CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Os isomalto-oligossacarÃdeos prÃ-biÃticos sÃo carboidratos capazes de chegar intactos ao intestino grosso, onde sÃo metabolizados pelas bifidobactÃrias e lactobacilos ali presentes, estimulando o seu crescimento e proporcionando efeitos benÃficos à saÃde. Podem ser obtidos por sÃntese enzimÃtica, entretanto, os substratos nÃo consumidos, frutose e dextrana tambÃm estÃo presentes apÃs a formaÃÃo dos isomalto-oligossacarÃdeos. Este trabalho teve por objetivo a sÃntese enzimÃtica e a separaÃÃo de isomalto-oligossacarÃdeos prÃ-biÃticos por cromatografia de troca iÃnica em escala preparativa. A primeira parte da tese consistiu em investigar o efeito de diferentes estratÃgias de alimentaÃÃo de sacarose e maltose ao meio reacional sobre o alongamento da cadeia dos isomalto-oligossacarÃdeos. A sÃntese foi realizada adicionando-se 1UI/mL da enzima ao meio reacional contendo como substrato os aÃÃcares sacarose e maltose. Na primeira estratÃgia, houve a adiÃÃo somente de sacarose ao meio reacional a cada 2 horas, durante 8 horas. Na segunda estratÃgia, houve a adiÃÃo da mistura de sacarose e maltose ao meio reacional a cada 2 horas, durante 8 horas. Na terceira estratÃgia houve, a cada hora, a adiÃÃo da mistura de sacarose e maltose, durante seis horas. ApÃs este perÃodo, houve adiÃÃo somente de sacarose durante seis horas. A Ãltima estratÃgia de alimentaÃÃo, resultou no alongamento da cadeia dos isomalto-oligossacarÃdeos atà grau de polimerizaÃÃo nove, alÃm do aumento da concentraÃÃo dos mesmos (79,04 g/L) a nÃveis consideravelmente superiores aos reportados na literatura. Na segunda parte da tese, foi avaliada a influÃncia da forma catiÃnica de fases estacionÃrias cromatogrÃficas na separaÃÃo dos isomalto-oligossacarÃdeos. As isotermas de adsorÃÃo dos isomalto-oligossacarÃdeos, monossacarÃdeos e dissacarÃdeos foram determinados em colunas preparativas empacotadas com resina de troca iÃnica em diferentes formas catiÃnicas (K+, Ca2+, H+ e Na+) à 25ÂC. Todas as fases adsorveram os aÃÃcares com capacidade variÃvel, segundo a ordem de afinidade: frutose > glicose > maltose > IMOs com grau de polimerizaÃÃo crescente. Foi verificado que a forma catiÃnica H+ apresentou melhor desempenho para ser utilizada em unidades de leito mÃvel simulado permitindo a separaÃÃo de isomalto-oligossacarÃdeos prÃ-biÃticos com menor diluiÃÃo e maior produtividade. No entanto, a resina na forma K+ apresentou rendimento apenas ligeiramente inferior, sendo mais compatÃvel com os requisitos de tamponamento da reaÃÃo enzimÃtica. / Prebiotic isomalto-oligosaccharides (IMOs) are carbohydrates able to reach the large bowels intact, where they are metabolized by bifidobacteria and lactobacillus, stimulating their growth and providing beneficial health effects. They may be obtained by enzymatic synthesis using sucrose and maltose as precursors. However, non consumed substrates, fructose and dextran are present together with the produced isomalto-oligosaccharides. This work aimed the optimization of the enzymatic synthesis and the separation of prebiotic isomalto-oligosaccharides by ion exchange chromatography on semipreparative scale. The first part of the thesis investigated the effect of different feeding strategies of sucrose and maltose to the reaction medium on the chain elongation of isomalto-oligosaccharides. The synthesis was performed by adding 1UI/mL of enzyme to reaction medium containing sucrose and maltose as substrate. In the first strategy, only sucrose was added to the reaction medium every 2 hours for 8 hours. In the second strategy, a mixture of sucrose and maltose was added to the reaction medium every 2 hours for 8 hours. In the third strategy, at every hour, a mixture of sucrose and maltose was added for six hours. Then, only sucrose was added at every hour for more six hours. The latter strategy resulted of isomalto-oligosaccharides chain elongation up to degree of polymerization of 9. The concentration of IMOs (79.04 g/L) was also observed. In the second part of the thesis, the influence of the cationic form of the chromatographic stationary phase in the isomalto-oligosaccharides separation was evaluated. Adsorption isotherms of isomalto-oligosaccharides, maltose, glucose and fructose were determined in preparative columns packed with ion-exchange resin in different cationic forms (K+, Ca2+, H+ and Na+) at 25ÂC. All stationary phases adsorbed the sugars with variable capacities, following the same order of affinity: fructose > glucose > maltose > IMOs with increasing degrees of polymerization. It was found that the resin in H + form presented the best performance to be used in simulated moving bed units, allowing for the separation of prebiotic isomalto-oligosaccharides with lower dilution and higher productivity. Nevertheless, the resin K+ had only a slighty inferior performance and this cation is more compatible with buffer requirements of the enzymatic synthesis.

<p style="text-align: justify;">U ovom radu sintetisani su hidrogelovi na osnovu akrilamida i akrilne kiseline, radikalnom polimerizacijom, primenom konvencionalne i mikrotalasne metode sinteze. Varirani su početni odnosi monomera i udeo umreživača, u cilju ispitivanja uticaja sastava reakcione sme&scaron;e na svojstva dobijenih hidrogelova. Optimizovani su uslovi sinteze u mikrotalasnom polju kao brže, jednostavnije i ekonomičnije metode. U cilju uspostavljanja korelacije između mehanizma sinteze, strukture i svojstava dobijenih hidrogelova, primenom relevantnih metoda karakterizacije, upoređena su apsorpciona, reolo&scaron;ka, toplotna i strukturna svojstva hidrogelova dobijenih dvema metodama.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Ustanovljeno je da se mikrotalasnom metodom sinteze na brži i jednostavniji način uz smanjen utro&scaron;ak vremena i energije dobijaju hidrogelovi konkurentni onima koji se dobijaju konvencionalnim zagrevanjem u vodenom rastvoru. Drugi deo doktorata obuhvata sintezu hidrofilnih polimernih mreža na osnovu natrijum karboksimetilceluloze (NaCMC) i karboksilnih kiselina, od kojih je jedna serija sintetisana prožimanjem linearnim kopolimerima akrilamida i akrilne kiseline u cilju povećanja potencijala primene u floku-lacione svrhe. Rezultati ispitivanja svojstava bubrenja, strukturnih toplotnih i flokulacionih svojstava pokazali su međusobno slaganje. Dobijeni rezultati pokazali su da od primenjenih karboksilnih kiselina, linunska kiselina u udelu od 15% u odnosu na masu NaCMC daje hidrogelove najboljih svojstava. Kombinacijom ove mreže sa kopolimerom akrilamida i akrilne kiseline u masenom odnosu 10/90, stvara se teorijska platforma za dobijanja flokulanta koji bi mogao da pokaže visoku efikasnost u preči&scaron;ćavanju vode u kojoj dominiraju pozitivno naelektrisane čestice, pravilnim izborom parametara flokulacije.</p> / <p>In this paper, hydrogels based on acrylamide and acrylic acid were synthesized using conventional and microwave synthetic methods via free-radical polymerization. The initial monomers ratio and amount of crosslinking agent were varied in order to investigate the effect of the composition of the reaction mixture on the properties of the obtained hydrogels. The conditions of synthesis in the microwave field as faster simpler and more economical method have been optimized. In order to establish a correlation between the mechanism of synthesis, structure and properties of the obtained hydrogels using the relevant methods of characterization, the absorption, rheological, thermal and structural properties of the hydrogels obtained by the two methods were compared. It has been found that the microwave synthesis is a faster and simpler method, which enables reduced consumption of time and energy and produces hydrogels competitive to those ones obtained by conventional heating in aqueous solution. The second part of the thesis includes the synthesis of hydrophilic polymer networks based on sodium carboxymethylcellulose (NaCMC) and carboxylic acids, whereby one series is synthesized by interpenetration of the network using the linear acrylamide and acrylic acid copolymers in order to increase the potential application of hydrogels for flocculation purposes. The results of measurements of swelling, structural, thermal and flocculation properites have shown mutual agreement. The obtained results have shown that among applied carboxylic acids, citric acid in the amount of 15% per mass of NaCMC, has given the hydrogels with the best properties. The Combination of this network with a copolymer of acrylamide and acrylic acid in a mass ratio of 10/90 has created a theoretical platform for the production of flocculant which could show high efficacy in purifying of water dominated by positively charged particles.</p>