|
|
Colloid properties of hyaluronane sols
Krouská, Jitka ; Mašek, David (referee) ; Pekař, Miloslav (advisor)
Předmětem této práce bylo popsat agregační vlastnosti kyseliny hyaluronové (HA) a jejích hydrofobně modifikovaných derivátů. Za tímto účelem byly připraveny vodné roztoky kyseliny a dvou derivátů, lišící se stupněm substituce a druhem anorganické soli jako prostředím. Koncentrační řady čisté kyseliny hyaluronové a jejích derivátů byly studovány dvěma metodami, tensiometricky a spektrometricky. Povrchové vlastnosti roztoků byly měřeny s použitím kroužku Du Noüy. Zkoumáno bylo také solubilizační chování ve vodě a v chloridu sodném pomocí dvou sond: Coomassie brilantní modři a sudanu III. Amfifilní deriváty hyaluronanu mohou skutečně tvořit hydrofobní agregáty v roztoku a adsorbovat se na rozhraní vzduch–voda. Tato vlastnost je důležitá v souvislosti s transportními systémy léčiv, protože právě hydrofobní domény agregátů hyaluronanu mohou být použity jako nosiče hydrofobních léčiv. Byly zjištěny kritické agregační koncentrace roztoků derivátů hyaluronanu (tensiometricky a spektrometricky), které odpovídají právě těm koncentracím, při kterých vznikají hydrofobní domény.
|
|
|
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.
|
|
|
Utilization of thermal and structural analyses in study on the formation of polyelectrolyte complexes
Řiháčková, Barbora ; Sedláček, Petr (referee) ; Krouská, Jitka (advisor)
This bachelor thesis deals with a study of the polyelectrolyte complexes made by chitosan and humic acids. The work was motivated by the research in the field of new materials which can be potentially useful for agricultural and medical applications. A degree and a character of the interactions were studied by isothermal titration calorimetry and dynamic light scattering method. The calorimetric experiments proved that decreasing concentration of samples causes decreasing of reaction enthalpy. Moreover, the temperature changes during the titration are not influenced by water molecules as environment but mostly by the interactions between the functional groups of chitosan and humic acids. The formation of polyelectrolyte complexes was proved also by measurements of intensity of scattered light and Z-average of particle size.
|
|
|
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.
|
|
|
Hyaluronan hydrogels for medical applications
Janča, David ; Krouská, Jitka (referee) ; Venerová, Tereza (advisor)
This work studies properties of hydrogels prepared by the interaction of polyelectrolyte hyaluronate with cationic surfactant cetyltrimethylammonium bromide (CTAB) in a model physiological solution of 0,15 M NaCl. Effects of different pH and final pH of different samples of hydrogels were studied. Furthermore, stability of hydrogels was observed by fluorescence spectroscopy, where pyrene was used as a fluorescence probe, and isothermal microcalorimetry. It was found that low temperature disrupts gel integrity and it is not recommended to expose hydrogels to other than a neutral pH.
|
|
|
Characterization of medical biopolymers by ultrasound spectroscopy
Jugl, Adam ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
Using high resolution ultrasonic spectroscopy has been investigated hyaluron solutions of various molecules weights depending on their concentration and solution temperature. Furhermore, the influence of ionic strenght on the properties of solutions by dissolving hyaluronan in 0.15 M aqueous solution of sodium chloride. For comparison the properties of the hyaluronan solutions were compared with aqueous solutions of carrageenan. It was found that hyaluronan in solution behaves the same, regardless of the weight, temperature and concentration.
|
|
|
Study of thermal properties of selected coloids
Křivánková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
The bachelor thesis is focused on the study of the thermal properties of colloidal systems, especially the properties of emulsions (water, oil), which can be used in the cosmetic industry as an essential component of various lotions and creams and in the food industry. In the introduction the first defined thermo-physical processes (conduction, convection and radiation) and temperature measurement (stationary, transient). Furthermore defined physical parameters (heat and thermal conductivity, heat capacity), that are determined using transient methods. The measured data were collected and analyzed by using the EMA (Electrical Measurement Analyser) and the HarFA (Harmonic and Fractal Image Analyser). The results will be used to determine the optimum conditions for the production of cosmetics and dietary supplements.
|
|
|
Study of the interaction of hyaluronan and biocompatible amphiphilic substances
Cigánková, Hana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This thesis focuses on the study of the interactions between hyaluronan and selected phospholipids and their mixtures in water or buffer. First, the aggregation behavior of these lipids was measured, afterwards the influence of hyaluronan was studied. This behavior was investigated by fluorescence spectoscopy using pyrene as fluorescence probe. The Critical Agregation Concentration of the lipids before and after addition of hyaluronan was determined. The measurements revealed that the addition of hyaluronan has an observable influence on the aggregate behavior of the selected lipids and their mixtures.
|
|
|
Fluorescence probes in investigation of associative colloid domains.
Mischingerová, Monika ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
The aim of this thesis was to determine how the concentration of the fluorescent probe (pyrene) affects the critical micelle concentration. In this thesis were used all types of surfactants (anionic, cationic and nonionic). As representatives of the anionic surfactants were chosen sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfate (SDBS), as the cationic surfactant was chosen cetyltrimethylamonium bromide (CTAB) and as the nonionic polyoxyethylene(9.5)octylphenol (Triton X–100). The critical micelle concentration of these surfactants were measured with a pyrene at three different concentrations. All data obtained by fluorescence spectroscopy were fitted by a Boltzmann-type sigmoid. It was found out that in the case of the anionic surfactants there is some correlation between the critical micelle concentration of the surfactant and the concentration of the fluorescent probe. In both cases (SDS, SDBS) the value of the critical micelle concentration increased with increasing concentration of the fluorescent probe. For the other surfactants (cationic and nonionic) was observed no change in the critical micelle concentration values depending on the concentration of pyrene.
|
|
|
Preparation and application of physical hyaluronan gel
Kovářová, Lenka ; Krouská, Jitka (referee) ; Venerová, Tereza (advisor)
Bachelor's work is concerning by research in physical hyaluronan gel area. Research is focusing on its preparation, especially by interaction of hyaluronan (HyA) solution with opposite charged surfactant in physiological solution (0,15 M NaCl). In the first part of work I found out influence of molecular weight, concentration of original hyaluronan solution and the ratio of binding sites on hyaluronan chain and surfactant on amount of solids in gel, expressed in percent. Finally we can say, that this value is not influenced by molecular weight of HyA neither relation of binding sides. On the other side, concentration of original HyA solution has significant influence on amount of solids in gel. There was also researched process of gel swelling, where was set amount of water (in percent) able to take dried gel back. Analogical conclusion has been reached like amount of solids in gel. In other part were researched influence of hyaluronan molecular weight and the ratio of binding sites on hyaluronan chain and surfactant on formation of excimers and spectrum change by fluorescence spectroscopy. Pyrene, 1,3-bis(pyren-1-yl)propane (P3P) and prodan were used as fluorescence probes. Excimer emission showed at P3P, while there was no growth of intensity at 470 nm for pyrene. It was found that molecular weight does not affect the value of the ratio of excimer and monomer probe P3P, or the ratio of the first and third peaks of pyrene. The ratio of binding sites HyA and surfactant influence only relation of excimer to monomer (P3P probe), while influence to relation 1:3 hasn't been noticed for pyrene. I have compared spectrum of developed gel for prodan probe, relevant solid and swelled gel by return. It also served for drying and swelling process visualisation.
|
guest ::
RSS feed.