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Determination of content of selected nonsteroidal antiphlogistic – Ibuprofen in drugs using UV/Vis and FTIR spectrometry
Lindovský, Jiří ; Sovová, Šárka (referee) ; Enev, Vojtěch (advisor)
The main aim of bachelor thesis was to validate the content of the nonsteroidal antiphlodstic in drugs using spectrometric methods and subsequent comparison of results. Specifically, the thesis is focused on Ibuprofen, which is used mainly as analgesic and antipyretic. This substance was chosen for its significant ability of absorbing electromagnetic radiation in ultraviolet and infrared regions of spectra. For this purpose, various generics were selected and analyzed by molecular absorption spectrometry (UV/Vis) and infrared spectrometry with Fourier transform (FTIR). Very important factor influencing chemometric properties of the obtained results was optimalization of the spectrometric methods. After designing the working procedure, sample solutions were prepared from Ibuprofen-containing dosage forms using suitable solvent and these samples were analyzed spectrometrically. The content of Ibuprofen in individual samples was calculated from the measured UV/Vis and FTIR spectra using method of standard addition. The results show that infrared spectrometry seems to be more suitable method for determining the Ibuprofen content. Nevertheless, it should be noted that the choice of a suitable extractant is very important step in the determination. The information obtained from this bachlor’s thesis could be used in future routine inspections and monitoring of drugs.
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Study of biological activity of superabsorption polymers
Männlová, Adriana ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
This thesis is focused on the study of the biological activity of superabsorbent polymers for environmental and agricultural applications. Generally these hydrogels perform many functions in the soil, which is increasingly stressed by treatment with synthetic fertilizers and thus loses their natural properties, such as the uptake of moisture. Addressing these issues is now in superabsorbent polymers that can absorb and also retain a lot of water around the root system as long as possible. They can perform the function of carriers gradual release fertilizer. Based on the literature review was designed and conducted the study of biological activity in the soil model on corn sown. SAPs were prepared in the framework of contract research Faculty of Chemistry of the Technical University in Brno with the company Amagro Ltd. The content of the experiment, the superabsorbent polymer, observing effects on the growth of dent corn. He was also studied root system for absorption of nutrients. Further changes were observed rheological properties of prepared superabsorbent polymer, superabsorbent polymers since they provide a source of nutrients and help to retain moisture in the soil, it is necessary to know their viskoelstick properties even at temperatures below freezing. This work is based primarily on the use of great motivation superabsorbent polymers in agriculture and also in environmental protection.
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Stability of natural oils used in cosmetics and pharmaceuticals
Milerová, Helena ; Enev, Vojtěch (referee) ; Hurčíková, Andrea (advisor)
The bachelor's thesis deals with the issue of stability of selected plant oils used in the cosmetic industry. Six oils were subjected to analysis using differential scanning calorimetry (DSC), which determined the oxidation onset temperatures for all samples. The aim of the thesis is to evaluate the use of the DSC method for obtaining data on the thermo-oxidative stability of plant oils. For comparison, the samples were also measured using the Rancimat method, a commercially established procedure in which the samples were exposed to elevated temperature using air flow. The results yielded induction periods, which indicate the time until the sample starts to oxidize. After measuring the samples using both methods, the oils were ranked according to their oxidative stability from the most stable to the least stable. The resulting sequences from both methods were nearly identical. DSC has proven to be a suitable method for measuring the thermo-oxidative stability of plant oils.
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Effect of freeze-drying conditions on the hydrophobic interaction between native hyaluronan and fluorescent probe
Říha, Karel ; Venerová, Tereza (referee) ; Enev, Vojtěch (advisor)
The biopolymer native hyaluronan possesses the amphiphilic character of its molecule. Which means that it contains both a hydrophilic and a hydrophobic part. This character of the molecule favors interactions between hydrophobic ligands and hydrophobic parts of the chain, making hyaluronan one of the compounds potentially suitable as drug carrier systems. The aim of this bachelor thesis was to prepare a carrier system based on hyaluronan and model hydrophobic compounds (fluorescent probes). The fluorescent probe we used was pyrene. Furthermore, the work was focused on the study of lyophilization conditions, which would lead to the actual influence of hydrophobic interactions between the substances we used. The main techniques that served us to verify the effectiveness of lyophilization (in the sense of supporting the creation of a hydrophobic effect between individual hyaluronan chains) were: thermogravimetric analysis, fluorescence spectrometry, and last but not least, infrared spectroscopy with Fourier transformation.
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Program-controlled freeze drying for the preparation of the drug-delivery system based on polysaccharide and hydrophobic molecules
Dufková, Michaela ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
The lyophilization process favors the hydrophobic effect between the individual dextran chains. This hydrophobic effect allows hydrophobic drugs to settle and remain within the biopolymer. Due to hydrophobic effect, dextran can serve as a carrier for the distribution of hydrophobic drugs. The goal of this thesis was to prepare a carrier system based on native dextran using program-controlled freeze-drying. Hydrophobic drugs were modeled using the fluorescent probes pyrene and prodane. The effectiveness of promoting the hydrophobic effect was studied using infrared spectrometry, fluorescence spectrometry and scanning electron microscopy. Using ATR-FTIR spectrometry, a shift of the absorption band of thevalence vibration of the C–O bond in OH groups in alcohol was observed. Using fluorescence spectrometry, the emission polarity index was calculated for pyrene from the 1st and 3rd maximum fluorescence intensity, and for prodan, a shift of the maximum fluorescence intensity to lower wavelengths was observed. SEM images showed that during the lyophilization process, the dextran structure formed a dense network of fibers, indicating the presence of many sites with a higher content of hydrophobic domains. Positive results were obtained with these methods, which proved the positive effect of lyophilization on the formation of a hydrophobic effect between individual polysaccharide chains. The results may contribute to the development of carrier systems for hydrophobic drugs.
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Physicochemical characterization of soil humic substances isolated from modal brown soil
Churina, Iuliia ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis deals with the physicochemical characterization of soil humic substances isolated from brown earth modal based on the international IHSS procedure. Humic substances are organic compounds occurring in soil and have a significant influence on soil processes and properties. The aim of this work is to obtain detailed information on the physical and chemical properties of humic substances such as mean molecular weight (Mr), spectral characteristics, elemental composition and thermal stability. Soil humic substances samples were characterized by thermal techniques such as thermogravimetric (TGA) and elemental analysis (EA). Different instrumental methods such as UV/Vis spectrometry, infrared spectrometry and fluorescence spectrometry were used to analyze the samples. The results of this work can contribute to a better understanding of soil processes and properties, which can lead to improved agricultural production and environmental protection.
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Enzymatic Degradation of Biochar
Zmijová, Marie ; Enev, Vojtěch (referee) ; Kalina, Michal (advisor)
Human prosperity is inextricably linked to healthy soil. It turns out that the application of biochar improves soil properties and, as a result, also the growth and yield of plants. The presence and activity of soil biota contributes to soil quality, but it also excretes compounds that can degrade biochar. Experiments simulating the action of enzymes and root exudates were carried out in order to find out whether there are physico-chemical changes in biochar. Three biochars, which were chosen for this purpose were degraded using an H2O2 solution, simulating enzymatic action. Samples were subsequently analyzed using TGA, FTIR, SEM and contact angle measurement. It was found that the amount and type of degraded biochar matter depends on the parameters of its production. The amount of functional groups containing oxygen on the surface of biochar rises due to enzymatic oxidation and the surface’s hydrophobicity decreases as a result. An extraction test using citric acid, a root exudate representative, showed that the sample had been washed more effectively, leading to a higher proportion of organic matter in the biochars. In the obtained leachates, the amount of elements released from the biochar was monitored using ICP-OES. The initial washing led to the release of the largest amount of micro and macro elements, which caused a decrease in the pH value of the solution and an increase in conductivity. The pH value of the solution had a major influence on the amount of released multivalent elements (Ca, Mg). The combination of these changes that may occur in the soil system probably does not change the desired effect of biochar and its use may be beneficial in the long term.
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Program-controlled freeze drying for the preparation of the delivery system based on hyaluronan and real drugs
Řihák, Marek ; Sedláček, Petr (referee) ; Enev, Vojtěch (advisor)
The aim of this thesis was to prepare native hyaluronan-based carrier systems using the lyophilisation as a suitable method to ensure an interaction between certain drugs and the polymeric structure which would lead to an increased solubility of hydrophobic drugs. For the preparation of such a system the tert-butyl alcohol was used as a co-solvent with the ability to support hydrophobic effect between the drug and a hydrophobic domain of hyaluronan. Since all polar domains of hyaluronan are located in the equatorial position, the axial position is occupied by hydrogens and therefore the molecule gains the amphiphilic character. Previous studies have confirmed that freeze-drying is a useful method for a carrier system preparation. However, this study focuses on the preparation of such systems with samples of real drugs, which were previously replaced by fluorescence sondes. Since all drug samples have good fluorescence characteristics, the fluorescence spectroscopy was used as the main method to determine the success of the preparation. Other methods included a thermogravimetric analysis and the infrared spectroscopy with Fourier transformation. All the mentioned methods have confirmed that lyophilisation is a useful method for the preparation of the carrier systems with real drugs. Great results have been achieved in the terms of the solubility of freeze-dried systems. In the last step, the co-solvent residues were determined by head-space solid phase microextraction. This method also provided some valuable information and confirmed that tert-butyl alcohol could be found in the lyophilised systems only on very low levels.
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The long-term stability and properties of a skin cream with addition of liposomes
Müllerová, Kristýna ; Pekař, Miloslav (referee) ; Enev, Vojtěch (advisor)
The aim of the thesis was to design a formulation and subsequently prepare a native skin cream and skin creams enriched with liposomal particles with encapsulated vitamin E. After preparation of the skin creams, their stability and rheological properties were studied at given time intervals during storage for 12 weeks. The stability of the prepared samples was determined using a LUMiSizer analytical centrifuge with STEP-Technology. Among the rheological properties, changes in the rate of structure recovery of the formulations were monitored, as well as changes in zero and infinite viscosity, which can be presented as changes in viscosity during product storage and changes in viscosity during application and spreading on the skin. All stability and rheological tests were performed for a temperature of 25 °C, which also corresponded to the storage temperature, and for a temperature of 37 °C, which approximately corresponds to the human body temperature. According to the results, the sample without the addition of liposomes showed the highest stability and the skin cream with the addition of 10 wt.% liposomes at 1 week of age showed the best spreadability. Next, the characterization of liposomal particles was performed. Finally, a sensory analysis was performed where the evaluators compared the fresh native skin cream, the native skin cream at 12 weeks of age, the fresh skin cream with the highest liposome content and the skin cream with the highest liposomal particle content at 12 weeks of age.
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Polarity-based sequential extraction method for the study of organic matter isolated from biochar
Vojáčková, Beáta ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
This master’s thesis completely charakterizes the organic matter of biochar from a physicochemical point of view. The theoretical part is focused mainly on the use of biochar in technology industry, substance content, extraction and instrumental techniques used for its study. A Soxhlet apparatus and the method of sequential fractionation by a series of six organic solvents, which were ranked based on their increasing polarity, were used to extract the matter. The experimental part discusses the analysis of the obtained samples using thermal methods such as thermogravimetric (TGA) and elemental analysis (EA). In our case optical methods were used also; spectrometry with Fourier transform (FTIR-ATR), ultraviolet-visible (UV-VIS) and fluorescence spectrometry. Thanks to the scanning electron microscopy (SEM) were obtained images of the biochar surface. Continuous characterization including the results of the biogenic element content, individual functional groups and the values of established indices, allowed us to define the organic parts of biochar and contributed to the implementation of better methodology regarding the investigated issue.
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