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The behavior of superabsorbent polymers in artificial soils
Männlová, Adriana ; Smilek, Jiří (referee) ; Kratochvílová, Romana (advisor)
This bachelor thesis deals with the study of superabsorbent polymers for environmental and agricultural applications. Generally thessis preparations are to perform the funciton of irrigation ,so that thanks to its unique properties , can absorb water in tha rainy season and keep it arend the root system as long as possible. Superabsorbent polymers can also perform the fiction of fertilizer carries and thus ensure its gradual release. These gel structures were subjected to testing of their swelling in environments with different ionic strenght. Subsequently, in the long term monitored thein ability to trap water in the soil environment model.
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DLS microrheology to study gelation of polymer
Píšová, Denisa ; Smilek, Jiří (referee) ; Hnyluchová, Zuzana (advisor)
This bachelor thesis deals with the study of gelation process on model polymer through DLS microrheology. As the model polymer was used agarose and for microrheological measurement were used polystyrene particles. Agarose samples of various mass concentrations were studied through dynamic light scattering. Measured data were used to create graphs of MSD against time which were compared to MSD curves and error bars. The values of diffusion coefficients for all samples and each temperature were also compared.
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Study of barrier and transport properties of polyelectrolytes using diffusion techniques in hydrogels
Valentová, Kristýna ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
This diploma thesis was focused on study of barrier and transport properties of selected polyelectrolytes in hydrogel matrices by using diffusion techniques. The study of these properties was performed in horizontal diffusion cells where is observed the change in diffusion probe concentration over time. Diffusion experiments were performed on an agarose hydrogel with the addition of alginate, hyaluronic acid, polystyrene sulfonate, humic acids and as a model probe rhodamine 6G was used. Important parts of this thesis are also the methods which characterize the substances and hydrogel matrices such as rheology and potentiometric titration. The main aim of this diploma thesis was to investigate the effect of interactions between passing model dye (rhodamine 6G) and the appropriate gel (agarose + polyelectrolyte) on the fundamental diffusion parameters (effective diffusion coefficient, lag time, etc.).
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Study on Reactivity of Cationic Biopolymer by Simple Diffusion Techniques
Tesařová, Barbora ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
This bachelor thesis is focused on study of chitosan reactivity by simple diffusion processes realized in hydrogel media based on agarose. Mechanical properties studied by oscilatory measurements and the pore size were determined at agarose gels with the addition of chitosan as the main parameters influenced the transport properties. The main goal of this work is the investigation the reactivity of chitosan. Agarose is used only as a supporting matrix for the formation of a hydrogel. The state of the art is aimed primarily on the study of chitosan reactivity based on already published scientific papers.
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Polysaccharide-protein gels
Hájovská, Pavla ; Smilek, Jiří (referee) ; Chytil, Martin (advisor)
This bachelor thesis deals with gelation of albumin solutions and mixed solutions of albumin and the high molecular weight hyaluronic acid due to heating. Study was carried out by measuring rheological properties of the solutions, formed gels and gelation process. For the protein samples in water, the effect of concentration, ionic strength and pH were tested. For mixed solutions, the effect of concentration and a composition of the polymeric component were tested. With increasing concentration of the polymeric component, the gel point is shifted towards lower temperature values, with the concentration difference of 2 % (w/v) up to 5°C. The resulting gels exhibit higher values of loss and storage moduli. Similar behavior was observed also in the samples influenced by the ionic strength as, a result of alternation of the electrostatic interactions between the charged groups of the polymer chains and as a result of change of this charge due to the pH reduced below the pI value of the protein.
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Hydrogel phantoms for ultrasound diagnostics
Cerevatova, Kristina ; Smilek, Jiří (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis deals with properties and preparation of hydrogel phantoms used in ultrasound diagnostics. The main object of this work was to get acquainted with the production and problems of phantom models. The theoretical part of the thesis focuses on phantom characterization, the principle of ultrasound, and phantom manufacturing companies. The practical part focuses on production of phantom models in Dansk Fantom Service, and on own production in the laboratory. Then on these phantoms was studied the speed of ultrasound, attenuation, and other physical changes.
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The Study of Aggregation of Humic Acids in Different Xenobiotic Environments
Hronová, Aneta ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
Theme of the presented bachelor thesis is the study of the aggregation behavior of the humic acids (HA) in the environment of extraneous substances. As extraneous substances, three cationic surfactants were selected (CTAB, TTAB and Septonex). In the experimental part of the thesis, the humic acids were characterized in detail using different methods (elemental analysis, ash content determination, titration acidity determination). The experimental part of the thesis is dealing with the structure of created HA-surfactant systems. These systems were characterized using the results of the elemental analysis and FT-IR spectroscopy. The key part of the experimental part of the study is represented by the selection of proper methods and by determination of the critical aggregation concentration of the humic acids in the surfactant environment. For these purposes, two key methods were selected in the frame of the presented bachelor thesis: isothermal titration calorimetry and dynamic light scattering. The first method is sensitive owing to the energetic fluctuations, in the case of the dynamic light scattering we are able to detect well the changes in the particle size caused by mutual interactions of particular substances in the system.
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Hyaluronic gels for control release of active substances
Hekrlová, Veronika ; Smilek, Jiří (referee) ; Klučáková, Martina (advisor)
This diploma thesis is focused on the development of materials based on oxidized hyaluronic acid derivative (HA-Ox) crosslinked using bifunctional alkoxyamine POA. Hydrogels have been studied as potential matrices for the controlled release of biological drugs. For this purpose, hydrogels containing bovine serum albumin (BSA) as model of the active substances were prepared. The properties of the hydrogels were affected by the concentration of the derivative (10 mg / ml, 20 mg / ml and 30 mg / ml). In the first part of the work, the viscoelastic properties, swelling and dry matter content of the prepared hydrogels were evaluated. The dry matter of the starting hyaluronan derivative and the weight of the polymer network in the hydrogels were determined gravimetrically and by TGA (in all cases about 80% w/w). The difference in weight of the polymer contained in the hydrogels before and after swelling showed that the non-crosslinked sol leaches out of the hydrogel during swelling (about 10-20% w/w). Due to this phenomenon, hydrogels with a concentration of 10 mg / ml are depleted of hydrogels, while their more concentrated analogues swell even after the sol has washed off. The sizes of elastic moduli needed to calculate the mesh of the polymer network were determined using rheological measurements (amplitude and frequency test). The mesh size of the polymer network itself is calculated using two commonly used theories: Equilibrium SwellingTheory (EST) and Rubber Elasticity Theory (RET). The mesh size of BSA-free gels with a derivative concentration of 10 to 30 mg/ml was determined according to EST to 347 ± 29 nm, 319 ± 15 nm, 295 ± 6 nm and according to RET345 ± 30 nm, 308 ± 14 nm, 268 ± 5 nm. For hydrogels with BSA, the mesh sizes of the polymer network were determined according to EST 373 ± 34 nm, 307 ± 11 nm, 281 ± 7 nm and according to RET 372 ± 32 nm, 297 ± 11 nm, 258 ± 6 nm. The mesh size of the polymer network decreases with higher derivative concentration. In the second part of the work, the release of the model active substance BSA was monitored spectrophotometrically using fluorescent labeling. Using the Korsmeyer-Peppas model, it was found that diffusion release is the primary mechanism.
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Targeted modification of transport and structural properties of biomedical hydrogels
Bayerová, Zuzana ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with a targeted modification of the structural properties of hydrogels, which is closely related to the application properties of these materials (eg transport). Due to the desired pharmacological applications of the use of these materials for targeted drug release, hydrogels based on chitosan and polyvinyl alcohol as substances with good biocompatibility were selected for the study. The combination of these polymers ensured swelling (controlled by the presence of chitosan) and viscoelastic (influenced by the presence of polyvinyl alcohol) properties, which were characterized by a wide range of analytical and physicochemical methods (swelling, tensile strength, rheology, atomic force microscopy or specific surface area, etc.). Information on structural properties played a crucial role not only for a detailed description of the studied materials in terms of whether the structural properties can be changed in a targeted manner, but also served as an explanation for the different release of the active substance diclofenac from the hydrogel matrix. With regard to the literature search, the effect of pH and crosslinking was chosen to modify the properties. From the measured results it was found that even a slight change in pH has an effect on the transport or release of the active substance. The results obtained in this work may be useful in the formation of hydrogel matrices with drugs depending on the intended medical applications.
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Transport Properties of Thin Films Based on Polyvinylalcohol
Blažková, Dominika ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This bachelor thesis deals with the optimization of the preparation of hydrogel thin films based on polyvinyl alcohol (PVA). The first step was to optimize the preparation of films. PVA, with a molecular weight of 130 kDa, was used for the preparation of films and 10 wt.% solutions in ultrapure water were prepared from it. The heating duration time of the solution was set at 1.5 h at 90 °C. This was followed by drying at 50 °C for 24 h. Subsequently, PVA films were also prepared from solutions of methylene blue in water and from solutions of methylene blue in an aqueous NaCl solution. The prepared films were subsequently characterized by measuring their thickness, swelling ability, specific surface area and diffusion properties. The morphology of the PVA films was also visualized by SEM microscopy. All prepared films were smooth and had a very small specific surface area. The transport properties were monitored by the method of release into solution and Methylene blue was used as a probe. Release into 5, 10 and 20 ml of ultrapure water was observed. The results obtained show that the most methylene blue was released into the solution with the greatest volume and the release of methylene blue from the PVA film takes place freely without significant interaction with the matrix of the PVA film.
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