assemblieren während die zielgerichtete Funktionalisierung der Alkylketten mit S-Atomen es ermöglicht selbst-assemblierte Monolagen auf metallischem Gold zu generieren. Zusätzlich wird beschrieben, dass durch die Funktionalisierung von ein- und dreikernigen Cu(II)-haltigen bis(oxamato) mit Ferrocendiylresten die magentischen Eigenschaften durch den Oxidationsprozess Fe(II)/Fe(III) gezielt modifiziert werden können.