|
|
Possibilities of encapsulation of particular types of macromolecules and bacteria
Kapar, Jiří ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
Presented diploma thesis is focused on testing encapsulation methods of enzymes and probiotic bacteria. In the theoretical part a summary of different encapsulation techniques used in food industry is given. Further, materials for encapsulation, above all polysaccharides are presented. Next, some procedures of encapsulation of biopolymers and microorganisms – mainly enzymes and probiotic cultures are discussed. In the experimental part methods for preparation of several types of particles based on polysaccharides and liposomes are introduced. Particles were used for encapsulation of selected hydrolytic enzymes and probiotic strains Bifidobacterium breve a Lactobacillus acidophilus. The encapsulation effectiveness was evaluated by analysis of total proteins and enzyme activities. Particles sizes and their stability in water, in selected model foods and model body fluids were observed, too. According to results obtained in this work it was found that encapsulation of enzymes into polysaccharide particles were succesfull in all types of particles (encapsulation effectivness was more than 50 %). Polysaccharide particles showed a very good stability in body fluids as well as in model foods. As the most suitable materials for enzymes encapsulation chitosan and liposomes were found. Polysaccharide particles were used also for the encapsulation of microorganisms. The stability of particles with lactic acid bacteria was similar to particles containig enzymes, very good stability was verified aslo in model foods and model body fluids. Encapsulation enables long-term stabilization of biologically active compounds as well as posibility of their transport and controlled releasing in gastrointestinal tract. Encapsulation of probiotic bacteria could preserve their viability and long-term survival until the product expiration date. Thus, encapsulation is one of the most promissing procedures for production of foods and food suplements of great quality and high additional value.
|
|
|
Study on Sol-gel Process of Agarose by Classical Rheology and Dynamic Light Scattering
Krňávková, Šárka ; Hnyluchová, Zuzana (referee) ; Smilek, Jiří (advisor)
The main aim of the bachelor thesis was characterization of hydrogels from rheological point of view and by dynamic light scattering. Rheological part of research relates with the determination of the influence of temperature on mechanical properties, gelation temperature and temperature of solidification as well as the effect of aging on mechanical properties of hydrogel. The influence of the particle size on diffusion coefficient was investigated by scattering techniques. The positive correlation between the data obtained by both types of measurement and the potencial usage of dynamic light scattering method for the characterization of hydrogels was discussed as well.
|
|
|
Influence of particle size of cosmetic pigments on final properties product
Obručová, Kateřina ; Hurčíková, Andrea (referee) ; Zemanová, Jana (advisor)
This diploma thesis is focused on the study of the influence of the of size cosmetics pigments on the properties of the final product. This effect was studied on samples of make-up given by industry partner. Make-up samples were measured by the rheology method and the yield stress of all samples was determined. Scanning electron microscopy was used to determine the size and shape of the pigment particles. Particle size was also measured by dynamic light scattering, but the results were influenced by forming aggregates. To easier determination of the types of pigments in the sample was determined elemental composition of the pigments (Ti, Fe, O, Al) by EDS detector. Due to the unknown composition of make-up, the information was supplemented by X-ray powder diffraction (XRD) analysis, and it was possible to determine the compounds TiO2 (anatase and rutile), FeOOH and Fe2O3. The results obtained by these methods showed what pigments can be found in make-up samples, what their sizes and shapes are. It has been shown that the smaller the pigments are, the higher the viscosity and yield stress of the final product. The higher these quantities, the harder it is to handle the product.
|
|
|
Study on Interconnection between Structure and Rheological Properties of Hydrogels on Macro and Microscopic Level
Lepíková, Jana ; Klučáková, Martina (referee) ; Kalina, Michal (advisor)
Diploma thesis main goal is to obtain new pieces of knowledge about relationship between hydrogel structures and its flow and transport properties. Thesis is mainly focusing on combining pertinent biopolymers into model hydrogels based on agarose. Then perform correlation of results obtained by diffusion methods, and by rheologic measurements on macroscopic and microscopic level. Properties of hydrogels were measured by selected rheologic measurements, dynamic light scattering method, and correlative fluorescence spectroscopy. From these methods various parameters (MSD modules, values of complex viscosity) were obtained. Afterwards transport properties of prepared hydrogels were studied by observing Rhodamine 6G diffusion. Here two different approaches were used. From macroscopic perspective, simple principles of mass diffusion from dye solution to cuvettes filled with hydrogels containing individual biopolymers were used. From microscopic perspective, dye was added during the sample preparation and then the mass diffusion was investigated using FCS. Based on evaluated results it was discovered that added biopolymers don’t influence properties of carrier medium, in this case agarose hydrogels. During the study of prepared hydrogels’ reactivity and barrier properties some differences were observed. Charge of biopolymer and its charge density were discovered as main factors influencing transport of charged solutes into prepared hydrogels.
|
|
|
Crystallization of microbial polyesters - methods and biological consequences
Liczka, Jan ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The aim of this bachelor thesis was to test suitable methods for preparation of amorphous form of microbial polyesters and to perform model experiment to study a kinetics of crystallization of prepared polyesters. The theoretical part deals with PHA characteristics and various methods of isolating PHB granules from bacterial cells. In the experimental part, measuring techniques such as analytical centrifugation, dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR) were tested to characterize the properties of PHB granules. Furthermore, an experiment was performed to isolate native PHB granules from Cupriavidus necator using lysozyme, deoxyribonuclease and cell disruption by ultrasonification. The results of the analyzes showed that the granules were either isolated amorphous only in the wet and crystallized upon drying, or that the granules were completely amorphous but not isolated from the bacterial cell.
|
|
|
Utilization of thermal and structural analyses in study on the formation of polyelectrolyte complexes
Řiháčková, Barbora ; Sedláček, Petr (referee) ; Krouská, Jitka (advisor)
This bachelor thesis deals with a study of the polyelectrolyte complexes made by chitosan and humic acids. The work was motivated by the research in the field of new materials which can be potentially useful for agricultural and medical applications. A degree and a character of the interactions were studied by isothermal titration calorimetry and dynamic light scattering method. The calorimetric experiments proved that decreasing concentration of samples causes decreasing of reaction enthalpy. Moreover, the temperature changes during the titration are not influenced by water molecules as environment but mostly by the interactions between the functional groups of chitosan and humic acids. The formation of polyelectrolyte complexes was proved also by measurements of intensity of scattered light and Z-average of particle size.
|
|
|
Influence of the preparing of a biopolymer-surfactant complex on its stability and solubilization properties.
Pilgrová, Tereza ; Burgert,, Ladislav (referee) ; Mravec, Filip (advisor)
Influence of the preparing of a biopolymer-surfactant system on its solubilization properties and stability was investigated by using fluorescence spectroscopy and dynamic light scattering methods. Investigation was made on complex of native hyaluronan with cationic surfactant cetyltrimethylammonium bromide (CTAB). System has been studied in aqueous and in saline solutions. The effect of temperature of stock solutions and freezing effect on subsequent properties were investigated. Further was examinated, what effect has a way of introducing fluorescent probe into the system on subsequent solubilization properties. It was found that the conditions of preparing of biopolymer-surfactant system have a significant effect on the solubilization properies and stability of complex.
|
|
|
Utilization of biosurfactants for incorporation of hydrophobic domains into modern controlled-release systems
Nešpor, Tomáš ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This work deals with the current topic of carrier systems. Since the biggest problem is the passage of hydrophobic drugs through the bloodstream, or through universal body barriers (eg blood-brain), it is necessary to chemically modify these carriers in order to be able to administer hydrophobic substances effectively. Based on a literature search, several systems are designed and subsequently studied, in which there is a presumption of possible use for carrier systems and at the same time they have biosurfactants incorporated in them due to their ability to solubilize hydrophobic molecules. The theoretical part of this work will describe the individual biosurfactants, the process of their production, their physicochemical properties, and the possibility of their use in carrier systems. At the same time, the individual carrier systems, the procedure of their preparation, the possibilities of their use are described, and their advantages and disadvantages are also compared. In the practical part, the screening of both individual substances and their mutual interactions, as well as methods used to study the emerging structures is then performed. The study of molecular interactions is primarily performed using the technique of dynamic light scattering. The next part describes the optimization of hydrogel formation with incorporated biosurfactants in their structure and then the formed gels are subjected to rheological and solubilization tests. The study of the internal structure of these gels is performed using a scanning electron microscope.
|
|
|
Catanionic vesicular systems
Repová, Romana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with catanionic vesicles. The aim of the study was to prepare and characterize these systems. The catanionic vesicles are composed of cationic (CTAB, CTAC, TTAB, DTAB) and anionic surfactants (SDS). The physical stability of the vesicles was enhanced with the addition of cationic surfactant DODAC.The catanionic vesicles were characterized by the measurement of the dynamic light scattering, zeta potencial and fluorescence correlation spectroscopy. The size and stability of the system were determined using dynamic light scattering. Difussion coefficient of the system was analyzed using fluorescence correlation spectroscopy.
|
|
|
Study of interaction in biopolymer-surfactant system
Sovová, Šárka ; Mondek, Jakub (referee) ; Pilgrová, Tereza (advisor)
Interaction between biopolymer-surfactant and stability of arising complexes were investigated using dynamic light scattering method Stability of the system and interactions between native hyaluronan and cationic surfactant cetyltromethyl-amonium bromide in aqueous solution depending on preparation method were investigated. System was prepared either adding CTAB to hyaluronan causing sequential micelle’s formation, or adding hyaluronan to already formed micelles. It was found out that preparing method influences properties of arisen complexes. Molecular weight of hyaluronan has an inconsiderable effect on interaction against to concentration of hyaluronan, which influences interaction of component significantly.
|
guest ::
