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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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Hydrogels with carbon fibers
Kučerová, Barbora ; Bouška,, Marek (referee) ; Pekař, Miloslav (advisor)
This diploma thesis is focused on the study of the behaviour of carbon fibers in the hydrogel, especially the viscoelastic modules od these gels ort he coefficient of color transmission through the gel. The main goals were to optimize the samples and measure their viscoelastic modules on a rheometer, in several different modes. This was followed by simulation of physiological conditions for selected samples and their measurement on the rheometer. There was also an experiment of continuous diffusion in cuvettes, in which the penetration of the dye through the gel with the addition of fibers and for comparison also without them. Last but not least diffusion pairs were prepared.
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Ultrasonic and Densitometric Characterization of Hyaluronan and its Interaction with Surfactant
Hurčíková, Andrea ; Hrdina, Radim (referee) ; Mráček,, Aleš (referee) ; Pekař, Miloslav (advisor)
This disertation thesis is focused on the study of physico-chemical interactions of hyaluronan (with molecular weights from 10 to 1750 kDa) with cationic surfactants measured using uncommon technique named high resolution ultrasonic spectroscopy. Densitometer was also used for the study of these interactions, in measuring of density and ultrasonic velocity of hyaluronan with different molecular weight in dependence on elevated temperature (25 50 °C). The aim is the determination of critical micelle concentration (CMC) and critical aggregation concentration (CAC) of the suractants in the absence and in the presence of hyaluronan with various molecular weights. Interactions in this system are important for the design of the systems for the targeted delivery, especially for the drugs. The experiments were made in water and sodium chloride solution. The significant breakpoint in the ultrasonic velocity showed changes in the system hyaluronan-surfactant.
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Dynamic tensiometry of biocolloids
Kulilová, Pavlína ; Mašek, David (referee) ; Pekař, Miloslav (advisor)
Hyaluronová kyselina je v současné době velmi významná biomolekula používaná v medicíně a kosmetice, a její výzkum je důležitý pro další budoucí použití. Zaměření této práce je studování povrchových vlastností hyaluronové kyseliny, jejích hydrofobních derivátů a roztoků SDS pro srovnání, za použití tenziometrie. Tyto sloučeniny byly zkoumány ve vodě a v roztocích ve formě sodné soli. Sledované vzorky byly měřeny dvěmi metodami v různých koncentračních rozmezích při laboratorní teplotě pomocí nového BPA-800P bublinového tenziometeru. Byly navrženy takové experimenty, aby se zjistily využitelné možnosti tohoto přístroje pro další výzkum. Výsledky práce ukazují rozdílnosti jednotlivých povrchově aktivních látek v závislosti na jejich koncentraci a použitém prostředí. Hyaluronová kyselina nevykazuje povrchovou aktivitu, zatímco její deriváty a SDS ano.
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Production of Selected Microbial Metabolites and Energy Using Different Waste Materials
Petrik, Siniša ; Rychtera, Mojmír (referee) ; Němec, Miroslav (referee) ; Pekař, Miloslav (referee) ; Márová, Ivana (advisor)
Pro zpracování a nakládání s odpadními substráty lze použít řadu postupů a možností. Stále se rozšiřující spektrum metod a technologií umožňuje další využití materiálů a energie ve formě obnovitelných zdrojů. Jedním z řešení pro zpětné získávání některých odpadních materiálů je využití tzv. bílé (průmyslové) biotechnologie, která zahrnuje praktickou aplikaci metabolických aktivit celé řady různých mikroorganizmů včetně jejich specifických biologických drah k produkci látek s vysokou přidanou hodnotou. V předložené práci screeningového typu bylo pro zhodnocení odpadních surovin využito několik druhů mikroorganizmů kultivovaných za různých specifických podmínek včetně kultivace na odpadních materiálech získaných zejména ze zemědělství a potravinářství. Cílem bylo získání vybraných typů průmyslově cenných metabolitů, případně energie. Předložená studie byla zaměřena na srovnání růstu a produkčních vlastností několika kmenů karotenogenních kvasinek rodu Rhodotorula, Sporobolomyces a Cystofilobasidium, kultivovaných v médiích s obsahem glycerolu (technický a odpadní glycerol), dále v médiích obsahujících pšeničnou slámu, hydrolyzovanou slámu zpracovanou v hydrotermálním procesu při vysoké teplotě a zbytky po filtraci hydrolyzátu. Dalším testovaným odpadním substrátem byla syrovátka. Všechny testované kvasinky byly schopny využít glycerol jako jediný zdroj uhlíku. Produkce biomasy při kultivaci na technickém glycerolu se více či méně přibližovala kontrole (cca 7 - 10 gl-1), zatímco při kultivaci na odpadním glycerolu byla produkce vyšší (10.9 - 14.5 gl-1). Produkce karotenoidů a ergosterolu byla vyšší v glukózovém médiu než v médiu s obsahem glycerolu. Všechny testované kvasinky byly rovněž schopny produkovat neutrální lipidy, a to v rozmezí 11 - 15 %, s výjimkou C. capitatum, kde produkce dosahovala více než 22 % obsahu neutrálních lipidů. Pšeničná sláma a produkty z ní připravené se ukázaly být využitelnými substráty s vysokým potenciálem pro produkci biomasy i metabolitů, a to zejména u kmene S. roseus. Syrovátka, jako odpadní produkt mlékarenství, byla účinně využita jako substrát pro kokultivaci karotenogenních kvasinek a bakterií mléčného kvašení. Kokultivační proces může vyvolat nadprodukci pigmentů a ergosterolu, přičemž získaná biomasa díky obohacení o bakterie L. casei dosahovala vyšší kvality. Za účelem energetického využití mikrobiálního metabolismu formou mikrobiálních palivových článků, tzv. „Microbial Fuel Cell“ byla aplikována směsná kultura bakterií získaných z čistírny odpadních vod. Tyto mikroorganizmy hrají významnou roli při výrobě elektrické energie a současně také při čištění odpadních vod. Elektřina je generována přímo z organických látek přítomných v kultivačním médiu a lze ji použít pro provoz čistírny samotné a případně i pro další aplikace.
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Optimization of the Preparation of Thin Hydrogel Layers Based on Biocompatible Polymers
Vacková, Barbora ; Pekař, Miloslav (referee) ; Kalina, Michal (advisor)
The aim of this master thesis deals with the optimization of the preparation of thin hydrogel films based on polyvinyl alcohol (PVA) with the possibility of incorporating suitable additives (polyelectrolytes, plasticizers, etc.) into the structure of the prepared film to modify its properties. DEAE-Dextran hydrochloride and polyglutamic acid (PGA) were used as polyelectrolytes. The basic characterization of the properties was performed on modified films, which were compared with pure PVA films. The films were characterized by thickness, swelling ability, barrier properties, tensile properties, specific surface area, antimicrobial tests, and thermogravimetric analysis. The swelling ability of PVA/PGA films was very high, which may be a disadvantage for their use in the packaging industry. Swelling increases the amount of water in the matrix of the PVA film, what leads to a higher growth of microorganisms and to degradation of thin film. The water vapor transmission rate was greatly affected by the addition of a plasticizer. The small specific surface area of the films indicates a smooth surface that promotes good barrier properties. Films with the addition of a plasticizer showed relatively good mechanical properties. The values of tensile strength, elongation and elastic modulus were comparable to commercially available films such as polypropylene (PP) or polyethylene (PE). Based on all experiments, PVA, PVA/DEAEDextran films and their variants with the addition of glycerol as a plasticizer were evaluated as the best candidates for the use of these films as packaging materials. The follow-up work could be dealing with the optimization of PVA films for oxygen permeability. Furthermore, the possibilities of using these films in the packaging industry based on the relative humidity of the environment, could be defined as other interesting area of future research.
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