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Study of interaction of negatively charged vesicular systems with polycations
Repová, Romana ; Klučáková, Martina (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with the preparation and characterization of negatively charged catanionic vesicular systems and their combination with selected polycations. The catanionic vesicular system was prepared by mixing of two oppositely charged surfactants SDS and CTAB. The negative charge as well as the stability of the vesicular system was provided by the incorporation of phosphatidic acid. Polycations, DEAE and TMC, have been selected for use in a pharmaceutical applications. Characterization of the prepared systems was performed by measuring DLS and ELS. The results indicate that we were able to prepare stable negatively charged vesicles that were eligible to non-covalently interact with selected polycations.
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Characterization catanionic vesicular system by HRUS
Kopřivová, Hana ; Sovová, Šárka (referee) ; Hurčíková, Andrea (advisor)
This bachelor thesis is about catanionic vesicular systems, which could serve as carriers of drugs or genes in the future. These systems are prepared from the cationic surfactants CTAB and DDAC, the anionic surfactant SDS and cholesterol, which serves as a stabilizer. In the experimental part, these vesicles were characterized by high-resolution ultrasonic spectroscopy. The behavior of systems with different percentages of cholesterol was monitored. As next, the temperature properties of the vesicles were studied using temperature scans between 10 °C and 65 °C. The density of the samples was examined by densitometry at temperatures of 25 °C and at a human body temperature of 37 °C.
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Ecotoxicity of cholesterol-lowering-drugs
Königsmarková, Kristýna ; Vávrová, Milada (referee) ; Zlámalová Gargošová, Helena (advisor)
This bachelor thesis is focused on the ecotoxicological testing of blood cholesterol lowering drugs. At first it considers the issue from a theoretical point of view – describes the effect of residual drugs on the environment, the distribution of hypolipidemics, the risks of elevated cholesterol, then deals with ecotoxicology and introduces the principles of ecotoxicological testing. In the experimental part, these following drugs were tested: Corsim, Atoris, Lipanthyl Supra, Lipanthyl 267M. In addition, clofibric acid – the metabolite of fibrates was tested. Residues of these drugs are found mainly in the aquatic ecosystem, that is why tests of aquatic organisms have been used to evaluate ecotoxicity. Test organisms were Thamnocephalus platyurus, Lemna minor and Vibrio fischeri. LC50, EC50 and IC50 values were determined on the basis of test results. Using these values, the ecotoxicity of the above mentioned hypolipidemics was evaluated.
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Mixed lipids and their interaction with biopolymers
Cigánková, Hana ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
This thesis focuses on the study of interactions between hyaluronan and lipid DOTAP and its mixtures with DPPC in water. First, the aggregation behavior of the lipid itself and its mixtures was measured, afterwards the influence of hyaluronan in different concentration was studied. Further the fluorescence anisotropy of fluorescence probe DPH in these mixtures and influence of cholesterol was measured. These properties were investigated by fluorescence spectoscopy using pyrene and DPH as fluorescence probes. The measurements revealed that the addition of hyaluronan has observable influence on the aggregation behavior of the lipid DOTAP and its mixtures with DPPC and that cholesterol influences liposomes fluidity.
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New amphiphilic ion pairs for the preparation of vesicular systems
Strnadová, Martina ; Kalina, Michal (referee) ; Mravec, Filip (advisor)
The bachelor thesis is focused on the preparation of the new vesicular systems. The aim of this work is to create the most stable system and find out the most optimal working method for its production. The compared parameters were the energy used for dispersion, the molar percentage of cholesterol added, and the type of double-stranded positively charged surfactant. The whole system consisted of negatively charged surfactant sodium dodecyl sulfate and positively charged surfactant septonex. Each system was compared over time to determine stability based on the size of the particle, zeta potential, and turbidity of the solution. By the method of dynamic light scattering, particle size and polydispersity coefficient were measured. On the other hand, the zeta potential was determined by electrophoretic light scattering. The result of the thesis presents the most suitable parameters of ultrasonic dispersion, the molar proportion of cholesterol, and the use of cationic surfactant. Based on these parameters, it is possible to create a physically stable system for a long period of time, thanks to which such a system can be used in the future for other applications.
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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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Interaction of negatively charged vesicular systems based on ionic amphiphilic pairs with polycations
Fardová, Lucie ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This work is focused on the preparation of negatively charged vesicular systems from amphiphilic pairs deprived of counterions and their interaction with the polycation. First, vesicular systems were prepared from the surfactants sodium dodecyl sulfate and cetyltrimethylammonium bromide. The addition of cholesterol and phosphatidic acid stabilized and at the same time gained a negative charge. Subsequently, there was an interaction with the polycation diethylaminoethyl-dextran hydrochloride. The systems were investigated by the measuring of particle size, zeta potential, generalized polarization and anisotropy. The measurement of generalized polarization was enabled with the laurdan probe and measurement of anisotropy was performed with the introduction of the 1,6-diphenyl-1,3,5-hexatriene probe. The results indicate the successful preparation of stable, negatively charged systems that interacted with positive diethylaminoethyl-dextran hydrochloride, which affected the behavior of the outer membrane but not the inner. The systems were still stable.
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Stability of vesicular systems using fluorescence spectroscopy techniques
Máčala, Jakub ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This thesis is focused on possibility of studying stability and fusion of catanionic vesicles with Förster resonance energy transfer. The mainly used technique was Time-Correlated single photon counting. Firstly, excitation and emission spectra of chosen probes were measured and donor-acceptor pairs were suggested: 5-hexadecanoylaminofluorescein with Octadecyl Rhodamine B, Bodipy 493/503 with rhodamine or DiI, perylene with fluorescein, DiO with DiI. Then, time-resolved measurements of suggested pairs from environment of catanionic vesicles with different content of cholesterol were made in order to track the FRET associated with fusion of vesicles. It was found out, that it is not possible to use DiO as a donor because of it’s inefficient solubilisation into vesicles. It is also not possible for Bodipy to be used as a donor, because of it‘s excimer formation. In case of using fluorescein as a donor, it was found, that there is ongoing homo-fret between fluorescein molecules. Thanks to this, fusion was tracked by addition of unstained vesicles. It was also possible to track fusion in longer period of time. Also perylene-fluorescein pair was found to be capable of tracking the fusion, but with the exception of vesicles with content of cholesterol of 43 mol. %, tracking of fusion was possible only in short period of time.
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Characterization of liposomes as precursors for the preparation of models of cellular membrane using scattering techniques
Gjevik, Alžběta ; Kalina, Michal (referee) ; Mravec, Filip (advisor)
The bachelor thesis presents a cellular membrane design based on lecithin, cholesterol and POPG basis. It summarizes formation mechanisms, optimization techniques and characterization methods of model cellular membranes. It focuses on preparation of liposomes with various lipid compositions as precursors for model membranes preparation and characterization. Small unilamellar liposomes were formed by thin layer evaporation, thin layer rehydration in phosphate buffer and sonication. Size and stability (-potential) of formed liposomes were measured using dynamic light scattering. Successful supported lipid bilayer formation on glass surface by vesicular fusion was tested using the most stable lipid composition. SLB was characterized by Z-scan fluorescence correlation spectroscopy.
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Development of electroanalytical methods for detection of cholesterol, 7-dehydrocholesterol and cholecalciferol
Benešová, Lenka
Steroidival substances are an integral part of the human organism, such as bile acids, steroid hormones, vitamins. The most important sterol in whole organism is cholesterol, which is cornerstone of the all cell membranes. It is involved in important processes in the body, but its storage in blood vessels in the formo f low-density lipoprotein (LDL) is crucial of reason serious health diseases as atherosclerosis, myocardial infarction and others. 7-dehydrocholesterol is a precursor of cholesterol and another sterol compound studied by me, cholekalciferol, also known as a vitamin D3. Deficiency of 7-dehydrocholesterol reductase is the main indicatior of the possible genesis of Smith-Lemli-Opitz syndrome. One of the goals of this thesis was developed a suitable electrochemical method to facilitate the diagnosis of this syndrome from plasma and amniotic fluid in the prenatal and postnatal phases of pregnancy. Within the framework of this thesis were developer electrochemical methods in a batch and flow arrangement for detection of the above-mentioned sterols, namely cholesterol, 7-dehydrocholesterol and cholekalciferol. It was wokered in the medium contain perchloric acid or its salt sodium perchlorate in acetonitrile as supporting electrolyte. It was worked in the wide range of working disc...
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