Neste trabalho, foram realizados estudos sobre a modelagem e simulação do núcleo morto em partículas catalíticas contendo enzimas imobilizadas. Tais estudos envolveram a resolução de problemas de valor de contorno gerados pela modelagem dos fenômenos de difusão-reação no interior da partícula. Os principais parâmetros que determinam a ocorrência do núcleo morto foram investigados e os perfis de concentração de substrato e produto, bem como a posição do núcleo morto para a cinética de Michaelis-Menten e outras, foram calculados para catalisadores com geometrias clássicas de placa plana infinita, cilindro infinito e esfera. Para este fim, os seguintes métodos numéricos foram utilizados: shooting, colocação ortogonal global e colocação ortogonal em elementos finitos. Entre os métodos avaliados, o método da colocação ortogonal em elementos finitos foi o único capaz de representar os perfis de concentração de substrato e de produto, e os valores do fator de efetividade obtidos com as soluções analíticas para cinéticas de ordem zero e de primeira ordem, as quais foram usadas como referência. Assim, este método foi empregado para resolver os problemas de valor de contorno envolvendo as cinéticas de Michaelis-Menten e aquelas com inibição competitiva, não competitiva e acompetitiva por produto, e com inibição acompetitiva por substrato, sendo os resultados obtidos consistentes para todas as cinéticas analisadas. A metodologia proposta foi então usada para estudos de projeto e operação de reatores enzimáticos contínuos de mistura perfeita e de fluxo pistonado, sendo que os resultados obtidos foram coerentes. Assim, a metodologia apresentada neste trabalho pode ser avaliada em condições reais de projeto e operação de reatores enzimáticos heterogêneos contínuos. / This work dealt with studies on the modeling and simulation of the dead core in porous catalytic particles containing immobilized enzymes. Such studies involved the solution of boundaryvalue problems generated by the modeling of the diffusion-reaction phenomena inside the particle. The main parameters that determine the occurrence of dead core were investigated and the concentration profiles of substrate and product, as well as the position of the dead core for Michaelis-Menten\'s and other kinetics in catalysts with classical geometries of infinite slab, infinite cylinder and sphere were calculated. For this purpose, the following numerical methods were used: shooting, global-orthogonal-collocation and orthogonal-collocation in finite elements. Among these methods, only the orthogonal-collocation in finite elements simulated all substrate and product-concentration profiles and the effectiveness-factor values obtained with the analytical solutions for zero and first-order kinetics, which were used as reference. Therefore, this method was employed to solve the problems including the Michaelis-Menten kinetics, the competitive-, non-competitive- and acompetitive-product-inhibition kinetics, and the acompetitive-substrate-inhibition kinetics. The results obtained for all kinetics analyzed were consistent. Thus, the proposed methodology was used for studies on the design and operation of both continuous-stirred-tank and plug-flow reactors, and the results obtained were coherent. Thus, the methodology presented in this work can be evaluated under real conditions of design and operation of continuous heterogeneous enzymatic reactors.

Organophosphates and carbamates are potent inhibitors of the neurotransmitter acetylcholinesterase. This inhibition results in the blocking of nerve signal transference into the post synaptic neuron leading to loss of muscle action and death. Because of the universal mechanisms of signal transduction in animals, these inhibitors have been widely used as agricultural pesticides as well as chemical warfare agents (nerve agents). Health issues associated with pesticide usage result from the fact that both the pesticides and their breakdown products often end up in water and food sources as well as in the soil. As a result, there has been an increase in the number of studies aimed at the detection of these pesticides in the environment. One popular research area is enzyme based biosensor construction. Some important criteria for consideration during the construction of biosensors are the importance of a suitable solid support as well as the enzyme immobilisation method. Recently, there has been increased interest in using nano-scale material e.g. using nanoparticles as enzyme support material. This is largely due to their advantages such as large surface area to volume ratio as well as reduced mass transfer resistance. Electrospinning is a straight forward and cost effective method for producing nanofibres from any soluble polymer(s). The applications of electrospun nanofibres have been reported in clinical studies, biofuel production as well as bioremediation. In this study two polymers were selected: nylon for its mechanical stability and chitosan for its biocompatibility and hydrophilicity, for the fabrication of electrospun nanofibres which would function as immobilisation support material for acetylcholinesterase. The first objective of this study was to electrospin nanofibres from a nylon-6 and chitosan blend solution. A binary solvent system consisting of formic acid and acetic acid (50:50) successfully dissolved and blended the polymers which were subsequently electrospun. Scanning electron microscopy characterisation of the nanofibres showed that (i) a nylon-6: chitosan ratio of 16%: 3% resulted in the formation of bead free nanofibres and (ii) the fibres were collected in non-woven mats characterised by different size nanofibres with average diameters of 250 nm for the main fibres and 40 nm for the smaller nanofibres. Fourier transform infra-red (FT-IR) analysis of the nanofibres indicated that a new product had been formed during the blending of the two polymers. The second aim of the study was to carry out a facile immobilisation of electric eel acetylcholinesterase via glutaraldehyde (GA) cross-linking. Glutaraldehyde solution 5% (v/v) resulted in the immobilisation of 0.334 mg/cm² of acetylcholinesterase onto the nanofibres. The immobilisation procedure was optimised with reference to acetylcholinestease and crosslinker concentrations, incubation time and the cross-linking method. A comparative investigation into the optimum pH and temperature conditions, pH and thermal stabilities, substrate and inhibition kinetics was then carried out on free and immobilised acetylcholinesterase. The final objective of this study was to determine the storage stabilities of the immobilised and free enzymes as well as the reusability characteristics of the immobilised acetylcholinesterase. Several conclusions were drawn from this study. Acetylcholinesterase was successfully immobilised onto the surface of nylon-6:chitosan nanofibres with retention of its activity. There was a shift in the pH optimum of the immobilised acetylcholineseterase by 0.5 units towards a neutral pH. Although both free and immobilised acetylcholinesterase exhibited the same optimum temperature, immobilised acetylcholinesterase showed enhanced thermal stability. In terms of pH stability, immobilised acetylcholinesterase showed greater stability at acidic pH whilst free acetylcholinesterase was more stable under alkaline pH conditions. Relative to free acetylcholinesterase, the immobilised enzyme showed considerable storage stability retaining ~50% of its activity when stored for 49 days at 4°C. Immobilised acetylcholinesterase also retained > 20% of its initial activity after 9 consecutive reuse cycles. When exposed to fixed concentrations of carbofuran or demeton-S-methyl sulfone, immobilised acetylcholinesterase showed similar inhibition characteristics to that of the free enzyme. The decrease in enzyme activity observed after immobilisation to the nanofibres may have been due to several reasons which include some enzyme molecules being immobilised in structural conformations which reduced substrate access to the catalytic site, participation of the catalytic residues in immobilisation and enzyme denaturation due to the reaction conditions used for acetylcholinesterase immobilisation. Similar observations have been widely reported in literature and this is one of the major drawbacks of enzyme immobilisation. In conclusion, nylon-6:chitosan electrospun nanofibres were shown to be suitable supports for facile acetylcholinesterase immobilisation and the immobilised enzyme has potential for use in pesticide detection. Future recommendations for this study include a comparative study of the GA cross-linking method for AChE immobilisation which will lead to more intensely bound enzyme molecules to prevent non-specific binding. An investigation into the effect of inhibitors on stored immobilised AChE, as well as reactivation and reuse studies, may also be useful for determining the cost-effectiveness of reusing immobilised AChE for pesticide detection in environmental water samples. Several models have been designed for the determination of the kinetic parameters for immobilised enzymes. These take into account the mass transfer resistance as well as the overall charge of the immobilisation matrix. The use of these models to analyse experimental data will give a clear understanding of the effects of immobilisation on enzyme activity

Made available in DSpace on 2014-10-09T12:33:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:58Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientadores: Maria Helena Andrade Santana, Heizir Ferreira de Castro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-27T20:07:32Z (GMT). No. of bitstreams: 1 Soares_CleideMaraFaria_M.pdf: 5966176 bytes, checksum: 181a14205ef4b15d71734d115dd39efe (MD5) Previous issue date: 2000 / Resumo: A metodologia de preparação do biocatalisador pode influenciar no processo catalítico. De acordo com estudos anteriores a lipase de Candida rugosa pode ser imobilizada com presença de alta atividade em sílica de porosidade controlada (SPC) ativada com glutaraldeído. Neste trabalho, foram desenvolvidas estratégias para otimizar a estabilidade operacional desta preparação de lipase imobilizada. Para atingir este propósito, foram testados diferentes tipos de agentes estabilizantes com a finalidade de proteger a enzima de efeitos de agregação ou desnaturação que ocorrem devido à presença dos silanos usados durante a formação da matriz de sílica. Os aditivos usados como estabilizantes foram as proteínas (albumina e lecitina) e os polímeros orgânicos (P-ciclodextrina e polietilenoglicol) e seus efeitos foram comparados ao controle (lipase imobilizada sem aditivo). A metodologia de planejamento experimental foi utilizada para selecionar o aditivo que fornecesse maior rendimento de imobilização. Foram realizados três planejamentos fatoriais completos 22, com repetição no ponto central para avaliar a variável resposta, em função do tipo de aditivo e concentração de enzima. Entre todos os aditivos testados, rendimentos mais elevados foram obtidos quando PEG-1500 foi utilizado como agente estabilizante. De acordo com os resultados estatísticos, um novo planejamento fatorial completo 22, com repetição no ponto central foi realizado, para avaliar o rendimento de imobilização em função da concentração de PEG-1500 e lipase. Utilizandose da metodologia de superficie resposta, obteve-se o seguinte modelo matemático para o rendimento de imobilização: Y = 50,91+4,70X1 - 9,89X2 + 4,04 XI X2 onde X I e X2 correspondem aos valores codificados para as variáveis concentração de aditivo e enzima, respectivamente. A estabilidade operacional das preparações de lipase imobilizada na presença de PEG-1500 foi determinada na síntese de butirato de butila em regime de bateladas consecutivas. Adotando a estratégia proposta neste trabalho, o tempo de meia vida da lipase imobilizada em SPC foi aumentado em 13 vezes, quando comparado com o tempo de meiavida do controle (lipase imobilizada em SPC sem aditivo) / Abstract: The method for preparing the biocatalyst can influence the catalytic processo In agreement with previous studies Candida rugosa lipase can be immobilized with high activity retention on silanized controlled pore silica (CPS) activated with glutaraldehyde. This work aimed at improving the performance of the immobilized form in long-term operation. Five additives were tested in the immobilization step in order to select the most activity derivative for esterification reactions. This strategy is suggested to protect the enzyme from aggregation effects or denaturation that occur due to the presence of silane precursors used in the formation of the silica matrix. Proteins (albumin and lechitin) and polymers (B-cyclodextrin and polyethyleneglycol) were added during the immobilization procedure and their effects are reported and compared with the behavior of the immobilized biocatalyst in the absence of additive. The methodology of experimental design was used to select the most efficient additive considering the coupling yield as a response variable. Three 22 full factorial design with repetitions at the center point were employed to evaluate the immobilization yield as a function of additive type and lipase loading. The best stabilizing effect was found when small amounts of PEG-1500 and lipase were added simultaneously to the lipase onto support. According to statistic results, further 22 full factorial design with 2 repetitions at the center point were employed to evaluate the immobilization yield as a function of PEG and lipase concentrations. A response surface methodology permitted to obtain the following mathematical model for immobilization yield: Y = 50.91+4.70X1 - 9.89X2 + 4.04 Xl X2 where: Xl and X2 are the codified values for additive PEG-1.500 and enzyme concentrations, respectively. This immobilized system was used to perform esterification reactions under repeated batch cycles (for the synthesis of butyl butyrate as a model). The half-life of the lipase immobilized on CPS in the presence of PEG-1500 was found to increase 13 times when compared with the control (immobilized lipase on CPS without additive) / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Made available in DSpace on 2014-10-09T12:33:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:58Z (GMT). No. of bitstreams: 0 / A nanociência e a nanotecnologia vêm abrindo inúmeros desenvolvimentos de dispositivos e sistemas em escala nanométrica, com novas organizações moleculares, propriedades e funções distintas. Nesse contexto, as nanopartículas magnéticas poliméricas são compósitos formados por materiais magnéticos com tamanhos de partículas entre 1 e 100 nm combinados com polímeros funcionais. São materiais bem conhecidos e têm sido amplamente estudados devido às suas aplicações em diversas áreas tecnológicas. Nas áreas biológica e médica, as aplicações incluem separação e imobilização de enzimas e proteínas, melhoria nas técnicas de imagem de ressonância magnética para diagnóstico e sistemas de liberação controlada de fármacos. Neste trabalho, proteínas foram imobilizadas na superfície de um biopolímero combinado com partículas superparamagnéticas de magnetita para formar o compósito magnético. Utilizou-se o biopolímero quitosana, reticulada e funcionalizada com glutaraldeído, aplicável em ensaios biológicos. Obtiveram-se 3 tipos de compósitos magnéticos, os quais foram nomeados QM1Glu, QM2NaGlu e QM3Glu. Foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura, magnetometria de amostra vibrante, calorimetria exploratória diferencial, termogravimetria e espectroscopia por infravermelho. Foram avaliados quanto à imobilização das proteínas albumina de soro bovino (SAB), colágeno e tripsina. A imobilização das proteínas no biopolímero ocorreu em 30 min de incubação. O compósito magnético de quitosana não funcionalizada (QM3) também foi avaliado. Para a tripsina verificou-se que QM3 apresentou maior potencial de imobilização do que QM3Glu. Após 30 dias, QM3-Trip e QM3Glu-Trip ainda apresentavam a tripsina ativada. Foram demonstradas a atividade e a cinética enzimática da QM3Glu-trip com o substrato BApNA. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Cette étude vise à produire deux enzymes amylolytiques (α-amylase et pullulanase) thermostables par des levures contaminant le blé récolté dans des zones semi arides et arides (Biskra - Sahara, Sud Algérien) et capables d’hydrolyser à la fois les liaisons α-1-4 et α-1-6 de polysaccharides comme l’amidon et le pullulane, molécules d’intérêt industriel. Après isolement et caractérisation de colonies levuriennes, la méthode de plate-test-agar permet d’isoler des souches amylolytiques et de montrer que la souche L7 est la plus performante dans la production enzymatique parmi une douzaine de souches de levures productrices d’α-amylase et de pullulanase thermostables. L’identification des souches, basée sur les caractères morphologiques, les tests biochimiques et la biologie moléculaire a permis de répartir la population comme suit : 50% Clavispora lusitaniae (forme anamorph Candida lusitaniae), 25%, Pichia guilliermondii, 8% Pichia carribbicca, 8% Meyerozyma guilliermondii et 8% Rhodotorula rubra. Par sa richesse en amidon, le biotope du blé est favorable à la survie des levures amylolytiques. La majorité de ces souches dont la souche L7 est productrice de pseudo ou vrai mycélium et est tolérante à certains paramètres comme la température, la salinité, les stress osmotique et éthanolique. La souche de levure L7, Clavispora lusitaniae ABS7, semble être la plus performante dans la production d’enzymes thermostables. Son identification moléculaire a montré deux bandes avec l’endonucléase HAE III alors que les autres souches de la même espèce de Clavispora lusitaniae (L5, L9, L10, L11 et L12) présentent une seule bande. En conditions optimales (agitation 136,56 rpm, température 54,14°C, amidon 2,66g/l, extrait de levure 0,365g/l, sels 8, 75ml/l et oligo-éléments 4,3ml/l en erlenmeyers de 250 ml), la production maximale atteint les valeurs suivantes : 13456,36±300 UI pour l’ α-amylase et 12611, 6±154 UI pour la pullulanase. Ces performances sont en accord étroit avec la prédiction du modèle statistique évaluée à 13231UI pour l’α-amylase et 12825,5 UI pour la pullulanase. La production optimisée a pratiquement doublé par rapport à la production avant l’optimisation (6639,16 UI pour l’α-amylase et 6308,5 UI pour la pullulanase). En conditions optimales et en fermenteur de 2 L, la production maximale pour les deux enzymes de la levure Clavispora lusitaniaeABS7 est obtenue au bout de 28 h avec un optimum de croissance obtenu à 40 heures. La production des deux enzymes n’est donc pas associée à la croissance. La production maximale des deux enzymes s’effectue à pH 8. pic protéique. L’élution sur DEAE-cellulose confirme la présence des deux activités dans la même fraction. Les deux enzymes sont donc présentes sur la même molécule. L’α-amylase et la pullulanase sont purifiées avec un taux de purification de 50,5 et 44,6 respectivement et des rendements respectifs de 23,9% et 21,1%. L’extrait purifié montre une seule bande sur le gel de SDS-PAGE avec un poids moléculaire estimé à 75KDa et une activité amylolytique contenant à la fois les activités α-amylasique (indépendante de Ca2+) et pullulanasique (une métalloenzyme à calcium). La souche de la levure Clavispora lusitaniae ABS7 possède donc une enzyme amylolytique avec deux sites actifs. La CCM révèle une enzyme qui hydrolyse l’amidon en maltose et glucose et le pullulane en maltotriose, maltose et glucose, ce qui montre que l’enzyme est saccharifiante et correspond à une pullulanase de type II (amylopullulase). L’optimisation de l’immobilisation de l’enzyme a permis l’amélioration de l’activité: α-amylasique à 4907,75 UI (rendement 72,3 %) et celle de la pullulanase à 4491,83 UI (rendement 70,1%) avec un pH optimum de 8,5. Il ressort de notre étude que l’amylopullulanase type II libre de Clavispora lusitaniae ABS7 est thermostable puisqu’elle résiste à un traitement thermique de 75°C pendant 3 heures d’incubation et conserve 88% de son activité initiale. / This study aims to produce two amylolytic enzymes (α-amylase and pullulanase) by thermostable wheat contaminant yeast harvested in semi arid and arid zones (Biskra, Sahara, Algeria SUD) and capable of hydrolyzing both the α links 1-4 and 1-6 of polysaccharides such as starch and pullulan, molecules of industrial interest. After isolation and characterization of levuriennes colonies, the test method of agar-plate allows to isolate amylolytic strains and show, that the L7 strain is the most effective, in the enzymatic production of the 12 yeast strains producing α-amylase and pullulanase the thermostable. The identification of strains, based on morphological, biochemical tests and molecular biology has helped spread the population as follows: 50% Clavispora lusitaniae (anamorph form Candida lusitaniae), 25%, Pichia guilliermondii, 8% carribbicca Pichia, 8% Meyerozyma guilliermondii and 8% Rhodotorula rubra. By its high starch, the wheat biotope is favorable to the survival of amylolytic yeasts. Most of these strains, including the strain L7, is producer, pseudo or true mycelium and is tolerant to certain parameters such as temperature, salinity, osmotic stress and ethanolic stress. The yeast strain Clavispora lusitaniae ABS7 (L7) seems to be the most efficient in the production of thermostable enzymes. Its molecular identification showed two bands with the endonuclease HAE III while other strains of the same species Clavispora lusitaniae (L5, L9, L10, L11 and L12) have a single band. In optimal conditions (agitation 136.56 rpm, temperature 54.14 ° C, starch 2,66g / l, yeast extract 0,365g / l, salts 8 75ml / l and trace elements 4,3ml / liter Erlenmeyer flasks into 250 ml), the maximum production reached: 13456.36 ± 300 IU for the α-amylase and 12611, 6 ± 154 IU for pullulanase. This performance is in close agreement with the prediction of the statistical model 13231UI evaluated for α-amylase and 12825.5 IU for pullulanase. The optimized production almost doubled compared to production before optimization (6639.16 IU for the α-amylase and pullulanase for 6308.5 IU). In optimal conditions, and 2 L fermenter, the maximum production for the two enzymes of Clavispora lusitaniae ABS7 obtained after 28 hours, with an optimum of growth obtained at 40 hours. The production of both enzymes is thus not associated with growth. The maximum production of both enzymes is obtained at pH 8. The kinetics are characterized by an increase in carbohydrate and a substance spooning the wall of the fermenter, probably an exo-polysaccharide. The chromatographic profile on Sephacryl S200 reveals two α-amylase and pullulanase activities eluted along with the protein peak. Elution DEAE cellulose confirms the presence of both activities in the same fraction. Both enzymes are present on the same molecule. The α-amylase and pullulanase were purified with a purification rate of 50.45 and 44.59 respectively and respective yields of 23.88% and 21.11%. The purified enzyme showed a single band on SDS-PAGE gel with a molecular weight estimated at 75 KDa and an amylolytic activity containing both the α-amylase activities (independent of Ca2+) and pullulanase (a calcium metalloenzyme). The strain of the yeast Clavispora lusitaniae ABS7 therefore has an amylolytic enzyme with two active sites. TLC reveals an enzyme which hydrolyzes starch into maltose and glucose and pullulan into maltotriose, maltose and glucose, which shows that the saccharifying enzyme, and corresponds to a pullulanase type II (amylopullulase). The optimization of the immobilization of the enzyme enabled the improvement of the activity: α-amylase to 4907.75 IU (yield 72.3%) and pullulanase to 4491.83 IU (yield 70, 1%) with a pH optimum of 8.5. It appears from our study that amylopullulanase type II free is thermostable to heat treatment of 75 ° C for 3 hours of incubation, and retains 88% of its original activity.

Se presenta un modelo matemático para el diseño y simulación de un reactor de lecho fijo con enzimas inmovilizadas en partículas esféricas porosas. La ecuación de diseño del reactor se ha resuelto para el caso de un sistema enzimático, con limitaciones difusionales internas, que obedece a una cinética de Michaelis-Menten reversible.La validez del modelo se ha comprobado con el sistema enzimático naringina/naringinasa, aplicable al proceso de desamargado de zumos cítricos. / A mathematical model for design and simulation of a fixed bed reactor with immobilized enzymes in spherical particles is presented. The reactor design equation is solved for an enzymatic system taking into account internal diffusional limitations. Moreover, the enzyme obeys a reversible Michaelis-Menten kinetic. The validity of the model is checked by using the enzymatic system naringine/naringinase, which is used for fruit juice debbitering processes.

Les biocapteurs sont des moyens d’analyse en plein essor à la fois rapides, sélectifs et peu coûteux applicables à des domaines extrêmement variés (environnement, santé, agroalimentaire,…). Dans ce type d’outil, un élément sensible de nature biologique (anticorps, enzyme, microorganisme, ADN…) doté d’un pouvoir de reconnaissance pour un analyte ou un groupe d’analytes est associé à un transducteur pouvant être de type électrochimique, optique ou thermique.Dans ce travail, nous nous sommes intéressés au développement de trois biocapteurs pour la détection de substances biologiquement actives. Le premier permet la détermination simultanée de l’adénosine triphosphate (ATP) et du glucose par ampérométrie, le deuxième celle de la créatine kinase, et le troisième est un biocapteur conductimétique pour la quantification de l’ATP. Dans les deux premiers biocapteurs, deux enzymes (l’hexokinase et la glucose oxydase) sont immobilisées à la surface de microélectrodes constituées d’un disque de platine. Le troisième biocapteur est basé sur l’immobilisation de l’hexokinase sur des microélectrodes interdigitées en or. L’immobilisation est réalisée dans tous les cas par co-réticulation des enzymes en présence d’albumine de sérum bovin à l’aide de glutaraldehyde. Les caractéristiques analytiques des biocapteurs ont été déterminées et différentes procédures ont été développées pour l’analyse d’échantillons réels. Les biocapteurs ont pu être appliqués avec succès à la quantification de l’ATP, du glucose et de la créatine kinase dans des préparations pharmaceutiques et du sérum sanguin / Biosensors are rapid, selective and inexpensive devices that combine a biological recognition element, the so-called bioreceptor (e.g. enzymes, antibodies, DNA or microorganisms) to a physical transducer (e.g. electrochemical, optical, thermal or piezoelectrical). They can be used to detect one specific analyte or one family of analytes for a wide range of applications (e.g. environment, food, health). In this work, the detection of biologically active substances was targeted. A biosensor system for simultaneous determination of adenosine triphosphate (ATP) and glucose, a biosensor for creatine kinase analysis, and a novel conductometric biosensor for ATP determination were developed. In the first two biosensors, two enzymes (hexokinase and glucose oxidase) were immobilized at the surface of platinum disc microelectrodes for amperometric detection. The third biosensor was based on hexokinase immobilized onto gold interdigitated microelectrodes for conductometric detection. In all cases, the enzymes were co-immobilized with bovine serum albumin by cross-linking using glutaraldehyde. Analytical characteristics of the biosensors were determined and different procedures were developed for real samples analysis. The biosensors could be successfully applied to the determination of ATP, glucose, and creatine kinase in pharmaceutical samples and blood serum

Réalisé en codirection avec Karen C. Waldron et Dominic Rochefort. / L’objectif principal de ce projet de recherche est d’étudier l’efficacité de la microencapsulation, technique d’immobilisation d’enzymes utilisée pour la réalisation des nouveaux biocapteurs électrochimiques. Généralement, l’analyte d’intérêt produit ou consomme des électrons, et la réponse électrochimique est mesurée, afin d’identifier ou quantifier l’analyte. Dans le développement d’un biocapteur, il est désirable de quantifier la conversion du substrat (analyte) et/ou la formation de produit de réaction enzymatique. Les similarités structurales entre le substrat et le produit de réaction dans les réactions redox demandent que la technique utilisée pour les identifier soit très sélective. Le haut pouvoir de résolution de l’électrophorèse capillaire (EC) pour des séparations rapides de produits similaires en fait une méthode de choix, spécialement quand le substrat et le produit peuvent être suivis pendant et après la réaction catalysée par l’enzyme immobilisée. Un choix judicieux du substrat, compte tenu de son comportement en EC peut fournir des informations autant sur l’activité de l’enzyme que sur l’efficacité de la microencapsulation. Pour cette raison, nous avons choisi le substrat o-phenylènediamine qui est oxydé par la laccase, pour former le produit 2,3-diaminophenazine, tout en réduisant l’oxygène en eau. Pour commencer, nous avons préparé les microcapsules et évalué l’impact de la microencapsulation sur le comportement de l’enzyme. Ensuite, nous avons développé une méthode de séparation en EC afin de quantifier la conversion de l’OPD en DAP par la laccase libre. La même méthode d’analyse a été utilisée pour caractériser la laccase immobilisée dans les microcapsules. Par la suite, afin de suivre la réaction enzymatique, un microréacteur à base d’enzyme microencapsulée a été couplé hors ligne au système d’EC. Finalement, nous avons essayé l’implémentation du système en ligne et les résultats préliminaires seront présentés. / The principal objective of this research project is to study the efficiency of microencapsulation, technique used for enzyme immobilization in order to create new types of electrochemical biosensors. Generally, the target analyte involved either produces or consumes electrons and the electrochemical response is measured to identify or quantify the analyte. In the development of a biosensor, it is desirable to quantify the conversion of substrate (analyte) and/or the formation of product of the enzymatic reaction. The structural similarity between substrate and product in redox reactions means that the technique used to determine these species must be very selective. The high resolving power of capillary electrophoresis (CE) for rapidly separating similar compounds is thus an attractive method, particularly if substrate and product can both be monitored during or following the reaction catalyzed by microencapsulated enzyme. A judicious choice of substrate with respect to its behaviour in CE separations can help provide information on enzyme activity as well as microencapsulation efficiency. To achieve this, we chose the substrate o-phenylenediamine (OPD), which is oxidized by laccase to form the product 2,3-diaminophenazine (DAP) concomitant with the reduction of molecular oxygen to water. We firstly prepared the microcapsules and evaluate the impact of microencapsulation on the behaviour of the enzyme. After that, we developed a CE based separation method to quantify the conversion of OPD to DAP by free laccase. We also used the CE method to characterize laccase immobilized in microcapsules. Subsequent, the microencapsulated laccase was packed into a microreactor format permitting its off-line coupling with CE as a means to follow the enzymatic reaction. Finally, we tried to implement the on-line system and the preliminaries results are presented.

L’objectif principal de ce projet de recherche est d’étudier l’efficacité de la microencapsulation, technique d’immobilisation d’enzymes utilisée pour la réalisation des nouveaux biocapteurs électrochimiques. Généralement, l’analyte d’intérêt produit ou consomme des électrons, et la réponse électrochimique est mesurée, afin d’identifier ou quantifier l’analyte. Dans le développement d’un biocapteur, il est désirable de quantifier la conversion du substrat (analyte) et/ou la formation de produit de réaction enzymatique. Les similarités structurales entre le substrat et le produit de réaction dans les réactions redox demandent que la technique utilisée pour les identifier soit très sélective. Le haut pouvoir de résolution de l’électrophorèse capillaire (EC) pour des séparations rapides de produits similaires en fait une méthode de choix, spécialement quand le substrat et le produit peuvent être suivis pendant et après la réaction catalysée par l’enzyme immobilisée. Un choix judicieux du substrat, compte tenu de son comportement en EC peut fournir des informations autant sur l’activité de l’enzyme que sur l’efficacité de la microencapsulation. Pour cette raison, nous avons choisi le substrat o-phenylènediamine qui est oxydé par la laccase, pour former le produit 2,3-diaminophenazine, tout en réduisant l’oxygène en eau. Pour commencer, nous avons préparé les microcapsules et évalué l’impact de la microencapsulation sur le comportement de l’enzyme. Ensuite, nous avons développé une méthode de séparation en EC afin de quantifier la conversion de l’OPD en DAP par la laccase libre. La même méthode d’analyse a été utilisée pour caractériser la laccase immobilisée dans les microcapsules. Par la suite, afin de suivre la réaction enzymatique, un microréacteur à base d’enzyme microencapsulée a été couplé hors ligne au système d’EC. Finalement, nous avons essayé l’implémentation du système en ligne et les résultats préliminaires seront présentés. / The principal objective of this research project is to study the efficiency of microencapsulation, technique used for enzyme immobilization in order to create new types of electrochemical biosensors. Generally, the target analyte involved either produces or consumes electrons and the electrochemical response is measured to identify or quantify the analyte. In the development of a biosensor, it is desirable to quantify the conversion of substrate (analyte) and/or the formation of product of the enzymatic reaction. The structural similarity between substrate and product in redox reactions means that the technique used to determine these species must be very selective. The high resolving power of capillary electrophoresis (CE) for rapidly separating similar compounds is thus an attractive method, particularly if substrate and product can both be monitored during or following the reaction catalyzed by microencapsulated enzyme. A judicious choice of substrate with respect to its behaviour in CE separations can help provide information on enzyme activity as well as microencapsulation efficiency. To achieve this, we chose the substrate o-phenylenediamine (OPD), which is oxidized by laccase to form the product 2,3-diaminophenazine (DAP) concomitant with the reduction of molecular oxygen to water. We firstly prepared the microcapsules and evaluate the impact of microencapsulation on the behaviour of the enzyme. After that, we developed a CE based separation method to quantify the conversion of OPD to DAP by free laccase. We also used the CE method to characterize laccase immobilized in microcapsules. Subsequent, the microencapsulated laccase was packed into a microreactor format permitting its off-line coupling with CE as a means to follow the enzymatic reaction. Finally, we tried to implement the on-line system and the preliminaries results are presented. / Réalisé en codirection avec Karen C. Waldron et Dominic Rochefort.