Le tétrachloroéthène (PCE) et les éthènes chlorés qui lui sont apparentés ont été abondamment utilisés pour plusieurs applications en industrie dès le début du 20e siècle. Ils sont cependant comptés parmi les polluants les plus communs des sols et de l’eau et beaucoup d’efforts sont déployés afin de les éliminer. Nous croyons que la conversion des éthènes chlorés en éthènes par des microorganismes est une solution prometteuse. Le premier aspect du projet visait donc à établir les conditions pour lesquelles un consortium enrichi en Dehalococcoides ethenogenes permettrait la conversion complète de PCE en éthène. Les expériences réalisées nous ont permis de souligner le rôle de l’acide lactique ajouté aux cultures comme source de carbone et source indirecte d’électrons pour la déhalorespiration. Nous avons également pu établir l’effet de la concentration initiale de biomasse dans les cultures sur le profil de déhalogénation du PCE. Le deuxième aspect du projet visait à développer un protocole d’encapsulation du consortium dans une matrice polymérique afin de profiter des nombreux avantages potentiels de l’encapsulation. Nous avons testé trois montages d’encapsulation différents : atomisation avec jet d’air, atomisation avec vibrations ultrasoniques et « drop-wise ». Le dernier montage prévoyait l’encapsulation des cultures dans des billes d’alginate enrobées de chitosane gélifié par du lignosulfonate. C’est le seul montage qui nous a permis d’encapsuler le consortium de façon efficace sans effet significatifs négatifs sur son activité de déchlorination. Aussi, la comparaison des profils de déhalogénation du PCE de cellules encapsulées et cellules libres a montré une plus faible accumulation de TCE, 1,2-DCE et VC dans les échantillons de cellules encapsulée et, par conséquent, une conversion plus rapide et plus complète du PCE en éthène. Finalement, nous avons observé une tendance favorable à l’idée que les microorganismes encapsulés bénéficient d’un effet de protection contre de faibles concentrations d’oxygène. / Tetrachloroethylene (PCE) and other chlorinated ethenes have been used for industrial purposes since the beginnning of 20th century. However, they are now considered common pollutants of soil and water. A lot of efforts are directed toward elimination of these compounds and we believe degradation of these chlorinated ethenes by microorganisms is the best solution. The first step of this project was to establish a complete conversion of PCE to its non-toxic product ethylene using an enriched consortium of Dehalococcoides ethenogenes. Our results show the importance of lactic acid as a carbon source and indirect source of electrons in a reaction known as dehalorespiration. We have been able to establish the effect of initial biomass on the biodegradation profile of PCE. The second step of the project was to obtain a working protocol for encapsulation of the consortium in a polymeric matrix. Such immobilization procedure would then allows numerous possible advantages as shown in the literature. We tested three encapsulation setups: air atomization, ultrasonic atomization and drop-wise technique. In the last setup, we successfully encapsulated the bacterial consortium into particles made of an alginate core surrounded by a chitosan layer. Thus the drop-wise technique allowed encapsulation of the consortium without negative effects on its dechlorination activity. In addition, the dechlorination profiles of encapsulated cells showed a lower accumulation of chlorinated intermediates TCE, 1,2-DCE and VC which yield a more rapid and complete conversion of PCE to ethylene. Finally, our results support the idea that encapsulated microorganisms may benefit from a protective effect when oxygen is present in the medium.

Polyuronic acids are an important constituent of seaweed and plants, and therefore represent a significant part of global biomass, providing an abundant carbon source for both terrestrial and marine heterotrophic bacteria. Through the action of polysaccharide lyases, polyuronic acids are degraded into unsaturated monouronic acid units, which are fed into the Entner-Doudoroff pathway where they are converted into pyruvate and glyceraldehyde-3-phosphate. The first step of this pathway was thought to occur non- enzymatically. A highly conserved sequence, kdgF was found in alginate and pectin utilization loci in a diverse range of prokaryotes, in proximity to well established enzymes catalyzing steps downstream in the Entner-Doudoroff pathway and I hypothesized that KdgF was involved in the catalysis of the first step of this pathway. The kdgF genes from both Yersinia enterocolitica and a locally acquired Halomonas sp. were expressed in Escherichia coli and their activity was examined using unsaturated galacturonic acid depletion activity assays. To gain perspective on the general structure of KdgF, x-ray crystallography was used to obtain a crystal structure of both HaKdgF and YeKdgF. These crystal structures provided insight into the molecular details of catalysis by the KdgF proteins, including their putative catalytic residues and a coordinated metal binding site for substrate recognition. To elucidate amino acids that may be involved in binding and/or catalysis, mutants were created in HaKdgF, and lack of activity was observed in four mutants (Asp102A, Phe104A, Arg108A, and Gln55A). The research done in this study suggests that KdgF proteins use a metal binding site coordinated by three histidines and several additional residues to cause a change in monouronic acid, thereby, affecting the unsaturated double bond. This suggests that KdgF is involved in the first step in the Entner-Doudoroff pathway, which is the linearization of unsaturated monouronic acids. / Graduate

This thesis is focused on the development of a gene delivery system, especially for the purpose of DNA vaccination. DNA expression vectors have the potential to be useful therapeutics for a wide variety of applications. A carrier system was designed to realize the delivery of genes to cells and the promotion of controlled adequate expression in the target cells. The low gene delivery efficiency observed with systems composed of polyplexes is mainly due to low stability of polycation e.g polyethylenimine-DNA complexes and inability of most of the complexes to the reach nucleus after entering the cells. The encapsulation of polyethylenimine-DNA complexes inside the alginate microspheres was expected to provide protection from nuclease-based attack, thereby, increasing the stability of the complex and also to achieve controlled release of the complex at the target tissue. In this study, controlled release of complexes from alginate microspheres was studied with DNA staining. In Tris-HCl buffer, the release of PEI-DNA complexes were completed in 48 h, however in cell culture medium (DMEM) 18 % of complexes were released in 48 h because of presence of Ca+2 ions in DMEM. Also, in order to provide mucosal gene delivery for mucosal immunization polyethylene glycol (PEG) was introduced into the composition of microspheres and the two systems were compared in terms of release kinetics of the complexes. In the presence of PEG, release of PEI-DNA complexes from alginate microspheres in the cell culture medium (DMEM) were enhanced and 50 % of PEI-DNA were released from the microspheres in 48 h. To understand the effect of the PEG on the surface of microspheres zeta potential analysis and microscopic examination were carried out. By increasing percentage of PEG (0, 15, 30, 50) in microspheres, less negative zeta potential value were measured. Mucoadhesion of alginate and PEG-alginate microspheres were evaluated by using modified microbalance method, and in the presence of PEG enhancement of mucoadhesion was observed. In this way a gene delivery system with a possible route through mucosa of tissues was prepared.

Techn. Hochsch., Diss., 2000--Aachen.

Designing new materials with improved or tailored properties is one of the main goals of the chemists. Two common ways are mainly used to get a material with improved or new properties: blending or chemical synthesis. Chemical synthesis is an unlimited method to get new substances with well-defined properties even it is often time consuming and not seldom costly.A rheology study has shown a considerable increase in viscosity of 1% aqueous solutions, 40 and 120 times at 550C, for the graft copolymers with a composition 67 and 80% in PNIPAM respectively as temperature increases above 350C. This behaviour is also related with a critical concentration that has been found around 0.6% for the same copolymers. Fluorescence measurements have shown that this behavior is related with the hydrophobic character and aggregation of PNIPAM chains by increasing temperature over 350C. A dynamic light scattering study in dilute aqueous solutions by varying temperature could provide more information on the kind of the transition taking place and the nature of the particles formed as temperature increases. / Ο σχεδιασμός νέων υλικών με βελτιωμένες ιδιότητες είναι ένας από τους κύριους στόχους των χημικών. Δύο είναι οι πιο συνηθισμένοι τρόποι που χρησιμοποιούνται κυρίως για τη παραλαβή ενός υλικού με βελτιωμένες ή νέες ιδιότητες: ανάμειξη ή χημική σύνθεση. Χημική σύνθεση είναι η μέθοδος όπου λαμβάνονται νέα υλικά με καθορισμένες ιδιότητες αλλά έχει ως μειονέκτημα το κόστος και είναι συχνά χρονοβόρα.Μετρήσεις ρεολογίας έδειξαν μια αξιοσημείωτη αύξηση στο ιξώδες του 1% υδατικού διαλύματος, από 40 μέχρι 120 φορές στους 550C, για συστάσεις του εμβολιασμένου συμπολυμερούς σε PNIPAM 67 εως 80% αντίστοιχα, καθώς η θερμοκρασία αυξάνεται πάνω από τους 350C. Επιπλέον αυτή η συμπεριφορά σχετίζεται με μια κρίσιμη συγκέντρωση που βρέθηκε ίση με 0,6% για τα ίδια συμπολυμερή. Μετρήσεις φθορισμού έδειξαν ότι αυτή η συμπεριφορά σχετίζεται άμεσα με τον υδρόφοβο χαρακτήρα του PNIPAM καθώς η θερμοκρασία αυξάνεται πάνω από τους 350C. Μετρήσεις με δυναμική σκέδαση φωτός σε αραιά υδατικά διαλύματα σε διάφορες θερμοκρασίες μπορούν να δώσουν επιπλέον πληροφορίες για τη μετάπτωση που λαμβάνει χώρα και τη φύση των σωματιδίων όσο η θερμοκρασία αυξάνεται.

Health Care Associated Infections (HCAIs) are a concern especially in regards to antibiotic resistance and effective treatments. Staphylococcus aureus is often the main focus for eradication and prevention procedures, however, other bacterial species are also problematic. These include Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus epidermidis amongst others. Chronic infections caused by these bacteria are often biofilm related, and include dental caries, otitis media, osteomyelitis, burns & chronic wounds, and device related & prosthetic joint infections. Prosthetic joints and indwelling devices, such as catheters, are a prime environment on which biofilms can develop. This thesis aims to look at biofilms, investigating how they are established, the development of resistance against individual antibiotics and the antibiotic concentrations required to reduce biofilm load. A novel biofilm system – the alginate bead method will be used for these experiments, The alginate bead method was developed by a previous student in the Gallagher Laboratory, due to a need to have a reliable, robust and inexpensive technique to examine formation of biofilms and antibiotic resistance. There are devices and assays available, such as the Calgary Biofilm Device, which are extensively used for these purposes. However, the cost is prohibitive. This thesis found that the development of biofilms occurs much earlier than expected, with stable, fixed formation after just four hours of growth. Depending upon the antibiotic, resistance can develop within the first two hours of growth and thereafter steadily increases. By 24 hours the biofilms are fully resistant to all the tested antibiotics. In mixed species biofilms, the two species act synergistically protecting each other against the antibiotics, resulting in a much higher antibiotic concentration required. Common antibiotics used to treat staphylococcal infections are often combined to enhance their destructive effect and prevent the development of resistance. The effects of these antibiotics, when combined was explored. Biofilm resistance against gentamicin, one of the most common antibiotics used to treat staphylococcal infections develops quickly. However, when combined with other antibiotics gentamicin resistance is delayed. As antibiotic concentrations have to be extremely high in order to have any effect on established biofilms, alternative methods need to be investigated. Any alternative approaches would be employed in conjunction with conventional therapies preventing stable biofilm formation and disrupting established biofilms. Such methods may include sugar metabolites, enzymatic disruption, D-amino acids and activation of the quorum sensing system. The main conclusion which can be taken from this work are that firstly the alginate bead method of a viable, suitable alternative to the Calgary Biofilm Device and supports biofilm formation and testing. Secondly that biofilms form and are resistant to antibiotics much earlier than expected, and extreme concentrations of antibiotics are required to have an effect. Thus the inclusion of alternative methods which disrupt biofilms would be beneficial to clinical practice. However, the alternative methods investigated within this thesis (D-amino acids and sugar metabolites) failed to show any inhibition of biofilms. There are other possible choices which would need to be investigated.

O soro de queijo, um subproduto industrial altamente poluidor, constitui-se em um substrato rico em nutrientes e de grande potencial de aproveitamento em bioprocessos. A utilização de substratos alternativos e de baixo custo para a produção de etanol, tais como resíduos industriais, vem sendo recentemente estudada, com resultados promissores. Diante deste contexto, o presente trabalho teve como objetivo otimizar a bioconversão do soro de queijo em etanol em biorreatores imobilizados usando Kluyveromyces marxianus como biocatalisador e avaliar as limitações de transferência de massa em esferas de alginato de cálcio mediante o cálculo do coeficiente de difusão. Valores similares do fator de conversão da lactose em etanol, YEtOH/S, (0,44±0,01 g g -1) foram encontrados ao testar a produção do etanol por três linhagens de K. marxianus (CBS 6556, CCT 4086 e CCT 2653) em biorreator de leito fluidizado em regime batelada, e uma diminuição na eficiência de conversão (83,3- 66,1%) e na produtividade volumétrica (0,96 a 0,78 g L-1h-1) foi observada ao aumentar a temperatura de fermentação (30-40ºC) utilizando K. marxianus CBS 6556 imobilizada. Em seguida, foram testados biorreatores de leito fixo e fluidizado operados continuamente por diferentes taxas de diluição (0,1-0,3 h-1). Os valores indicaram que o aumento da taxa de diluição leva a um decréscimo da utilização de lactose e da produção de etanol e um aumento da produtividade volumétrica (QP). Valores semelhantes do fator de conversão de lactose em etanol (YEtOH/S) foram encontrados para todas as taxas de diluição testadas, em ambos sistemas de biorreator (fixo e fluidizado). A maior produtividade volumétrica foi obtida para a taxa de diluição de 0,3 h-1 em biorreator de leito fluidizado, alcançando 87% da conversão teórica, e a maior concentração de etanol (27,9 g L-1) foi obtida com a taxa de diluição de 0,1 h-1. As imagens de microscopia eletrônica de varredura (MEV) na superfície das esferas mostraram que a imobilização em alginato de cálcio foi eficaz. O estudo da transferência de massa da lactose e do etanol em esferas de cálcio foi realizado através da medição do coeficiente de difusão com base na abordagem matemática da Segunda Lei de Fick. Diferentes condições experimentais foram testadas. Os resultados obtidos mostraram que o coeficiente de difusão independe da concentração da solução de lactose (25, 50 e 75 g L-1) e de etanol (25 e 50 g L- 1), bem como da concentração de alginato (3, 4 e 6%), e que é afetado pela temperatura (25, 30 e 35 ºC), aumentando de 4,67×10-10 m2 s-1 a 6,96×10-10 m2 s-1 para a lactose, e de 1,46×10-10 m2 s-1 a 2,68×10-10 m2 s-1 para o etanol. / Cheese whey, an industrial by-product with highly pollutant characteristics, is a substrate for cell growth, rich in nutrients and with great potential for use in bioprocesses. The utilization of alternative and low cost substrates for the production of ethanol, such as industrial waste, has been recently studied with promising results. In this context, the aim of this work was to optimize the bioconversion of cheese whey into ethanol in bioreactors using immobilized Kluyveromyces marxianus as biocatalyst and evaluate the mass transfer limitations in Ca-alginate beads by measuring the diffusion coefficient. Similar ethanol yields (0.44±0.01 g EtOH g sugar-1) were found when testing the ethanol production by three strains of K. marxianus (CBS 6556, CCT 4086 and CCT 2653) in batch fluidized bed bioreactor, a decrease in conversion efficiency (83.3 to 66.1%) and ethanol productivity (0.96 to 0.78 g L- 1.h-1) was observed with the increase of fermentation temperature (30-40ºC) by immobilized K. marxianus CBS 6556. Continuous fluidized and packed bed bioreactors with different dilution rates (0.1 to 0.3 h-1) were performed. Values indicated that the increase of dilution rate led to a decrease in lactose utilization and ethanol production and an increase in ethanol productivity (QP). Similar ethanol yields (YEtOH/S) were obtained for all dilution rates tested, in both bioreactor systems. The highest ethanol productivity (3.5 g L-1h-1) was obtained at dilution rate of 0.3 h-1 in the fluidized bed bioreactor, with 87% of the theoretical conversion. The highest ethanol concentration (27.9 g L-1) was obtained at dilution rate of 0.1 h-1. The SEM micrographies of beads demonstrated that the cell immobilization in the Ca-alginate was effective. Lactose and ethanol mass transfer studies in Ca-alginate beads was performed by measuring the diffusion coefficient based on the mathematical approach of the Fick’s second Law. Different experimental conditions were tested. Results showed that diffusion coefficients were independent from the concentration of lactose (25, 50 and 75 g L-1) and ethanol (25 and 50 g L-1), as well as from the concentration of Ca-alginate (3, 4 and 6%), but were affected by temperature, increasing from 4.67×10-10 m2 s-1 to 6.96×10-10 m2 s-1 for lactose, and from 1.46×10-10 m2 s-1 to 2.68×10-10 m2 s-1 for ethanol.

A presente dissertação, composta de dois manuscritos, buscou preencher lacunas do conhecimento no que diz respeito à desinfecção de impressões de alginato. O primeiro trabalho foi realizado com o intuito de avaliar a eficácia antimicrobiana da solução de glutaraldeído 2% através do seu comportamento bactericida e bacteriostático quando utilizada para desinfecção de impressões de alginato dos pacientes de uma clínica de ensino odontológico de uma instituição federal, durante 28 dias. Logo após a ativação de 3L da solução desinfetante e sempre após a desinfecção de 10 impressões, foram coletadas amostras de 05 mL da solução para a análise microbiológica. No período avaliado, foram imersas 70 impressões de alginato na solução desinfetante. Nenhuma amostra apresentou bactérias viáveis, caracterizando o perfil bacteriostático da solução. Todas as amostras foram capazes de inibir o crescimento de Escherichia coli, Pseudomonas aeruginosa, e Staphylococcus aureus, confirmando o poder bactericida da solução, mostrando que um volume de 3L de glutaraldeído 2% é eficaz como desinfetante de até 70 impressões de alginato ao longo do período de 28 dias. O segundo estudo preocupou-se em avaliar a eficácia do glutaraldeído 2% e do ácido peracético 0,2% em eliminar o microrganismo Staphylococcus aureus, sabidamente presente nos corpos de prova de alginato. Os corpos de prova de alginato foram contaminados com caldo de cultura contendo S. aureus. Estes foram divididos em seis grupos: controle, lavado em água estéril, imersão em glutaraldeído 2% por 5 ou 10 min e imersão em em ácido peracético 0,2% por 5 ou 10 min. Após o tratamento, cada corpo de prova foi incubado em tubo de ensaio com 20 mL de caldo BHI estéril. Posteriormente, amostras do caldo de todos os grupos foram semeadas para determinar a presença de células viáveis. Os resultados mostraram que os grupos controle e o lavado em água estéril apresentaram crescimento bacteriano e que ambos desinfetantes foram eficazes em eliminar S. aureus do alginato tanto após 10 quanto 5 min, de imersão. Os achados desta dissertação permitem concluir que: 3L de solução de glutaraldeído são eficazes para desinfetar até 70 impressões de alginato e que o glutaraldeído 2% e o ácido peracético 0,2% são eficazes na desinfecção de alginato contaminado com S. aureus. / This research made an effort to amplify the knowledge about disinfection of alginate dental impression. The aim of the first study was to evaluate the efficacy of 2% glutaraldehyde solution after successive immersions of contaminated alginate impressions of dental patients from a Dental School by analyzing its bacteriostatic and bactericidal activity through 28 days. After the disinfection of every 10 alginate impressions a 10mL sample of the disinfectant solution (05mL) was collected to be microbiological analyzed. In this period, 70 alginate impressions were immersed in the solution. No viable bacterial grouth was observed at any of the microbiology analyses. All the samples tested were able to inhibit the bacterial growth of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The bacteriostatic and bactericidal activity of 2% glutaraldehyde solution was confirmed and 3L of the solution can be safetely used for the disinfection of at least 70 impression during 28 days. The aim of the second study was to evaluate the efficacy of 2% glutaraldehyde and 0.2% peracetic acid against Staphylococcus aureus. Alginate specimens were contaminated at S. aureus culture media. Specimens were divided into six groups: control, washed in sterile water, immersed in 2% glutaraldehyde for 5 or 10 minutes and immersed in 0,12% peracetic acid for 5 or 10 minutes. The results showed that control and sterile water showed bacterial growth and that both disinfectants (glutaraldehyde and peracetic acid) showed efficacy against S. aureus for both immersion period of time (5 and 10 minutes). The findings of these studies allowed the conclusion that 3L of glutaraldehyde solution showed efficacy to disinfect up to 70 alginate impressions and that, both 2% glutaraldehyde and 0.2% peracetic acid are efficient to disinfect S. aureus contamined alginate impressions.

A mucopolissacaridose tipo I (MPS I) é uma doença autossômica recessiva causada pela deficiência da enzima α-L-iduronidade (IDUA). Essa deficiência resulta no acúmulo de glicosaminoglicanos levando a diversas manifestações clínicas. A microencapsulação de células recombinantes que superexpressam IDUA tem sido considerada uma estratégia promissora para o tratamento de MPS I. Neste contexto, o presente estudo teve por objetivo a otimização da encapsulação de células BHK (Baby Hamster Kidney) superexpressando IDUA em microcápsulas de alginato revestidas com poli-L-lisina (PLL) utilizando-se um extrusor eletrostático. Em uma primeira etapa, um estudo de otimização das microcápsulas de alginato (MC-A) foi realizado por meio de um desenho experimental do tipo Box-Behnken (software Mini-Tab®) que permitiu avaliar simultaneamente a influência da voltagem (kV), fluxo alginato/células (mL/h) e concentração de alginato (%) sobre o tamanho das microcápsulas e a atividade de IDUA. Após, as microcápsulas foram revestidas sequencialmente com PLL e alginato (MC-APA) com o objetivo de aumentar a sua estabilidade. Nas condições experimentais empregadas, MC-A e MC-APA apresentaram-se monodispersas (span < 1,22) com um diâmetro médio inferior a 350 μm, determinado por difração a laser. O revestimento alterou a morfologia das microcápsulas (microscopia eletrônica de varredura) e a sua resistência mecânica (analisador de textura), sendo observado um aumento de cerca de 6 vezes na força necessária para compressão das mesmas. O revestimento final pelo alginato (MC-APA) parece ter sido parcial de acordo com as análises de infravermelho por transformada de Fourier com refletância atenuada. Em uma última etapa, a atividade enzimática foi avaliada em modelo murino MPS I após implante subcutâneo de MC-APA. Foi observado um aumento significativo da atividade de IDUA na pele, após 30 dias de tratamento. Nas análises histológicas foi observado um infiltrado inflamatório no local da aplicação que não impediu a liberação da enzima nas condições avaliadas. No seu conjunto, esse estudo demonstra a potencialidade das MC-APA para a liberação local de IDUA. / Mucopolysaccharidosis type I (MPS I) is an autosomal recessive disorder caused by the deficiency of α-L-iduronidase (IDUA). This deficiency results in the accumulation of glycosaminoglycans leading to various clinical manifestations. The microencapsulation of recombinant cells overexpressing IDUA has been considered as a promising strategy for the treatment of MPS I. In this context, the present study aimed to optimize the encapsulation of BHK cells overexpressing IDUA in poly-L-lysine (PLL) coated alginate microcapsules using an electrostatic extruder. In a first step, a Box-Behnken experimental design (Mini-Tab® software) was carried out for the optimization of the alginate microcapsules (MC-A), which allowed to evaluate simultaneously the influence of voltage (kV), alginate/cell flow (mL/h) and alginate concentration (%) on the size of the microcapsules and IDUA activity. Thereafter, the microcapsules were sequentially coated with PLL and alginate (MC-APA) in order to increase their stability. In the experimental conditions used, MC-A and MC-APA were monodisperse (span <1.22) with an average diameter of less than 350 μm, determined by laser diffraction. The coating modified microcapsules morphology (scanning electron microscopy) and their mechanical resistance (texture analyzer), being observed a six-fold increase in the required force for their compression. The final alginate coating (MC-APA) appears to have only partially coated the microcapsules, according to the attenuated total reflectance Fourier transform infrared spectroscopy analyses. In a final step, the enzymatic activity was evaluated in a MPS I murine model after subcutaneous implantation of MC-APA. A significant increase in IDUA activity was observed in the skin at 30 days after treatment. Histological analszes revealed an inflammatory infiltrate at the application site, which did not prevent the release of the enzyme under the evaluated conditions. Overall, this study demonstrates the potentiality of MC-APA for the local release of IDUA.

Esta dissertação teve como objetivo, a preparação de hidrogéis à base de alginato contendo argila e material magnético em sua estrutura. Foram analisadas as modificações nas características físico-químicas dos hidrogéis preparados com diferentes reticulantes (CaCl2 e FeCl3) e diferentes concentrações de material magnético (1 e 3 % m/m) e argila (1, 5 e 10 %). Após isso, os hidrogéis foram avaliados quanto à capacidade de remoção de íons Cu2+ e Zn2+ de soluções aquosas. As amostras foram caracterizadas quanto à composição química por espectroscopia na região do infravermelho (FTIR), quanto à morfologia por microscopia óptica e microscopia eletrônica de varredura (SEM) e quanto às propriedades magnéticas por magnetometria de amostra vibrante (VSM). Através da técnica de difratometria de raios-X (XRD), foi possível verificar a natureza do material magnético e a dispersão da argila nos hidrogéis. A estabilidade térmica das amostras foi analisada por análise termogravimétrica (TGA). Os resultados mostraram que tanto a argila como o material magnético ficaram bem dispersos nas amostras. De forma geral, foram preparados hidrogéis com morfologia esférica, sendo que os hidrogéis de alginato de cálcio tenderam a apresentar maior resistência térmica do que os hidrogéis de alginato de ferro. Todas as amostras magnéticas apresentaram comportamento superparamagnético, porém as amostras de alginato de ferro mostraram-se quebradiças após o intumescimento em água. O tempo médio de equilíbrio de intumescimento foi de 240 minutos. Os resultados de cinética de adsorção mostraram que os hidrogéis de alginato de cálcio preparados nas condições avaliadas nesta Dissertação foram eficientes na remoção dos íons Cu2+ e Zn2+, sendo que o cobre apresentou maior afinidade pelo hidrogel do que o zinco / The aim of this Dissertation was study the preparation of hydrogels based on alginate containing clay and magnetic material in its structure. The modifications on the physicochemical characteristics of hydrogels prepared with different crosslinking (CaCl2 and FeCl3), different concentrations of magnetic material (1 and 3 % w/w), and clay (1, 5 and 10 % w/w) were analyzed. After that, the removal capacity of Cu2+ and Zn2+ from aqueous solutions was evaluated. The samples were characterized according their chemical composition by infrared spectroscopy (FTIR), morphology by scanning electron microscopy (SEM) and optical microscopy, magnetic properties by vibrating sample magnetization (VSM). Through the X-rays diffraction (XRD) it was possible to ascertain the nature of the magnetic material and the clays dispersion into hydrogels. The thermal stability of the samples was analyzed by thermogravimetry analysis (TGA). The results showed that both clay and magnetic material were well dispersed in the samples. Spherical hydrogels were prepared and the calcium alginate hydrogels had tended to present higher thermal resistance than the iron alginate hydrogels. All the magnetic samples showed superparamagnetic behavior; however iron alginate samples had proved be brittle after swelling in water. The equilibrium time of swelling was 240 minutes. The adsorption kinetics results showed that calcium alginate hydrogels prepared under the conditions evaluated in this work were efficient in the removal of Cu2+ and Zn2+, and copper showed higher affinity than zinc for the hydrogel