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Hyaluronan-CTAT hydrogels
Velcer, Tomáš ; Venerová, Tereza (referee) ; Pekař, Miloslav (advisor)
This thesis studies the properties and behaviour of phase-separated hydrogels prepared by interaction of hyaluronan with oppositely charged surfactants. Three representatives of surfactants, namely cetyltrimethylammonium bromide, chloride and p-toluensulfonate (CTAB, CTAC, CTAT), were selected for comparison. Using the method of rheology, the fact that the system of Hya-CTAT forms the most rigid hydrogels has been proved. Higher molecular weight of hyaluronan has also direct influence on the volume and stiffness of the newly formed hydrogels. Preparation methods were compared as well. Mixing the stock solutions of entry components appeard to be the most suitable. Small-angle X-ray scattering was used for determination of shape and size of surfactant's micelles, concluding that it has no effect on the volume of formed gels. The results of this study indicate that given gels are to a certain extent competitive and incorporation of hyaluronan into their structure is desirable with respect to its biological activity. This offers a potential usage of these substances in the field of medical applications.
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Nanocarriers based on hydrophobized biopolymer
Velcer, Tomáš ; Hnyluchová, Zuzana (referee) ; Venerová, Tereza (advisor)
This work studies the properties of hydrophobically modified biopolymers for potential use in targeted drug delivery. Two samples of hydrophobically modified hyaluronan were selected. The critical micelle concentration (CMC) of these samples was measured using fluorescence spectroscopy, wherein it was found that micelle formation occurs over a wide concentration region. Environment of 0,15 M NaCl causes the decrease of CMC only slightly or not at all. Using the method of dynamic light scattering, particle size was measured. One of the samples exhibited a double size distribution. DLS results are consistent with the results of fluorescence spectroscopy at issue in aggregates forming near the CMC point. Zeta potential measurements provide information about stability of the samples. The results of this study confirm that one of the studied samples seems to be a suitable candidate for the post of drug carrier for targeted delivery.
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Physical hydrogels based on biopolymers and surfactants
Velcer, Tomáš ; Lehocký, Marián (referee) ; Kráčalík, Milan (referee) ; Pekař, Miloslav (advisor)
This doctoral thesis studies the properties and behaviour of phase-separated hydrogels. These can be prepared by interaction of polyelectrolytes with oppositely charged surfactants. Negatively charged polysaccharide hyaluronan and cationic surfactant carbethopendecinium bromide (Septonex), whose properties, behaviour and utilization are described in the first two chapters of theoretical part, were selected for this role. Hyaluronan is naturally-occuring in living organisms and is known for his specific targeting to the tumour cells. Septonex is used as antiseptic and disinfectant. Experimental part of this work is focused on examination of the structure and behaviour of these types of hydrogels especially from rheological point of view. The crucial part of this study was to establish mechanical properties and their dependence on environment. This led to design further studies. Structural analysis was held using the methods of ATR-FTIR, ionic chromatography and ICP-OES helping to measure the inner content of entry materials in the gels and supernatants respectively. The last chapter deals with antimicrobial activity. The results of this study indicate a potential usage of these substances in the field of medical applications.
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Physical hydrogels based on biopolymers and surfactants
Velcer, Tomáš ; Lehocký, Marián (referee) ; Kráčalík, Milan (referee) ; Pekař, Miloslav (advisor)
This doctoral thesis studies the properties and behaviour of phase-separated hydrogels. These can be prepared by interaction of polyelectrolytes with oppositely charged surfactants. Negatively charged polysaccharide hyaluronan and cationic surfactant carbethopendecinium bromide (Septonex), whose properties, behaviour and utilization are described in the first two chapters of theoretical part, were selected for this role. Hyaluronan is naturally-occuring in living organisms and is known for his specific targeting to the tumour cells. Septonex is used as antiseptic and disinfectant. Experimental part of this work is focused on examination of the structure and behaviour of these types of hydrogels especially from rheological point of view. The crucial part of this study was to establish mechanical properties and their dependence on environment. This led to design further studies. Structural analysis was held using the methods of ATR-FTIR, ionic chromatography and ICP-OES helping to measure the inner content of entry materials in the gels and supernatants respectively. The last chapter deals with antimicrobial activity. The results of this study indicate a potential usage of these substances in the field of medical applications.
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Hyaluronan-CTAT hydrogels
Velcer, Tomáš ; Venerová, Tereza (referee) ; Pekař, Miloslav (advisor)
This thesis studies the properties and behaviour of phase-separated hydrogels prepared by interaction of hyaluronan with oppositely charged surfactants. Three representatives of surfactants, namely cetyltrimethylammonium bromide, chloride and p-toluensulfonate (CTAB, CTAC, CTAT), were selected for comparison. Using the method of rheology, the fact that the system of Hya-CTAT forms the most rigid hydrogels has been proved. Higher molecular weight of hyaluronan has also direct influence on the volume and stiffness of the newly formed hydrogels. Preparation methods were compared as well. Mixing the stock solutions of entry components appeard to be the most suitable. Small-angle X-ray scattering was used for determination of shape and size of surfactant's micelles, concluding that it has no effect on the volume of formed gels. The results of this study indicate that given gels are to a certain extent competitive and incorporation of hyaluronan into their structure is desirable with respect to its biological activity. This offers a potential usage of these substances in the field of medical applications.
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Nanocarriers based on hydrophobized biopolymer
Velcer, Tomáš ; Hnyluchová, Zuzana (referee) ; Venerová, Tereza (advisor)
This work studies the properties of hydrophobically modified biopolymers for potential use in targeted drug delivery. Two samples of hydrophobically modified hyaluronan were selected. The critical micelle concentration (CMC) of these samples was measured using fluorescence spectroscopy, wherein it was found that micelle formation occurs over a wide concentration region. Environment of 0,15 M NaCl causes the decrease of CMC only slightly or not at all. Using the method of dynamic light scattering, particle size was measured. One of the samples exhibited a double size distribution. DLS results are consistent with the results of fluorescence spectroscopy at issue in aggregates forming near the CMC point. Zeta potential measurements provide information about stability of the samples. The results of this study confirm that one of the studied samples seems to be a suitable candidate for the post of drug carrier for targeted delivery.
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