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The use of microcalorimetric methods in the study of the protective effects of chemical chaperons
Bohunská, Miroslava ; Pekař, Miloslav (referee) ; Krouská, Jitka (advisor)
This bachelor thesis deals with the study of protective substances against denaturation processes, called chemical chaperones. The theoretical part describes the general characteristics of proteins, description of selected chaperones and methods of differential scanning calorimetry. In the experimental part, the protective effects of four potential protective agents - trehalose, guanidine hydrochloride, 3-hydroxybutyrate and hydroxyectoine - were investigated on the lysozyme model protein. The protective effects of the individual substances were examined by differential scanning calorimetry (DSC), which determined the denaturation temperature of lysozyme in the presence of preservatives. Of all the chemical chaperones examined, the highest protective effect was observed with 3-hydroxybutyrate, which shifted the denaturation temperature to higher levels, and guanidine hydrochloride, which on the other hand lowered the denaturation temperature. At the same time, a reversible denaturation process was found in some substances, which was the most intense in GuHCl.
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Characterization of carrageenan by densitometry
Poledňáková, Halina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The density of the carrageenan solution was investigated by densitometry depending on temperature and concentration. Subsequently, ultrasonic velocity was examined using densitometry and high-resolution ultrasonic spectroscopy. The measurements were executed using aqueous and sodium chloride solutions of carrageenan in a broad range of concentrations. It was found that the carrageenan samples are not liable to irreversible changes of density and ultrasonic velocity in dependence on temperature and concentration . Furthermore, it was proved that carrageenan in both mediums is stable, the samples do not exhibit degradation or changes in the properties of the ionic strength effect.
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Influence of concentration of surfactant component and temperature on interactions between hyaluronan and katanionic vesicular systems
Janáková, Kristýna ; Jugl, Adam (referee) ; Krouská, Jitka (advisor)
The influence of various concentrations of surfactant component and various temperatures on interactions of hyaluronan with catanionic vesicular systems were examined using isothermal titration calorimetry. The measurements were performed at two different concentrations of surfactant component and three temperature values. The reason for studying the interactions was to explore the possibility of these systems serving as carriers of drugs in the future. Catanionic vesicular systems consisted of a cationic surfactant CTAB, an anionic surfactant SDS and of a positively charged two-chain surfactant DODAC. The solution of negatively charged hyaluronan with concentration of 0,5 mM was used for all measurements.
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Adsorption of microbial cells on model biological surfaces
Mikušová, Janka ; Krouská, Jitka (referee) ; Sedláček, Petr (advisor)
The aim of this bachelor thesis is creating sorption surface suitable for studying adsorption bacterial strain Lactobacillus rhamnosus, as representative probiotic bacterial strain. Included in the experimental part of this thesis was the process of creating sorption surface, according to the designed and especially optimized method. Optimization method comprised of preparing sorbent with sorption surface including mucin, on which was the bacterial strain Lactobacillus rhamnosus bound to, using specific interaction. UV-VIS spectrophotometry was utilized in the optimization of the sorption surface preparation for monitoring losses of mucin in solution that happens during the bondation on used substrate. Designed sorption surfaces were subjected to various physical-chemical analyses, which roles were displaying and characterisation of surface and confirming the presence of mucin. One of the major components, in the process of observing and characterization of changes in surface structure of the sorption surface, was infrared spectroscopy with Fourier transformation. Scanning electron microscopy was used for more detailed observation of the surface structure, created by adhesive interactions, which participate in probiotic bacteria adhesion. Finally, the created surfaces were used in pilot experiment, during which, the kinetics in growing bacterial culture with and without the presence of sorbent using microcalorimetry were observed. Designed sorbent appears to be a suitable mediator for detailed characterisation of bacterial adhesion, which is the first step in creating bacterial biofilm.
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Thermal properties of high performance fibre reinforced concrete
Pecháčková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
This diploma thesis is focused on the study of the thermal properties of high-performance fiber reinforced concrete HPFRC. The composites are based on a combination of steel and polymeric fibers. Typical properties of these materials include high mechanical strength, water resistence and salt penetration. HPFRCs are mainly used in the construction industry to build tall buildings. The differential transient method was used to study thermophysical variables. The theoretical part of the thesis described the types of concrete, their production, and their properties. Furthermore, thermophysical quantities and methods of their determination (stationary and transient methods, thermal analysis) are defined in the thesis. The aim of the thesis was to determine thermal properties, namely thermal conductivity and specific heat capacity. The results of the thesis can reveal changes in the composition of studied materials as well as critical temperatures for damaging the materials.
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Stability evaluation of cosmetic dispersions using centrifugal analyser
Procházková, Michaela ; Krouská, Jitka (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis is focused on the evaluation of stability of cosmetics emulsions prepared from ingredients commonly available in laboratory and compared to the stability of commercially available body lotions. In the theoretical part cosmetics emulsion and methods used to stability measurements were described. Experimental part of this work at first describes the preparation of the emulsions. Furthermore, the stability of prepared emulsion was compared to commercially available ones using the centrifugal analyser LUMiSizer. In conclusion, the test results obtained from analyser LUMiSizer have showed the stability of the commercial emulsions and two prepared samples.
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Solubilization in catanionic surfactant systems
Konečná, Anna ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with the solubilization of hydrophobic dyes in systems of positively charged catanionic vesicles. The aim of the work was to determine their solubilization capacity. Vesicular systems were prepared from oppositely charged surfactants CTAB and SDS. To increase the stability of the vesicles, cholesterol and the positively charged double-chain surfactant DODAC were added to their structure. DODAC also gave the system a positive charge. To determine the solubilization capacity, the dyes 1-Naphthol, Sudan Red G and Oil Red O were used. For sample preparation two methods were used, spontaneous and direct solubilization. The measurement was performed after 1, 2, 3 and 7 days from the preparation of the samples by UV-VIS spectrophotometry. The solubilization capacity was determined from the measured absorbance by calculation from the calibration curves. The results indicate that direct solubilization is slightly more effective than spontaneous solubilization. Of the selected dyes, 1-Naphthol is the substance with the smallest molecule, and therefore it seems to be 100% solubilized in the vesicle system.
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The gelation of hydroxyethylcellulose and hyaluronan using citric acid
Martinková, Martina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
This master's thesis deals with gelation of hydroxyethylcellulose and hyaluronan crosslinked with nontoxic crosslinking agent – citric acid. First of all, the optimalization of gelation process of hydroxyethylcellulose took place. After obtaining the product insolube in the ultrapure deionized water, a reaction mixture of hyaluronan and hydroxyethylcellulose in two different weight ratios were prepared. There was prepared solution containing only hyaluronan as the polymeric part too. Citric acid was used in concentrations of 5 %, 10 % and 20 % (w/w of polymer). These solutions of polymers and citric acid were gelated under the same conditions and the products were compared to each other using Differential Scanning Calorimetry, Thermogravimetry and Fourier Transform Infrared Spectroscopy. The products containing hydroxyethylcellulose and hyaluronan with hydroxyethylcellulose in weight ratio equal to 3 : 7 were considered crosslinked.
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Incorporation of small organic hydrophilic substances into vesicular systems
Janoušková, Vendula ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with the study of the encapsulation efficiency of hydrophilic drugs and their releasing from the aqueous core depending on the different composition of the components of individual liposomal systems. The hydrophilic fluorescent probe called pyranine was chosen as a model drug. The aim was to prepare liposomes which would be suitable for inhalation administration in terms of their properties. These liposomes would provide passive targeting with prolonged release time without causing negative side effects on the organism. We have succeeded in developing a standard operating procedure for the incorporation of hydrophilic drugs. Liposomal systems have been prepared consisting of the addition of various components as cholesterol, phosphatidic acid, pegylated phosphatidylethanolamine and trimethylchitosan. Furthermore, we were able to characterize the individual liposomal systems in terms of size, stability and encapsulation efficiency which are important physicochemical properties for further application potential.
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