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Preparation and characterization of magnetic nanoparticles modified by surfactants
Solnička, Ondřej ; Másilko, Jiří (referee) ; Enev, Vojtěch (advisor)
Theme of this bachelors thesis was preparation and characterization of iron(II, III) oxide nanoparticles. Those nanoparticles were modified by surfactants. The surfactants which were used for modifiation were CTAB, TTAB and Septonex. Prepared and modified nanoparticles were taken for characterization by using methods of elemental analysis, thermogravimetry, dynamic light scattering and transmission electron microscopy (TEM). Results from each measurement shows that nanoparticles modified by CTAB had on average 85.9 nm in diameter, TTAB size was on average 108.3 nm and the last nanoparticles with Septonex had 246.6 nm in diameter on average. Prepared modified nanoparticles except the Septonex ones were stable enough to not aggregate. Septonex modified nanoparticles had greater tendenty to aggregate.
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Physicochemical characterization of soil humic substances isolated from Fluvisol
Šátková, Eliška ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis is focused on the physicochemical characterization of humic substances that are isolated from fluvisol. Humic substances were isolated by a standard procedure according to the International Humic Substances Society (IHSS). Extracted humic substances were further characterized by thermal and spectrometric methods, which include elemental (EA) and thermogravimetric analysis (TGA), UV/Vis, and FTIR spectrometry. Potentiometric titration was an important contribution to characterization. Based on the obtained data obtained from the EA and TGA, the content of biogenic elements and the thermal stability of HL were determined. Absorption coefficients were calculated from the measured UV/Vis spectra to determine the aromaticity and average molecular weight of HL. The HL functional groups were determined by FTIR spectra, and the acidity was determined by potentiometric titrations. The obtained results very well characterized the individual humic substances isolated from fluvisol.
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Use of thin layer chromatography for fractionation of humic substances isolated from oxyhumolite
Hegrová, Nela ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The main goal of this thesis was to optimize the fractionation of humic substances (HS) using the method of Thin-layer chromatography, so that it can be used for physico-chemical characterization of the obtained individual organic fractions. Due to the high content of HS in the natural oxyhumolite matrix this oxidized brown coal was selected as a source of these biocolloid compounds which were isolated according to the international IHSS procedure. The sample of native oxyhumolite and oxyhumolite after extraction was characterized by thermal techniques such as thermogravimetric (TGA) and elemental analysis (EA). The above-mentioned oxyhumolite samples were further analyzed by Fourier transform infrared spectroscopy, mainly for deeper understanding of their structure in terms of an organic matrix containing HS. Characterization of isolated HSs was performed by the following thermochemical and spectrometric techniques, elemental analysis, thermogravimetry, ultraviolet and visible electromagnetic absorption (UV/Vis) molecular spectroscopy, Fourier transform infrared spectroscopy and steady-state fluorescence spectroscopy. Molecular absorption spectroscopy (UV/Vis) and steady-state fluorescence spectroscopy were used for physicochemical characterization of individual organic fractions.
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Soil gel as a suitable matrix for the study of humic substances in the soil ecosystem
Černý, Pavol ; Pekař, Miloslav (referee) ; Enev, Vojtěch (advisor)
This master's thesis deals with a complex issue of soil gels. The main goal of this work is to optimize the process of isolation of soil gels out of the soil matrix. Isolation is carried out using only water and therefore represents a promising method for study of humic substances (HS) in natural form. Modal brown earth from the area of Veverské Kninice was used as a soil matrix for isolation. The isolated soil gel was phisicochemically characterized by thermal and spectroscopic methods. By using EA and TGA, the content of biogenic elements in the organic component of soil gel and the content of the inorganic component was determined. The inorganic component represents a majority share in structure of soil gel with values up to 90 % w/w. Mineralogical composition of the inorganic component was described using XRD, with quartz being the most represented. Chosen macro and microelements were determined by ICPOES and the results show a noticeable increase in the content of some elements, that form complexes with HS. Organic component was studied using spectroscopic methods FTIR and XPS, which clearly showed that the primary components of the organic matrix are HSs. For this reason, absorption coefficients EET/EBZ, E2/E3 a E2/E4 were determined using UV/Vis spectrometry. Morphology of isolated soil gels was studied by using SEM and the photographs show mineral particles covered with clusters of humic matrix.
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Program-controlled freeze drying for the preparation of the delivery system of native hyaluronan and hydrophobic molecules
Waczulíková, Kristína ; Sedláček, Petr (referee) ; Enev, Vojtěch (advisor)
The amphiphilic nature of the hyaluronan biopolymer facilitates interactions between its hydrophobic portions of the chain and the hydrophobic ligands, making it one of the promising compounds that can be used as a suitable carrier for drug delivery. Therefore, the aim of this diploma work was by means of a program-controlled freeze-drying to prepare a system based on native hyaluronan, which would be capable of transporting hydrophobic drugs. Perylene, pyrene, prodan and 1,6-diphenyl-1,3,5-hexatriene fluorescence probes were used as model compounds to simulate hydrophobic drug-hyaluronan interactions. Freeze-drying efficiency was studied using infrared spectrometry and scanning electron microscopy. ATR-FTIR spectrometry confirmed for all probes but pyrene the hydrophobic interactions between the hyaluronan and probe molecules based on the presence of the C=C bond valence vibration absorption band in the aromatic probe rings. From the IR spectra, it was not possible to confirm with certainty the presence of residual tert-butyl alcohol in the samples. SEM photographs revealed that increasing the pressure during drying process had a positive effect on the quality of the lyophilized sample in the second series of samples. Interactions of individual fluorescent probes with hyaluronan were studied using steady-state and time-resolved fluorescence spectrometry. Positive results have been obtained, indicating the presence of fluorescent probes interacting with the hydrophobic regions of the hyaluronan chains. The results of this work can contribute to the development of carrier systems in the field of targeted drug distribution.
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Interaction of Ibuprofen with Different Soil Types
Krajňáková, Soňa ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
Táto práca sa zameriava problematiku interakcie ibuprofénu s pôdnym systémom. Popísané sú jeho základné vlastnosti, správanie a faktory ovplyvňujúce toto správanie. Vo všeobecnosti najvplyvnejšími faktormi je prítomnosť pôdnej organickej hmoty v pôde a pH. Ibuprofén patrí do skupiny nesteroidných protizápalových liečiv. Patrí medzi ľahko dostupné a vysoko konzumované liečivá. Toto prispieva k jeho narastajúcemu transportu a kontaminácii životného prostredia. Jeho prítomnosť v životnom prostredí môže pôsobiť negatívne na živé organizmy. V experimentálnej časti bol preskúmaný vplyv pôdnej organickej hmoty a pH na sorpciu a desorpciu ibuprofénu. Použité boli tri pôdy získané z odlišných regiónov Českej republiky. V rámci procesu sorpcie a desorpcie boli použité koncentrácie v rozmedzí 1 až 10 mg/l. Vplyv pH na sorpciu a desorpciu bol preskúmaný použitím koncentrácie ibuprofénu 10 mg/l a Britton-Robinsonovho pufru s pH 3, 7 a 10. Detekcia ibuprofénu v jednotlivých vzorkách bola uskutočnená pomocou UV-VIS spektrometrie a kvapalinovej chromatografie s hmotnostne spektrometrickou detekciou.
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Study of decomposition of organic matter in soil using the method of "tea bags"
Lišková, Kateřina ; Sedláček, Petr (referee) ; Enev, Vojtěch (advisor)
The main aim of this master thesis was to introduce an optimal method which could be used for study of a decompostion of an organic matter in a soil. For this purpose was chosen based on a literaly review so-called tea bag method. With regard to the completeness of the work, a physico-chemical characterization of the soil environment and HS isolated from it was also performed. The degraded organic material was then further characterized using thermogravimetric analysis, elemental analysis, FT-IR spectroscopy, and the total content of water-extractable polyphenolic substances in the samples was also determined.
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Development and optimization of ointment preparation for burn healing
Müllerová, Kristýna ; Sedláček, Petr (referee) ; Enev, Vojtěch (advisor)
This bachelor's thesis aims to prepare ointments based on an ointment base with the addition of a bioactive component of chlorophyll according to a recipe from an unknow doctor. The basic characteristic of emulsions was performer in the theoretical part, their instability and possible methods of stabilization were described. Furthermore, the reader is acquainted with the bioactive substance of chlorophyll, selected ointments for the healing of burns and wounds and finally with the use in medicine. In the Experimental part, the preparation of emulsion bases of ointment was described. Based on a performed analysis of stability using analytical centrifuge, two ointments bases were selected, to which other components were added – chlorophyll, beeswax, and chamomile extract. The stability of completely prepared ointments was studied at 25 °C and 37 °C, this analysis was performed even after a longer time interval. Using ATR-FTIR spectrometry the present functional groups were identified at prepared ointments, individual components of the ointments base and chlorophyll. Based on the stability measurement of the prepared ointments and rheological measurements (oscillation and rotational measurements), it was evaluated that the best properties were shown by the prepared ointment with an ointment base consisting of 30 wt. % white vaseline and 70 wt. % synderman.
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Study of bulk and hydration water in hydrogel systems suitable for medical applications
Řihák, Marek ; Sovová, Šárka (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis focuses on a preparation of hydrogel systems based on hyaluronan and Septonex and on a design and optimalization of quantitative analysis of hyaluronan and Septonex in a supernatant after gelation. This work compares hydrogels formed from hyaluronan of two different molecular weights. The calibration curves of hyaluronan and Septonex were used to evaluate the experimental data. The thermogravimetric analysis and Fourier-transform infrared spectroscopy were used for the characterization of properties of the samples. The utilisation of the mentioned techniques to study molecular water subpopulations was discussed according to the obtained results.
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Study and characterization of organic substances in a biochar sample
Vojáčková, Beáta ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis characterizes biochar from a physico-chemical point of view. The theoretical part deals with biochar as a soil conditioner, its properties, use, production, and last but not least, effect of its sorroundings. For better characterization of organic and inorganic matter a phosphate buffer was used. This buffer ensures their specific extraction due to a neutral pH. The second path is to use rainwater, which simulates the condition of the soil environment. In the experimental part are discussed both; purified buffer-extracted samples and rainwater samples, which were studied by thermogravimetric analysis (TGA), elemental analysis (EA) and by infrared spectroscopy with Fouier transform (FTIR-ATR). Conductivity and pH were also measured. Moisture and ash content, which represent the inorganic non-combustible fraction, were determined using thermogravimetry. The extraction yields were converted to ashless wt. % based on these values. Results of EA provided us with information on the content of biogenic elements and basic physico-chemical characteristics of biochar. In contrast, the FTIR method defined the presence of individual functional groups and specific constitutive units, which are present in the extracts. This information allows us to better understand the environmental impact of biochar on the soil ecosystem.
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