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Effect of crowding agents on DNA-surfactant interaction
Sovová, Šárka ; Hurčíková, Andrea (referee) ; Pekař, Miloslav (advisor)
Tato diplomová práce se zabývá vlivem zaplňovacích činidel na interakce v systému DNA-tenzid. DNA o velikosti 4017 párů bází byla připravena polymerázovou řetězovou reakcí, jako templát byl použit plasmid pSB-E1g. Polyetylen glykol (PEG) byl použit jako zaplňovací činidlo a jeho vliv na DNA-tenzid interakce byl zkoumán experimenty založenými na fluorescenci a gelové elektroforéze. Také byl studován vliv iontové síly za použití NaBr na interakce DNA-tenzid za použití zaplňovacího činidla. Data byla vyhodnocena a evaluována v této práci. V úvahu byl brán i možný vliv polyetylen glykolu na kritickou micelarní koncentraci (CMC) tenzidu, bylo provedeno měření CMC pomocí ultrazvuku s vysokým rozlišením, avšak nebyl zjištěn žádný značný vliv zaplňovacího činidla na CMC tenzidu. Část této práce bude zahrnuta v publikaci s anglickým názvem Combined role of macromolecular crowding and cationic surfactant in efficient DNA condensation.
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Aminoclays - optimization of preparation and characterization
Plotěná, Michaela ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
The objektive of this paper is to give an overview of synthetis, properities and application of magnesium phyllosilicate with 3-aminopropyl functional groups (aminoclay). The research in this paper focuses on preparing aminoclay, specifically to prove the prescribed procedure and its modifications. The structure of the final product was verified by X-ray analysis and scanning electron microscope. The main motivation is the synthesis of aminoclay opportunities in the pharmaceutical industry. Aminoclay would serve as an adsorbent that would ensure greater bioavailability of the drug.
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Interaction of hyaluronan with surfactant CAE
Trtek, Jan ; Pekař, Miloslav (referee) ; Hurčíková, Andrea (advisor)
The diploma thesis is focused on the study of interactions between hyaluronan of various molecular weights with CAE surfactant. This surfactant does not have the exact composition and there is not known their molecular weight. One of the main parameters needed to describe the interactions between surfactant and hyaluronan, there is the determination of critical micellar concentration. The value of critical micellar concentration of CAE is not known yet. All measurements were made for solutions in aqueous solution and 0.15 M NaCl. The determination of the molecular weight of this surfactant was performed by the technique SEC-MALS-dRI. High resolution ultrasonic spectroscopy was chosen to determine the critical micellar concentration and tensiometry was chosen as a complementary method. The interactions of CAE surfactant with polysaccharide of hyaluronan were showed by high resolution ultrasonic spectroscopy and densitometry. Compressibility was calculated from ultrasonic velocity and density.
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Isolation and characterization of the soil gels
Kundera, Ondřej ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
The aim of this study are the gel-creative components in soil, mainly the isolation and characterization using electron microscopy and available analytical methods like FT-IR spectrometry, elementary and thermogravimetric analysis. The knowledge from this study may help to define function and significance of this gels to soils and nature. The theoretical part of this thesis deals with humic substances which are, according to published articles so far, expected to play an important role in the formation of the soil gels. The experimental part solves especially the optimization of the method of isolation soil gels and his further characterization.
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Structural and transport properties of hybrid hydrogels with application utilization
Zhurauliova, Darya ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with the preparation and subsequent characterization of structural and transport properties of hybrid hydrogels based on polyvinyl alcohol and sodium alginate concerning their application potential. The thesis aims to study the current state of the solved issue on the topic of characterization of structural and transport (release) properties of hybrid hydrogels about their use in various branches of human activity and also based on literature research to propose and optimize a suitable preparation procedure and to carry out a series of experiments for their characterization. With regard to the literature research, suitable polymers capable of gelation, such as polyvinyl alcohol (PVA) and natural polysaccharide – sodium alginate, were selected for the preparation of hydrogels. The preparation of this hybrid network involved the physical cross-linking of PVA by freezing and thawing and ionic cross-linking of sodium alginate with calcium ions. By combining these polymers, viscoelastic, swelling and transport properties were determined by using physicochemical methods. Rheological measurements were performed to study the mechanical properties - specifically oscillation and amplitude tests. The structural properties of hydrogels (or xerogels) were determined, by scanning electron microscopy. The transport (release) properties of gel systems were determined by diffusion experiments with the UV-VIS spectrometry detection method, in which an organic dye (methylene blue) was used as a model probe. Another aim of this diploma thesis is to modify the internal structure of hybrid hydrogels with suitable reagents, ie., lecithin. The presence of lecithin in the hybrid hydrogel three-dimensional network serves as a model of the phospholipid bilayer, forming the cell membrane or occurring in tissues, and thus has a significant effect on rheological and transport properties. Physicochemical methods also determined the mechanical, swelling and transport properties of hybrid hydrogels with the addition of lecithin. The conclusion of this work is a summary of measured data to provide a comprehensive overview of this issue. The results suggest that the presence of sodium alginate in the PVA structure reduces the mechanical properties, although the presence of lecithin increases the strength of the hybrid hydrogels. However, by comparing all measurement results, it is possible to determine that sodium alginate, resp. lecithin affects the properties and structure of the hydrogel, which makes it possible to correct the properties of hybrid gel systems according to the required applications.
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Influence of the preparing of a biopolymer-surfactant system on its aggregation behavior.
Pilgrová, Tereza ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
To study the effect of the method of preparation of biopolymer-surfactant on the aggregation properties several experiments were designed. Closer investigation was made on native hyaluronan-cetyltrimethylammonium bromide (CTAB) system. The system has been studied in the phosphate buffer in aqueous and saline solutions. The effect of the order of substances addition in the samples, the influence of different methods of preparation of certain concentrations of the solutions or the effect of dissolving powdered biopolymer and surfactant on the contrary, the resulting system were investigated. Fluorescence intensity was measured for all prepared samples and its changes were investigated. Pyrene and Nile red were used as fluorescent probes. Some samples were also measured by tensiometer. Measurement of surface tension was based on the method of divorcing the ring from the surface. It was found that the order of the mixing of solutions has a significant effect on the aggregation properties of the system and its appearance. Further effects were detected on the prepared samples by dissolving powdered biopolymer surfactants and vice versa, and environmental influences of the polarity of the system. It was found that sodium chloride abolished the effects of interactions in the system. Effect of method of preparation of certain concentration of CTAB in phosphate buffer is reflected only slightly.
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Modelling of particle thermal motion
Orság, Miroslav ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
The goal of this thesis was to get familiar with the basics of mathematical description of the thermal motion of particles in a given media, and with other possibilities of the software package COMSOL Multiphysics. A model for viscous and viscoelastic environments was created, a uniform and user friendly system for simulation and calculation of MSD and system for data conversion from FCS to MSD. Furthermore, the possibilities of the model for use in microrheology were assessed and another procedure in the implementation of the COMSOL program in the characterization of gels was proposed.
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Study on the Supramolecular Structure of Humic Acids
Širůček, David ; Pekař, Miloslav (referee) ; Kalina, Michal (advisor)
This bachelor thesis is focused on the study of supramolecular structure of humic acids. This issue was studied on a number of HA samples which differed in source matrix (lignite, leonardite, soil, peat and compost). For these purposes, methods of size exclusion chromatography, dynamic and electrophoretic light scattering and UV-VIS spektrometry were used. In order to better understand the formation of the supramolecular structure of HA, the ways of its stabilization and how it was influenced by the change in pH, individual HA samples were studied in three pH-varying mediums (3,5; 7 and 12). The results obtained on a wide range of used humic acids are in accordance with the supramolecular theory of the structure of humic acids in aqueous solutions which describes them as freely-bound supramolecular associates of relatively small molecules having both polar and nonpolar parts and can be formed into more complex supramolecular aggregates depending on the conditions in the solution (pH, content of low molecular weight ions, etc.).
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Ultrasound phantoms in medical diagnostics
Koňaříková, Anna ; Pekař, Miloslav (referee) ; Hurčíková, Andrea (advisor)
This bachelor’s thesis studied the relative ultrasonic velocity of gel matrices made of gelatine, agar or agarose depending on concentration and time. These properties have been studied both in the air and water environments, using high resolution ultrasonic spectroscopy. In additon, the basic properties of gel matrices, such as desiccation or moulding, were observed. Relative ultrasonic speed has been found to grow linearly with sample concentration and its changes over time are minimal. Basic gel matrices without added preservatives are able to withstand the usable state only for a week.
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Time-Resolved Fluorescence in Research of Hyaluronan-Colloidal Systems Interactions
Mondek, Jakub ; Táborský, Petr (referee) ; Peter, Kapusta (referee) ; Pekař, Miloslav (advisor)
The aim of the doctoral thesis was to study advanced fluorescence techniques and its use in colloids or hyaluronan-surfactant systems and hydrogels based on hyaluronan, respectively. Steady-state and time-resolved fluorescence were used to study excited state proton transfer fluroescen probes in hyaluronan-surfactant systems to asses the influence of hyaluronan hydration to its interactions with oppositely charged surfactants. Firstly, different excited state proton transfer fluorescence probes were discussed to choose the most suitable candidate for next research. The influence of hyaluronan on inner environment of micells was determined based on the sensitivity of excited state proton transfer of chosen fluorescence probe 1-naphtol and, based on above mentioned experiments, the structure of hyaluronan hydration shell was discussed. The next part of doctoral thesis was focused on fluorescence lifetime correlation spectroscopy and on the development of method of nanorheology. Measured correlation functions were transformed to mean square displacement with developed MATLAB script. Firstly, the fluorescence method was compared with well described methods such as videomicrorheology and dynamic light scattering to asses the reliability of fluorescence correlation spectroscopy in microrheology. Secondly, nanorheology method was developed and its use in passive nanorheology of hyaluronan hydrogels was discussed. Based on mentioned experiments, the fluorescence correlation spectroscopy microrheology and nanorheology methods were optimized to use the methods in hydrogel research.
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