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Phospholipids as the basis of biodegradable delivery systems
Burdíková, Jana ; Čeppan, Michal (referee) ; Mravec, Filip (advisor)
This thesis is focused on investigation of phospholipid-hyaluronan system. First, appropriate method for preparation of bulk solution of phospholipid/lipid and suitable fluorescence probe were chosen. Sonification was selected as a method for preparation of bulk solution and pyrene was chosen as a fluorescence probe. From the group of phospholipids lecithin was selected. Next to phospholipid, lipid with no phosphate group (DPTAP) was utilized for comparison, alternatively a mixture of lipid (DPTAP) and phospholipid (DPPC). Instead of hyaluronan another polyelectrolytes (sodium polystyrene sulfonate, sodium alginate) were used too. Measurements were performed in water environment and in phosphate buffer saline (PBS). All investigation was accomplished by fluorescence spectroscopy and dynamic light scattering.
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Time-resolved fluorescence of system polymer-surfactant
Mondek, Jakub ; Čeppan, Michal (referee) ; Mravec, Filip (advisor)
In this diploma thesis was studied time-resolved fluorescence in polymer-surfactant system. At first aggregation numbers of cationic (cetyltrimethylammonium bromide), anionic (sodium dodecylsulfate) and nonionic (Triton X-100) surfactants were studied by steady-state and time-resolved fluorescence spectroscopy. These two methods were compared. Aggregation numbers by steady-state method were always lower than aggregation numbers measured by time-resolved method. Steady-state method of determination aggregation numbers is useless for surfactants with high aggregation number and for aerated samples. Addition of hyaluronan to surfactant system was studied. There was observed change in aggregation number after addition of hyaluronan and change in percentage of dynamic quenching after addition of hyaluronan. Hyaluronan affected aggregation number of cetyltrimethylammonium bromide and Triton X-100. Hyaluronan increased percentage of dynamic quenching in cetyltrimethylammonium bromide and in Triton X-100. Pyren in sodium dodecylsulfate was quenched by sphere of action with negligible percentage of dynamic quenching and addition of hyaluronan had no effect on quenching. As next goal of this thesis, the determination of the position of fluorescence probe pyrene in cetyltrimethylammonium bromide, sodium dodecylsulfate and Triton X-100 micelles was chosen. Position of pyrene changed with charge and structure of micelles. Next was studied how percentage of dynamic quenching by iodide compounds changes with different charge of micelle. In all cases majority of dynamic quenching was calculated.
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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.
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Microrheology in study of biopolmer colloids.
Hnyluchová, Zuzana ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
A new method for determining the viscoelastic properties of materials was introduced and investigated. Results of three groups of samples obtained using one particle microrheology method, DLS microrheology method and classical rheology method were compared to be sure of correctness of measurements. As a model system were chosen mixtures of glycerol of different viscosities. In case of samples containing glycerol, results were also compared with tabulated values. Hyaluronan of various molecular weights was used as a biopolymer and polystyrene particles were used for microrheology. It was confirmed, that viscosity values of biopolymer samples obtaining by each method are comparable.
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Interactions of aminoclays with natural polyelectrolytes
Jančík Procházková, Anna ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
This thesis deals with the preparation of products of interactions of aminoclay with natural polyelectrolytes. Sodium hyaluronate was chosen as the natural polyelectrolyte. The concentration and volume ratio of solutions of aminoclay and natural polyelectrolyte which led to the formation of any type of product were studied. The resulting coagulates were characterized by microscopy, FTIR spectroscopy and rheology. Furthermore the possibility of interactions with fluorescent probes was studied.
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Microrheological study hyaluronan solutions after exposure to low temperatures
Habánková, Eva ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
The aim of this bachelor thesis is to study the influence of a repeated freezing and thawing process to hyaluronan solutions. The thesis is meant to determine if repeatedly exposing hyaluronan solutions to low temperatures may change the arrangement of the polymer chains and develop weak interactions between these chains. In the thesis the applicability of the two microrheological methods was verified and these were single particle microrheology and dynamic light scattering. For microrheological measurements we used polystyrene particles with a diameter of 0,5 m. There was an effort to determine changes in the structure of hyaluronan solutions by changing the dependence of mean square displacement of particles on time and by changing viscosity of the hyaluronan solutions. Infrared spectroscopy was used as the accompanying method but it proved to be unsuitable for this purpose.
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Preparation of humic hydrogels for appliaction in cosmetics
Pavlicová, Renata ; Mravec, Filip (referee) ; Sedláček, Petr (advisor)
This bachelor´s thesis is focused on the preparation and characterization of hydrogels containing humic substances and assessment of their potential usefulness in cosmetic practice. Main objective of the work was to develop a literature review focusing on the potential use of humic substances in the cosmetics and pharmaceutical industries. Furthermore, the aim was to prepare model hydrogels addition of soluble humic substances in traditional cosmetic compositions and their characterization by basic methods of analysis parameters. The main investigated parameters were consistency resulting gels (assessed subjectively and subsequently by rheology), their internal pH and dry matter. The experimental results showed that incorporation of humic substances into hydrogels resulting gels acceptable characteristics for further use in cosmetic applications.
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Study of system based on phospholipids for sonographical application.
Überall, Martin ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
The aim of this thesis was to determine solubilizing capacity of surfactants and phospholipids using the UV-VIS spectrophotometry. The concentrations of solubilized substances within these systems was further determined. From the surfactant group, three representatives were selected, cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS) and Triton X-100. From the phospholipid group, lecithin and commercially available SonoVue® were chosen. The solubilizing capacity was determined using hydrophobic solutes Sudan Red G (SRG), Oil Red O (ORO) and 1-naphtol in order to obtain a model system of solubilized drugs or vitamins which are also hydrophobic. The behavior of solutes in surfactants was determined in a moderate polar medium of physiological saline (0.15 M NaCl), the behavior of solutes in lecithin was conversely determined in Mili-Q water medium. The determined concentration of solubilized hydrophobic solutes inside the micelles of surfactants is within the range of tens to hundreds of micromoles per liter. With increasing concentration of surfactant increases the concentration of solubilized solutes. The results obtained in this work can be used for further experiments and research focused on solubilization of drugs in contrast agents used in ultrasonography.
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Study of surface tension of systems applied in ultrasonography.
Říkovská, Klára ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
Surface tension of sonography systems was investigated using several experiments. These experiments were comprised of measurements of surface tension using BPA-800P tensiometer. The influence of surface tension of commercial substance SonoVue®, which contains in its structure two types of phospholipids, was studied more detailed. Other phospholipids were studied to comparison with SonoVue®. All substances were dissolved in saline (0,15 M NaCl). Effect of gas type on microbubbles formation and surface tension was investigated. Some samples were studied using du Nüy ring method. It was found that gas constructing the microbubbles (air or SF6) has no impact to the surface tension value. Production of foam on the surface of solutions has an impact on the value of the surface tension. This foam degreases the surface tension. Gas pressure is significant to comparison of measured data.
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Determination of residual substances from the preparation of colloidal systems based on biopolymers
Borůvková, Tereza ; Vávrová, Milada (referee) ; Mravec, Filip (advisor)
Volatile organic compounds could be isolated and concentrated from liquid solution using methods, which are based on analysis of equilibrium gas phase, because of their volatility. The aim of this bachelor´s thesis is determination the amount of residual tert-butanol, belonging to volatile organic compounds, in the samples after lyophilisation. Samples were prepared by mixing hydrofobic sonde and hydrofilic hyaluronan. For mixing these components it is necessary to add organic solvent tert-butanol, which ensures stable environment. Thanks to its presence mixing of probe and hyaluronan occurs. Consecutive lyopfilisation of the sample leads to the disruption of a water cover of hyaluronan and nonpolar hydrogen atoms, which are hidden in it, can interact with hydrofobic probe. Bonding the probe is important in oncology, where this fact could be used in targeted distribution of pharmaceuticals. However presence of tert-butanol is unacceptable in the final product, mainly in medical applications. The object this study is the minimization of residual tert-butanol amount in final lyophilised cake. The method of equilibrium gas phase analysis (static Head-Space) by gas chromatography with flame ionization detection (GC/FID) was used for the determination of its content.
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