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Hydrogels based on microemulsions and polyelectrolytes
Růžičková, Kristýna ; Kalina, Michal (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with preparation and characterization of microemulsion based phase separated hydrogels while using low molecular weight and high molecular weight hyaluronan. Microemulsions were prepared from canola oil, sunflower oil, lemon oil and tea tree oil. As a dye for studies of behaviour of hydrogels was used Oil red O which simulates hydrophobic drug. The main part of this thesis studies the release of this dye from hydrogels by using UV-VIS spectroscopy. The content of the dye in hydrogels was monitored after 24, 48 and 72 hours. Based on measured data we can state that hydrogel prepared from low molecular weight hyaluronan release bigger amount of the dye than hydrogel from high molecular weight hyaluronan. Based on measured data after 72 hours we can say that hydrogel from microemulsion with tea tree oil and hydrogel from microemulsion with lemon oil released bigger amount of the dye than hydrogel without microemulsion. Another advantage of these two hydrogels is increased thougness. Content of sunflower and canola oil indicated rather negative influence on behaviour of hydrogels.
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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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New Methods of Cross-linking of Humic Substances
Lepíková, Jana ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
This bachelor thesis was focused on the study of crosslinking of humic substances. The main aim of this work was to find and optimize utilization of new crosslinking agents for humic acids. Commercial product – lignohumate – was also used in the work as comparative sample. Two groups of crosslinking agents were studied in this work – multivalent metals (CaCl2, MgCl2) and citric acid. In all cases the studied hydrogels were cross-linked by means of chemical valences. All prepared hydrogels were characterized using the determination of their inner pH, density and concent of dry matter. The process of aging of hydrogels – syneresis – was also studied. The main experimental method applied for hydrogels characterization was rheology. Prepared hydrogels represent interesting materials for following studies and also for possible future practical applications.
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Activation of biochar from wheat bran
Sauchanka, Katsiaryna ; Kalina, Michal (referee) ; Pořízka, Jaromír (advisor)
This graduation work is devoted to the issue of biochar production from wheat bran and ways of its surface activation. The theoretical part summarizes information about biochar, its physico-chemical properties, production methods and surface modification options. It also contains description of EBC certificate, that sets requirements for biochar which is placed on the market. The practical part of the work focuses on activating of the biochar surface and comparing the results with the available literature and European biochar certificate.
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Preparation and Characterization of Drug Carrier Systems on the Basis of Magnetic Nanoparticles
Chvátalová, Barbora ; Burdíková, Jana (referee) ; Kalina, Michal (advisor)
This bachelor thesis deals with the study of magnetic nanoparticles, optimizing their preparation and stabilization. The nanoparticles with different ratios of Fe2+ and Fe3+ ions were prepared by coprecipitation by variously concentrated sodium hydroxide. Three samples of particles were selected and were further observed. Their stability in Milli-Q water, buffer, polyvinylalcohol, hyaluronic acid and chitosan was studied in function of time using methods of dynamic and electrophoretic light scattering. By UV-VIS spectrometry it was confirmed that the magnetic nanoparticles were actually prepared. Nanoparticles coated with chitosan and hyaluronic acid were then further characterized using FT-IR, XRD and SEM.
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Influence of the Application of Lignite on the Distribution of Organic Carbon in Soil
Širůček, David ; Záhora, Jaroslav (referee) ; Kalina, Michal (advisor)
This diploma thesis is focused on optimization of sequential chemical fractionation method to humeomics in order to be useful for determination of organic matter content and distribution and also organic elements in soil. Subsequently, the optimized method is used to assess the efect of lignite application as soil support on these soil characteristics. For these purposes, there were three source matrices of organic matter (lignite, soil and annual soil extraction after lignite application) fractionated by sequential chemical analysis. In parallel, these samples were also fractionated by classic alkaline extraction to obtain the so-called extractable fraction of organic matter (NOM). Individual fractions from sequential chemical fractionation as well as NOM samples were characterized by methods of elemental analysis (determination of organic elements), thermogravimetry (contents of ash, organic matter and moisture) and FTIR spektrometry (structural analysis). The results obtained from a large range of data from all humeomics fractions and NOM fractions showed that the method of sequential chemical fractionation gives higher yields of organic matter compared to classic alkaline extraction. Another indisputable advantage is the fact that the obtained fractions divided according to solubility and strenght of binding to soil inorganics can be better characterized by physical-chemical methods, which provides more detailed information about soil organic matter. The results of the work also show that in order for lignite as a support substance to significantly affect soil properties, a longer time, multiple sampling and repetition of individual fractionations would be needed.
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Transport of phamaceuticals in reactive hydrogels
Kotradyová, Viktória ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
The bachelor thesis focuses on a problem associated with diffusion processes of antibiotics in agarose hydrogels enriched with humic acids. The soil model system simulates the transport of these pollutants and demonstrates the ability of the humic acids to bind and retain these substances, thereby preventing their subsequent contamination at unintentional places. The theoretical section encompasses an overview of the occurrence of pharmaceuticals in soil and water systems; it also provides information about their behaviour, effects, degradation, and potential outcomes in nature. It further clarifies basic knowledge of soil components, in particular humic acids. Furthermore, the mechanism behind the diffusion processes is explicated. Within the experimental part, the diffusion of the sulfomethoxazole and sulfapyridine in two types of agarose hydrogels was examined. Firstly, the pure agarose hydrogel was used and secondly, the addition of the active agent in the form of humic acids was performed. The method of diffusion from continuous source was utilized, followed by measuring through UV-VIS spectrometry for 21 days. The study aimed to compare the results and to establish the diffusion coefficients of the pharmaceuticals in both types of hydrogels.
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Use of copolymer polyhydroxyalkanoates in development of intelligent packaging
Kreuzerová, Monika ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the preparation and characterization of copolymers P(3HB-co-4HB). The theoretical part discusses polyhydroxyalcanolates (PHA), where their structure, properties and synthesis are described and subsequently the selected copolymers, which contain monomeric units 3HB, are listed. Furthermore, the review part is processed for the current state of the issue, which states the use of copolymers PHA and current research work on the incorporation of active substances into copolymers. The aim of this work was to characterize and compare the created P(3HB) and P(3HB-co-4HB) foils with a 4HB monomeric unit of 65,25 % and 43,61 % and subsequently determine the potential of foil usability as intelligent packaging materials. First, PHA were subjected to gas chromatography, SEC-MALS, FTIR and DSC analysis. In the second part of the thesis, the permeability of foils to water vapor and the release of model active substances from PHA foils was studied. For this purpose, two active substances (curcumin and salicylic acid) were selected, which were incorporated into a film of homopolymer P(3HB) and two copolymers with a proportion of 4HB of 65,25 % and 43,61 %. In foils prepared from copolymers, the active substances diffusion was faster than in P(3HB). Within the copolymers, P(3HB-co-43,61%4HB) released substances at a higher speed, due to the greater crystallinity of a copolymer containing 65,25 % 4HB.
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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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Study on the Effect of Biochar Application on Organic Matter in Soil
Kurková, Marie ; Sovová, Šárka (referee) ; Kalina, Michal (advisor)
This bachelor thesis studies the effect of the application of biochar on the composition of organic matter of two different soil samples. Specifically, the total content of organic matter in the soil and the ratio of humic and fulvic acids in these soils before and after the application of biochar were monitored. The composition of the soil mass was also observed thermogravimetrically and by using the certified method of humic and fulvic acids isolation from samples of studied soils. Furthermore, the effect of biochar on the growth of a model plant (maize – Zea mays) was observed. From this point of view, differences in plant growth were possible to observe from the beginning of the experiment, both in comparison with samples with and without biochar and in comparison with samples containing different doses of biochar. The type of soil used for cultivation experiments also influenced on plant growth.
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