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Solubility analysis of lignocellulosic substances with antioxidative efficiency
Hrušková, Lucie ; Kalina, Michal (referee) ; Kovalčík, Adriána (advisor)
One of the main obstacles to efficiently valorise lignin is its heterogeneous solubility, which varies depending on the biological origin and the method of isolation. The theoretical part of the bachelor thesis is devoted to a basic description of lignin from its structure to its specific properties, which has led to a wide range of studies on lignin. The experimental part of the thesis deals with the determination of the solubility of commercially available lignin in selected organic solvents Solubility was determined in a total of 15 pure or mixed solvents. The highest solubility of lignin was achieved in water, in which a solubility of 99.16 % was measured. For the eight best solvents, the size and stability of the dissolved particles were further analyzed. It was found that nanoparticles can be prepared using water and DMSO. Further, the antioxidant activity (expressed by TEAC parameter) and its structure (by FTIR) were determined for the dissolved lignin and its change was recorded. Based on the solubility results, two and three step fractionations were performed. Size, stability, and antioxidant activity were determined for the final fractions. The results obtained showed that during each fractionation step, characteristic functional groups were removed, thus decreasing the antioxidant activity of the resulting fractions.
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Synthesis and characterization of sulfurized polymers for electrochemical power sources
Svoboda, Lukáš ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
Batteries based on lithium-sulfur technology have the potential to increase the amount of stored energy in comparison with current lithium-ion systems while maintaining the same weight. Achieving this goal is possible due to the high theoretical energy density of sulfur, which exceeds the values of other materials used in batteries. However, these batteries suffer from several failing, which still hinder the practical use. The use of amorphous sulfur instead of its crystalline form might lead to increasing of durability and charge efficiency. Inverse vulcanization of sulfur seems to be the perspective method for the preparation of polymer sulfur because it prevents its recrystallization and stabilizes amorphous sulfur. The aim of this thesis is the preparation and study of properties of materials made of inverse vulcanized sulfur.
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Prediction of Protein Solubility
Marušiak, Martin ; Martínek, Tomáš (referee) ; Hon, Jiří (advisor)
Protein solubility is closely related to the usability of proteins in industrial use and research. The successful prediction of solubility would therefore lead to a significant saving of financial resources. This work presents new solubility predictor Solpex based on machine learning that achieved better performance on independent test set than any comparable solubility prediction tool. The predictor implementation was preceded by a study of the biological nature of solubility, evaluation of existing solubility prediction approaches, datasets building, many experiments with novel features and selection of the best features for the predictor. As the most important step in machine learning is the datasets building, this work mainly benefits from own rigorous processing of the main source of solubility data - the TargetTrack database.
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Solubility control of biodegradable starch-based packaging
Krobot, Štěpán ; Ondreáš, František (referee) ; Lepcio, Petr (advisor)
This bachelor thesis deals with the preparation and testing of biodegradable films based on starch. The aim of the thesis is laboratory preparation of foils based on various types of starch, glycerol, polyvinylalcohol and with the addition of plasticizer – citric acid. Four different types of starch and two types of polyvinyl alcohol were used. In the first series of samples, the ratio of added glycerol to starch content was varied. Samples in the second series were prepared in the same ratios, but with different PVA. A citric acid solution was added into the last series of samples. The second aim of the thesis, after pressing the films, was to determine their solubility and stability in aqueous media depending on the ratio between added glycerol to starch content, the type of polyvinylalcohol used, and the addition of citric acid to the mixture. It has been found that citric acid appears to affect the chemical structure of the films and thus their solubility in aqueous media as well as their mechanical properties. Fourier-transform infrared spectroscopy (FTIR) was used to study the structure of the films and to elucidate its effect on solubility.
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Prediction of the Effect of Mutation on Protein Solubility
Marko, Július ; Smatana, Stanislav (referee) ; Hon, Jiří (advisor)
Protein solubility is a key problem in production of functional proteins. Prediction of the effect of mutation on protein solubility could save a lot of time and money, as it would provide in silico prediction of solubility enhancing mutations before performing deep mutational scanning in laboratory. In this work, new predictor of the effect of mutation on protein solubility SoluProtMut is introduced that is based on machine learning methods. Most of the existing predictors predict the effect from the amino acid sequence. In addition to the sequence, the tool presented in this work also uses the spatial structure of the protein, which can significantly increase it's accuracy.
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Solubility and dissociation of humic acids
Kratochvílová, Romana ; Jaroslav,, Záhora (referee) ; Klučáková, Martina (advisor)
The behaviour of humic acids in aqueous solutions is closely connected to the content of acid functional groups and their dissociation abilities. The titration methods are the most often used for the research of acid-basic characteristics of humic acids, their results should lead to the determination of the content of functional groups and their pKa. However the determined values depend on many factors including the titration speed. The aim of this bachelor’s thesis is to verify the possibility of UV/VIS spectrophotometry´s use as alternative method for the determination of pKa of humic acids and to compare the gained results with so far used method according to Henderson-Hasselbach. The principle of newly used spectrophotometry method is the preparation of humic acids solutions in three different media with different pH values. Acid groups of humic acids are practically completely dissociated in intensely basic environment and the measured absorbance is caused by anion of „humate“. On the contrary their dissociation in acid environment is suppressed so much that we measure the absorbance of non-dissociated molecules of humic acids. It was found out that after the modification it was possible to use the spectrophotometry method for the determination of pKa of these substances, while the use of method was verified within the three different samples of humic acids. The optimal ratio humic acids – water and the extent of wavelength for measuring UV/VIS spectra were determined. It was proved that the values of pKa determinated by these methods better describe the real dissociation behaviour of humic acids in water than traditional Henderson-Hasselbach method. The UV/VIS spectra gained in combination with the results of pH measuring and the conductivity next showed the differences in the behaviour of differently prepared samples of humic acids.
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Dissociation behaviour of natural biocolloids
Karbanová, Kateřina ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
This diploma thesis is focused on the study of dissociation behaviour of natural biocolloids, namely humic acids and fulvic acids. Humic and fulvic acids are natural, heterogeneous, high molecular weight substances which behave as weakly acidic polyelectrolytes and they have complex not exactly described structure. They are formed by biochemical transformations of organic residues (mainly plants). They are part of the soil, water, peat, sediments and coal. Solubility of humic acids is affected by pH value. The higher the pH value is the higher the solubility is. Fulvic acids are soluble in whole range of pH values. The aim of this diploma thesis is to determine the dissociation constant for the five kinds of humic acids and four kinds of fulvic acids, which have been isolated from various natural sources. These samples were purchased from IHSS. Dissociation constants were determined by the conductometric method and a combination of measurment pH and the content of acidic functional groups in Na2SO4. UV-VIS spectrophotometry method was used to characterize the quality of humic acids and fulvic acids.
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Study of the effect of biomolecules on the solubility of poorly soluble drugs
Kheirabadi, Fatemeh ; Holas, Ondřej (advisor) ; Vraníková, Barbora (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Ondrej Holas, Ph.D. Consultant: prof. Anette Müllertz, Ph.D. Student: Fatemeh Kheirabadi Title of thesis: Effects of Proteins on Apparent Drug solubility in Fasted State Stimulated Colonic Fluids This thesis investigates the influence of proteins on the apparent solubility of drugs in fasted state stimulated colonic fluids. The investigation was conducted on a selection of compounds with varying physicochemical and plasma protein binding properties. Precisely, three different compounds named as Nilotinib, Carvedilol and Ritonavir were analyzed for their apparent solubility in three distinct protein sources: bovine serum albumin, mucin from dehydrated porcine gastric mucin type II, and collected porcine intestinal mucus. Accurate reversed-phase high-performance liquid chromatography was developed and employed as the analytical method to determine the concentration of the apparent drug solubility of the investigated compounds. The research on the solubility of poorly soluble compounds in simulated colonic fluids has been restricted. Additionally, factors such as the impact of proteins remains unexplored in biorelevant media, which could be critical for enhancing our understanding of drug...
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Study of excipients' influence on the drug dissolution from tablets
Ouzký, Miroslav ; Šklubalová, Zdeňka (advisor) ; Mužíková, Jitka (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Supervisor: Consultants: Assoc. Prof. PharmDr. Zdeňka Šklubalová, Ph.D. Mgr. Jana Brokešová, Mgr. Daniel Pěček Student: Miroslav Ouzký Title of Thesis: Study of excipientsʼ influence on the drug dissolution from tablets The aim of this work was to study the influence of excipients on the dissolution of the high-dose active substance from tablets. The tablets were compressed from the granules prepared by wet-granulation method. 11 batches of tablets which contained two different fillers: either lactose or microcrystalline cellulose, respectively; and extragranularly added disintegrant: either croscarmellose or crospovidone, respectively, in three concentration levels of 2 %, 3,7 % or 5,4 % were prepared. Tablets were packed into aluminium/PVC blisters. The paddle dissolution test was used to determine the release of the active substance into phospate buffer pH 7,2 at the time of preparation (time 0) and at the time points 1.5, 3 and 6 months of stability assay at 40 řC and 75 % relative air humidity. The results show that the drug release from tablets containing microcrystalline celulose was generally faster than from those containing lactose. The same was true for tablets to which croscarmellose was...
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Study of excipients' influence on the drug dissolution from tablets
Ouzký, Miroslav ; Šklubalová, Zdeňka (advisor) ; Mužíková, Jitka (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Supervisor: Consultants: Assoc. Prof. PharmDr. Zdeňka Šklubalová, Ph.D. Mgr. Jana Brokešová, Mgr. Daniel Pěček Student: Miroslav Ouzký Title of Thesis: Study of excipientsʼ influence on the drug dissolution from tablets The aim of this work was to study the influence of excipients on the dissolution of the high-dose active substance from tablets. The tablets were compressed from the granules prepared by wet-granulation method. 11 batches of tablets which contained two different fillers: either lactose or microcrystalline cellulose, respectively; and extragranularly added disintegrant: either croscarmellose or crospovidone, respectively, in three concentration levels of 2 %, 3,7 % or 5,4 % were prepared. Tablets were packed into aluminium/PVC blisters. The paddle dissolution test was used to determine the release of the active substance into phospate buffer pH 7,2 at the time of preparation (time 0) and at the time points 1.5, 3 and 6 months of stability assay at 40 řC and 75 % relative air humidity. The results show that the drug release from tablets containing microcrystalline celulose was generally faster than from those containing lactose. The same was true for tablets to which croscarmellose was...
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