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Analysis of biodegradable polymers in soils
Paluchová, Natálie ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Currently, there is a growing interest in usage of biodegradable polymers, regardless of their possible risk of generation of residues. The methods that are used for determination of residues usually include pre-treatment and are expensive and time consuming. Therefore, this bachelor thesis focuses on the development and verification of analytical method that would identify and quantify of biodegradable polymer residues in soils to eliminate the problems arising from sample pre-treatment. Therefore, thermogravimetry, which appears to satisfy the above conditions, was used for the analysis. The area of polymer degradation in three types of soils during thermal oxidation and the effect of polymer on soil during the analysis was investigated. Poly(3 hydroxybutyrate) was chosen to be the representative biodegradable polymer and there were two approaches used to its detection and quatification. The methods were tested for 6 concentrations of poly(3–hydroxybutyrate) (0,1; 0,5; 1; 2; 3; 5 %). The first approach concentrated on the usage of polymer analysis in the presence of a blank (without contaminat), which was subtracted from the blank. Using this method, the temperature interval of polymer degradation and weigh loss changes in this interval were observed. The second method focused on a soil universal model, that allows the identification and quatification of samples when the blank is not present. The blank is simulated by 19 equations, that allow the identification of intervals, in which degradation of samples occurs and also it provides the possibility to determinate the type of the polymer. However, the principle component analysis indicated that the method is sensitive to the type of soil and therefore it needs adjustments. Samples were incubated for 4 months, to verify the sensitivity of the method, in case of partial or complete decomposition of samples by soil microorganisms,. Thereafter, the concentrations of poly(3-hydroxybutryrate) in soil determined by respirometry and thermogravimetry were compared. The results indicated that accelerated degradation caused by poly(3-hydroxybutrylate) or contamination of the sample with the surrounding atmosphere during respiration may have occurred. Residual poly(3–hydroxybutyrate) was thermogravimetrically verified and results were compared to respirometry. According to the results it can be observed that there was an interaction between the soil organic matter and biota or contamination of the sample with the surrounding atmosphere. The results revealed, that there is a possibility of determination of biodegradable polymers in soils by thermogravimetric analysis. There are good results using the blank method, but it is limited by the existence of a blank. The method that is using the soil universal model (without blank) has a great potential in the future, but adjustments still need to be done.
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Biocomposites based on polyhydroxybutyrate for 3D printing
Horálek, Matyáš ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
The submitted diploma thesis deals with preparation and characterization of biocomposite based on poly-3-hydroxybutyrate. Biocomposites were fabricated with respect to later use in 3D printing. The methodology for testing different kinds of materials and their suitability for 3D printing as well as evaluation of mechanical and thermal properties was established. The first part of this work was focused on the experiments with print temperature and the material flow rate and its influence on the look of 3D printed object and on the material tendency to warp during 3D printing. The design of the experiment method was used for the analyzing of obtained data. It was proven that the amount of kaolin and tributyl citrate has positive influence in reducing warping. By optimization of the biocomposite recipe it was achieved improvement in tensile modulus of elasticticity, ductility, tensile strength, notched and unnotched toughness.
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Evaluation of the effects of biodegradable microplastics on biota of freshwater ecosystem via ecotoxicity tests
Procházková, Petra ; Maršálek,, Blahoslav (referee) ; Beklová, Miroslava (referee) ; Zlámalová Gargošová, Helena (advisor)
Microplastics, which are ubiquitous contaminants of freshwater ecosystems, have raised concerns regarding their potential impact on the environment. For this reason, there is an effort to replace conventional plastics with biodegradable alternatives that can easily degrade in the environment. However, the process of biodegradation of these materials requires specific conditions, such as temperature, humidity, pH, and the presence of microorganisms, which are not always met adequately. Consequently, they may fragment and form biodegradable microplastics that can affect the environment similarly to conventional microplastics. Therefore, the aim of this study was to assess the impact of microplastics of biodegradable poly(3-hydroxybutyrate) microplastics on freshwater organisms, specifically the alga Desmodesmus subspicatus, the plant Lemna minor and the crustacean Daphnia magna. Additionally, we aimed to develop a suitable analytical method for the direct detection of microplastics in the body of D. magna. Although the observed effects were not always significant, they highlighted certain secondary problems that may arise due to the presence of biodegradable microplastics in the environment These issues could be related to biodegradability and the formation of biofilm on the surface of biodegradable microplastics, leading to subsequent nutrient depletion in the surrounding environment. Therefore, the use of biodegradable plastics as a substitute for conventional materials must be approached critically.
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Preparation of Poly(3-hydroxybutyrate) based acrylic monomer
Liška, Marek ; Přikryl, Radek (referee) ; Figalla, Silvestr (advisor)
The main aim of this thesis is to research and prepare acrylic (methacrylic) monomers derived from poly(3-hydroxybutyrate). The monomers were prepared in two-step syntheses. In the first step P3HB was depolymerised with selected alcohols and afterwards, products of those syntheses were used as substrate and mixed with polymethylmethacrylate to produce their methacrylic derivates. The selected alcohols for the alcoholysis were ethanol and ethylene glycol. In total, four substances were prepared. Products of alcoholysis were ethyl-3- hydroxybutyrate, 2-hydroxyethyl-3-hydroxybutyrate and their methacrylic derivates. Significant part of this thesis is aimed towards the analysis of prepared substances and the analysis of reactions. In the process, titrations and instrumental methods, such as gel permeation chromatography (GPC), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetry (TGA) and differential scanning calorimetry (DSC) were used. This work describes preparation and analysis of polymers prepared from methacrylates from the mentioned syntheses. Cross-linked polymers, because of their low glass-transition temperature are elastomers.
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Poly(3-hydroxybutyrate) based materials for 3D printing in medical applications
Krobot, Štěpán ; Vojtová, Lucy (referee) ; Přikryl, Radek (advisor)
Tato diplomová práce se zabývá přípravou a testováním 3D tištěných skafoldů pro kostní tkáňové inženýrství. Cílem práce je laboratorní příprava polymerních směsí na bázi poly(3-hydroxybutyrátu), polymléčné kyseliny a polykaprolaktonu a jejich zpracování do podoby 3D tiskových strun. Byly připraveny tři polymerní směsi, které byly zpracovány do podoby 3D tiskových strun. Pro vyhodnocení termických vlastností byla provedena diferenciální skenovací kalorimetrie, následně teplotní věžový test a test „warpingu“ pro stanovení zpracovatelských podmínek při 3D tisku. Nejnižší naměřený „warping“ koeficient byl 1,26 u směsi poly(3-hydroxybutyrátu) s polykaprolaktonem a změkčovadlem. Ke studiu mechanických vlastností materiálů byla použita tahová zkouška, tříbodová ohybová zkouška a tlaková zkouška. Skafoldy s různými povrchy pro kostní tkáňové inženýrství byly 3D tisknuty z připravených strun s cílem určit nejoptimálnější povrch pro proliferaci buněk. Pro stanovení povrchových vlastností a jejich vlivu na adhezi buněk bylo provedeno měření optického kontaktního úhlu s využitím metody OWRK pro výpočet povrchové energie. 3D vytištěné povrchy byly také podrobeny analýze drsnosti pomocí konfokálního mikroskopu, aby byla určena jejich drsnost a její vliv na kontaktní úhel s vodou a růst buněk. Nakonec v poslední části byly ve spolupráci s Ústavem experimentální medicíny AV ČR provedeny in vitro testy na skafoldech s cílem zjistit, zda jsou připravené materiály necytotoxické, a jak povrch skafoldu ovlivňuje růst a proliferaci buněk. Bylo zjištěno, že dva ze tří materiálů nejsou cytotoxické (obě směsi poly(3-hydroxybutyrátu) s polykaprolaktonem) a že jejich mechanické vlastnosti jsou srovnatelné s lidskou trabekulární kostí. Nejoptimálnějším povrchem pro růst buněk je pravděpodobně mřížka o průměru 50 m s drsností podél perimetru 1,9 m, což odpovídá kontaktnímu úhlu s vodou 74,1°.
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Stress resistance of bacterial pure cultures and mixed cultures
Chorvátová, Michaela ; Slaninová, Eva (referee) ; Obruča, Stanislav (advisor)
The purpose of this bachelor thesis was to investigate a stress resistance of bacterial monocultures and defined mixed culture. The theoretical part contains a literary review, which deals with the general stress resistance of bacteria and the dynamics of their growth. Furthermore, polyhydroxyalkanoates are introduced, as well as their involvement into stress response of bacteria. In this review was also elaborated the flow cytometry, significant modern method, which was important part of the experiment. In the experimental part, the resistance to osmotic and temperature stress was studied. For this purpose, monocultures of the PHA accumulating strain Cupriavidus necator H16 and the mutant strain Cupriavidus necator H16/PHB-4 unable to accumulate PHA were used. The defined mixed culture was prepared by cocultivating these two strains. Overall, the accumulation and utilization of PHA, namely poly (3-hydroxybutyrate), increased the resistance of bacteria. The most notable was the increase in the case of osmotic stress, when salt concentrations did not significantly reduce the viability of Cupriavidus necator H16 against a mutant strain which viability decreased with growing intensity of stress. On the other hand, experimental temperatures did not have a significant effect on cell viability. The highest growth of bacteria was recorded, in most cases, at their temperature´s optimum of 30 °C.
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Study of microplastic sorption properties
Hlaváčková, Hana ; Kučerík, Jiří (referee) ; Řezáčová, Veronika (advisor)
There is currently an effort to replace conventional plastics with biodegradable products that will have the ability to replace these substances. One of the possible biodegradable felt, which is currently being studied in detail, is also poly (3-hydroxybutyrate), which is produced by bacteria. This bachelor thesis deals with the sorption of selected substances on poly(3-hydroxybutyrate) microparticles. Substances whose contamination of water sources is a significant problem today have been selected for this work. Specifically, the sorption of the nonsteroidal anti-inflammatory substance ibuprofen, the triazole fungicide tebuconazole and the most common drug caffeine on PHB particles, which fall in the size of the microplastic group, were studied. The method of liquid chromatography with mass detection was used for analyzes.
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Microfibers based on polyhydroxybutyrate for medical applications
Gregušková, Zuzana ; Obruča, Stanislav (referee) ; Přikryl, Radek (advisor)
Diplomová práca je zameraná na mikrovlákna na báze biopolyméru poly(3-hydroxybutyrátu) a ich využitie v medicínskych aplikáciách. Teoretická časť práce sa zaoberá štúdiom procesu tvorby vláken pomocou technológie odstredivého zvlákňovania, jeho kinetikou a faktormi ovplyvňujúcimi vznik a vlastnosti vláken. Teoretická časť sa následne orientuje na krátky prehľad biopolymérov používaných v tejto technológii, charakteristiku materiálu poly(3-hydroxybutyrátu) a taktiež prezentuje návrh potenciálnej cieľovej aplikácie daných mikrovláken. Praktická časť sa koncentruje sa prípravu mikrovláken zo spomínaného poly(3-hydroxybutyrátu). Sledované a optimalizované sú viaceré parametre vedúce k lepšej zvlákniteľnosti materiálu. Praktická časť je rozšírená o modifikáciu polymérneho roztoku prídavkom iných biopolymérov a zmäkčovadiel a prípravu mikrovláken z takto modifikovanej polymérnej zmesi. Pozornosť je venovaná taktiež optimalizácii procesných parametrov. Pripravené mikrovlákna sú následne analyzované a charakterizované viacerými metódami a vzájomne porovnávané s cieľom vyvinúť alternatívu k súčasne používaným substrátom pre rast buniek v 3D.
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Polyhydroxybutyrate modification by grafting of functional groups
Melčová, Veronika ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
Presented bachelor thesis deals with a characterization of the effect of chemical grafting on thermal and mechanical properties of poly(3-hydroxybutyrate). Two grafting methods were chosen, chlorination and fluorination of PHB. The aim of the theoretical part of the work was to create a complete literature review containing basic information about polyhydroxybutyrate and the latest scientific evidence about possibilities of chemical modification of this polymer. The experimental part describes the chemical treatment of the material itself, as well as preparation of samples for testing and performing the selected analysis. Chemically grafted polymers were subjected to thermogravimetric analysis to determine their thermal stability. Thermal behavior of materials was studied by differential scanning calorimetry. Also non-isothermal crystallization of samples was observed in order to evaluate the influence of the grafted halogen atom onto the nucleation activity of the polymer. Selected samples were also subjected to dynamic mechanical analysis and tensile test.
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Biocomposite material for 3D print in the field of regenerative medicine
Chaloupková, Kateřina ; Obruča, Stanislav (referee) ; Přikryl, Radek (advisor)
The presented thesis deals with preparation of material for use in regenerative medicine based on poly(3-hydroxybutyrate) and its characterization. In addition to poly (3-hydroxybutyrate), there were used other materials lactic acid (PLA), tricalcium phosphate (TCP) and two types of plasticizers Citroflex®B-6 (CB6) and Syncroflex3114 (S3114). These materials were selected based on their biocompatibility and, in the case of TCP, also bioactivity. TCP allows new bone to grow on the surface of the scaffold. PLA was used to improve the mechanical properties of the material. Both plasticizers have been used to improve the processability of the material. Theoretical part of this work contains a literature review describing basic information about used materials. Aim of the experimental part is to prepare the material, characterization of properties and determination of printability on a 3D printer. The material is examined for thermal properties by thermogravimetric analysis and differential scanning calorimetry. This work also deals with the matter of 3D printing, especially FDM technology. It has been found that materials containing the syncroflex plasticizer are better processed and therefore printed on a 3D printer. The printability tests performed are temperature towers and filling studies. Printed samples were subjected to mechanical tests of tensile and bending tests. Experiments of cytotoxicity and biocompatibility of the material were also performed. Within the work, TCP particles were characterized using a particle size analyzer. The average TCP particle size is 10,76 µm. Using SEM-EDX, the distribution of TCP in sample filaments was subsequently observed, where it was found that by mixing TCP particles with the remaining components of materials, TCP particles agglomerate into formations up to 20 µm in size. Roughness of materials was determined by confocal microscopy. Cytotoxicity was also tested in the extracts of samples on mouse fibroblasts. Cytotoxicity was determined by metabolic activity assay and light microscopy. The metabolic activity test proved the biocompatibility of the observed materials; therefore, it was possible to perform cell proliferation and biocompatibility tests directly on the samples. Assays were performed using human mesenchymal stem cells. DNA quantification was used to determine cell proliferation. Shape of cells was subsequently observed by confocal microscopy. Tests confirmed growth of cells and their appropriate shape. Stem cell differentiation into bone was performed by measuring alkaline phosphatase activity.
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