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Aggregation processes in amphiphil-polymer system
Šejnohová, Michaela ; Márová, Ivana (referee) ; Pekař, Miloslav (advisor)
This Bachelor´s thesis is focused on the exploration of polyelectrolyte-surfactant system by fluorescence spectroscopy with pyrene as fluorescent probe. Cationic cetyltrimethylammonium bromide (CTAB) was used as a surfactant. Native hyaluronan was used as polyelectrolyte. Hyaluronan was used in one constant molecular weight and one constant concentration. The whole system was prepared in an aqueous environment. Interactions were studied in area between critical aggregation concentration (CAC) and critical micelle concentration (CMC). The influences of the concentration of pyrene and the effect of the way of the samples preparation on aggregation behavior were also studied. It was found that above the critical aggregation concentration exists an area where stable properties of aggregates can be found. The concentration of pyrene has a major effect on the fluorescence properties of the system. Preparation of samples affects the aggregation of the system. At higher surfactant concentrations, above the stable area, was observed phase separation and gel formation.
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Development of Material Based on Hyaluronic Acid s Hydrogels for Myocardial Regeneration
Kovářová, Lenka ; Kubala,, Lukáš (referee) ; Prokš,, Vladimír (referee) ; Pekař, Miloslav (advisor)
The thesis is focused on material development based on hyaluronic acid usable in regenerative medicine, especially for heart tissue regeneration after myocardial infarction. The object of the study is the oxidized form of hyaluronic acid (HA-Ox) and hydroxyphenyl derivative of HA (HA-TA). HA-Ox can be crosslinked with a bifunctional alkoxyamine POA and HA-TA undergoes an enzymatic reaction in the presence of hydrogen peroxide catalysed by horseradish peroxidase leading to gel formation. To describe the materials, chemical and physical properties, gelation kinetics and conditions of crosslinking reactions were studied. Hydrogels were characterized by mechanical and viscoelastic properties, degradability or stability in simulated body fluids. These hydrogels serve as scaffolds for the selected cell type. To promote cell adhesion and viability, an RGD sequence has been bonded to the structure of HA-TA. This resulting material is also compatible with selected applicators. Its viscosity and extrusion force are low enough to allow application with a catheter with a very small internal diameter. The applicability of the material through the supply tube to the hydrogel reservoir of the second SPREADS device showed good homogeneity, cell distribution and viability. Finally, the material was applied in vivo using these devices during a preclinical study.
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Influence of the temperature on hydrophobic domain quality in a biopolymer-surfactant system.
Hnyluchová, Zuzana ; Kopuletá, Ema (referee) ; Mravec, Filip (advisor)
The temperature dependence on polarity has been investigated by fluorescence spectroscopy with pyrene as a probe. Pyrene was chosen thanks to its unique sensitivity to polarity of the medium. As a biopolymer was chosen 73 kDa and 1,4 MDa hyaluronic acid. Emission spectra of pyrene were measured as a function of temperature in aqous solution of CTAB in a presence and absence of sodium chloride. The results show, that the addition of specific concentration of hyaluronic acid to the sample with CTAB, mostly doesn´t have effect to change increasing/decreasing slope of polarity with the temperature.
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Influence of pH on polyectrolyte-surfactant system
Mourycová, Jana ; Omelka, Ladislav (referee) ; Pekař, Miloslav (advisor)
In this bachelor thesis, was studied influence of pH on aggregation polyelectrolyte-surfactant system using fluorescence spectroscopy and pyrene as fluorescent probe was used. As polyelectrolyte, hyaluronan with different molecular weight was used. Two surfactants cationic surfactant cetyltrimethylamonium bromide (CTAB) and nonionic surfactants polyoxyethylene (20) (TWEEN 20) were selected for interaction with hyaluronan. In the pH range from 3 to 10, no signifact changes in the aggregate non-polar core was observed. This mean system is stable against changes in the observed pH range. At system with higher concentrations of cationic surfactant (CTAB) and higher molecular weight hyaluronan occurred phase separation and gel exclusion was observed.
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Advanced Fluorescence Techniques in Research on Micellar Systems and Their Interactions with Biopolymers
Holínková, Petra ; Burgert, Ladislav (referee) ; Táborský, Petr (referee) ; Pekař, Miloslav (advisor)
The dissertation thesis deals with study of advanced steady-state and time-resolved fluorescence techniques, which can be used for study of micellar systems properties. Selected fluorescence techniques were used for characterization of Septonex and CTAB cationic micellar systems and theirs interactions with hyaluronan. Fluorescent probe pyrene was used for determination of critical micelle concentration (CMC) and micellar aggregation number of these surfactants. The changes of fluorescence behaviour of fluorescein and prodan were studied in wide concentration range of Septonex. Next chapter of thesis deals with study of Förster resonance energy transfer between perylene and fluorescein in Septonex and CTAB micellar solutions and the effect of hyaluronan addition to these systems. Also steady-state and time-resolved fluorescence anisotropy studies were used for research of the effect of hyaluronan addition to micellar solutions. The last chapter of this thesis is focused on photophysical behaviour of Prodan in different solutions (water, Septonex solutions below CMC, hyaluronan solution, Septonex micellar solution and Septonex micellar solution with hyaluronan), which was discussed on the basis of time-resolved emission spectra.
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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.
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Interaction of phospholipids with polyelectrolytes in aqueous medium
Maivaldová, Iva ; RNDr.Miroslav Gál, Ph.D. (referee) ; Klučáková, Martina (advisor)
This diploma thesis is focused on determination of aggregation behavior of selected phospholipids (lecithin; 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine) in water and on the effect of native hyaluronan addition of various molecular weights and concentrations on this behavior. The behavior has been investigated with fluorescence spectroscopy using pyrene and perylene as fluorescence probes being able to penetrate into hydrophobic cavities of formed aggregates. Critical aggregation concentration and the concentration at which lecithin begins to aggregate have been determined. Regarding 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine, it was possible to determine only the beginning of aggregation value. The values of this parameter for lecithin and for 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine correspond in the order. It has been investigated, that the addition of native hyaluronan has only in some systems slight effect on the aggregate behavior of selected phospholipids.
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Studying the quality of hydrophobic domains in the phase separated hydrogels
Burešová, Natálie ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
The thesis deals with the study of hydrophobic domains in phase separated hydrogels. Two types of polyelectrolytes (hyaluronan, dextran) and oppositely charged surfactants (carbethopendecinium bromide, sodium dodecylsulphate ) are used. Phase separated hydrogels are formed by electrostatic interactions. The target of the thesis is to study the polarity of environment in phase separated hydrogeles by fluorescence spectroscopy. Fluorescence measurements is performed by using pyrene, Nile red and laurdane as fluorescence probes. All probes are sensitive to the polarity of the environment. The results showed that probes can be expected in the polar environment of hydrogels.
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Native hyaluronan as a delivery system for hydrophobic drugs
Černá, Eva ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
The aim of this paper is to discover whether it is possible to use the native form of hyaluronic acid as a hydrophobic drug carrier for a targeted distribution in the body. In its structure, hyaluronic acid is a linear high molecular weight biopolysaccharide which is found in most living organisms. Hyaluronan is involved in many physiological processes and therefore is essential for the functionality of the human body. It is in most tissues of the human body, high concentration is in the skin, the vitreous body and is also observed in cancer cells that contain several receptors for hyaluronan. These receptors include CD44 and RHAMM. The interaction of the hyaluronic acid delivery system and the hydrophobic medicinal with these receptors could ensure a free passage for drugs to the affected tissue, where the release of the drug would destroy the affected cells. The drug would directly target the damaged tissue and did not burden the rest of the body like the cytotoxic agents do. In this paper the native form of hyaluronic acid, which we normally find in the human organism, was chosen as the carrier. Its properties do not stand above other carrier systems, but its biocompatibility and biodegradability in the body greatly exceed them. High molecular weight hyaluronic acid was used as a carrier and the hydrophobic dye sudan red G, a substance of similar properties, was used instead of a hydrophobic drug.
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Interactions between hyaluronan and cetrimide
Adamcová, Zuzana ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
Interactions between hyaluronan and cationic Cetrimide were studied using fluorescence spectroscopy and turbidimetry in model physiological solution (0,15 M NaCl) and water. Results obtained in water showed strong electrostatic interactions before reaching CMC of the surfactant, which were screened in presence of salt due to high ionic strenght of the solution. Behavior of Cetrimide-hyaluronan systems was compared with the pure TTAB in equivalent system. It was found, that changes in Cetrimide-HA system occure at lower concentrations of the surfactant than in TTAB-HA system. This was probably caused by presence of small amount of CTAB in Cetrimide.
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