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Effect of crosslinking on the denaturation of collagen samples from different animal sources
Ladický, Peter ; Muchová, Johana (referee) ; Sedláček, Petr (advisor)
The diploma thesis deals with the preparation, crosslinking and characterization of collagen films from various animal sources. Collagen from pig, Tilapia, horse, cow and crocodile was used to prepare collagen films. Chemical crosslinking agents EDC/NHS and Lyofix were used to crosslink the prepared films. In the experimental part, differential scanning calorimetry (DSC) method was optimized to determine the denaturation temperature of individual collagen films before and after crosslinking. In addition, the ability of films to swell and degrade has been analyzed. The presence of characteristic groups present in the collagen structure was verified using infrared spectroscopy. The sample morphology was analyzed using Scanning Electron Cryomicroscopy (Cryo-SEM). The results show that EDC/NHS is a better collagen crosslinking agent compared to Lyofix. The best source for the preparation of thermally stable films is piggy collagen, whose denaturation temperature after crosslinking with EDC/NHS was about 69 °C and could represent more than adequate substitution for cow collagen, which is currently most used in the field of tissue engineering and food industry.
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Processing stability of polyhydroxybutyrate (PHB)
Palkovský, Radim ; Figalla, Silvestr (referee) ; Tocháček, Jiří (advisor)
The aim of this thesis was to observe and to evaluate the effects of selected additives on stabilization of two poly-3-hydroxybutyrates - Biomer and Hydal. In the experimental section of the thesis,the physical properties of pure polymers, polymers with mixture of polylactid acid, boron nitride and Citroflex 4A as well as the samples with five different additives which were added to this mixture, were meassured. Whilst processing the samples, the torque inside of the kneader was recorded. Tensile strength, Young´s modulus and relative extension were evaluated using tensile tests. Next, the differential scanning calorimetry was used to determine the melting points and their changes in comparison to the pure polymers. To evaluate the thermooxidative stability, method of induction periods was used, where the amount of time needed for degradation to make the material brittle was observed and recorded. These methods determined the the Stabilizer 9000 (Raschig) as the most suitable, owing to its better thermooxidative stability and considerable relative extension. As for DHT-4A on the other hand, it was proven that within P3HB it supports degrading processes, which devaluate the processing properties of this material even more. Amongst the other additives no significant influence on the material was observed and the changes of properties were attributed to the mixture of PLA and the other substances.
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Study on protective effect of 3-hydroxybutyrate and its derivatives
Černá, Klára ; Smilek, Jiří (referee) ; Obruča, Stanislav (advisor)
The aim of this thesis is the study of chemical chaperones, as a preservative enzymes before denaturing processes. In the experimental part of the study we investigated the protective effects of five selected potential protective compounds – derivatives of 3-hydroxybutyrate – two model enzymes: lipase and lysozyme. Protective effects of potential chemical chaperones were investigated by dynamic light scattering (DLS), which was determined by the size distribution of the aggregates lipase produced depending on the temperature at the heat-induced denaturation. Further we have been used differential scanning calorimetry (DSC), which was determined by the temperature of the denaturation of lysozyme in the presence or absence of potentially protective substances. The last parameter was to determine the effect of potentially protective agents at different concentrations on the catalytic activity of lipase and determining the residual lipase activity after application of denaturing two factors – the high temperature and freezing. Of all tested structural analogues of 3-hydroxybutyrate was the highest protective effect observed (stabilization of enzyme molecules) with the succinate, which has two carboxyl groups. Conversely, 1,3-butanediol showed virtually no protective activity, indicating that the presence of carboxyl groups on the protective effect of essential. The low protective efficacy butyrate further indicates that it is essential that an effective protectant in addition to the carboxyl group contained as a further functional group – either carboxyl or hydroxyl. More significant protective effect was observed in 3-hydroxybutyrate than in 2-hydroxybutyrate. Interestingly, the effective protectant while at higher concentrations strongly inhibit the enzyme activity of the model enzyme, which is probably related to the solvation and conformations of the protein in the presence of protectant and the availability of the active site for the substrate.
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Properties and utilization of Sea-buckthorn oil
Trávníčková, Eva ; Kučerík, Jiří (referee) ; Zemanová, Jana (advisor)
This bachelor thesis deals with the properties and utilization of sea buckthorn (Hippophae rhamnoides) and sea buckthorn oil. Sea Buckthorn oil contains wide range of substances important for health, for example vitamin E, vitamin A, carotenoids, flavonoids, sterols and essential unsaturated fatty acids. Sea Buckthorn oil is commonly used in treatment of cardiovascular disease and cancer. Its antioxidant properties are of great importance; it has UV-blocking activity and anti-aging effects. It accelerates healing of injuries and burns. In this work there are methods of thermal analysis such as differential scanning calorimetry (DSC) and thermogravimetry (TG) are employed and described. These methods were used to study thermal and thermo-oxidative stability and physical-chemical behavior of the sea buckthorn oil. DSC method was used in the slow and rapid cooling regime which revealed the sensitivity of oil to the thermal history and also the fact that the resulting endotherms do not correspond to melting temperatures of sea buckthorn oil pure components. Application of TG method revealed that oxygen has only minor effect on thermo-oxidative stability; degradation of sea buckthorn oil is caused mainly by the elevated temperature.
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Development and assessment of selected properties of emulsion cosmetics
Kuchyňová, Jitka ; Souralová Popelková, Miriam (referee) ; Zemanová, Jana (advisor)
This bachelor´s thesis focuses on assessment of selected properties of emulsion cosmetic product called Soothing face mask, which is produced by SynCare company. Thesis is targeted on rheological properties of the product. Basic rheological properties were measured by Brookfield viscosimeter in experimental part of the thesis. Short part of the text is dedicated to thermic analysis field, which may provide some useful pieces of information for storage of products in cryogenic temperature and development of emulsion products with good cryogenic-temperature resistance. Chemical properties of Soothing face mask product are expressed by description of particular characteristics of cosmetic ingredients in the product.
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