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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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Light Scattering Techniques in the Study on Formation of Polyelectrolyte Complexes in the System Biopolymer-Surfactant
Valečková, Vendula ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This master thesis is dealing with the use of light scattering techniques in the study on formation of polyelectrolyte complexes in the system biopolymer-surfactant. Sodium hyaluronate was chosen as biopolymer and cetyltrimethylammonium bromide and karbethopendecinium bromide were selected as surfactants. The first precipitation experiments were performed to determine the optimal concentration range of surfactants for subsequent titration measurements performed on Zetasizer Nano ZS and for SEC-MALS analysis. The key parameters obtained from these measurements were the values of critical aggregation concentrations in hyaluronate-surfactant systems. It was found out that the increasing molecular weight of hyaluronan in these systems is causing reduction of obtained values of critical aggregation concentrations. Changes of Z-average particle size, zeta potential, polydispersity index, conformation plot, radius of gyration and molecular weight in the hyaluronan-surfactant system were monitored during experiments.
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Effects of hyaluronan on properties of Opthalmo-Septonex eye drops
Chromá, Kateřina ; Němcová, Andrea (referee) ; Pekař, Miloslav (advisor)
Modification of eye drops using hyaluronan to increase retention time on the eye surface. Using modification of Mahrous method have been determined concentration of Septonex in water. Than using gradual addition of hyaluronan into Opthalmo-Septonex eye drops was investigated appropriate concentration for membrane dialysis. With membrane dialysis was observed interaction hyaluronan-septonex. Than was determined size and charge of particles.
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Characterization of polyelectrolyte complexes using structural and thermal analysis
Řiháčková, Barbora ; Smilek, Jiří (referee) ; Krouská, Jitka (advisor)
This master thesis deals with study of chitosan-lignohumate, chitosan-polystyrenesulfonate, chitosan-alginate and chitosan-carrageenan polyelectrolyte complexes. The work was motivated by research of finding suitable alternative substance for lignohumate. The molecular weights of substances were characterized using SEC-MALLS. A degree and a character of the interactions between polyelectrolyte were studied by isothermal titration calorimetry and dynamic light scattering method. The calorimetric experiments proved that decreasing concentration of samples causes decreasing of heat flow. The best calorimetric measurements were provided by adding chitosan into polymer solution. The interactions between chitosan and polyanions and influence of mixing order were proved also by measuring intensity of zeta potential, Z-average of particle size and turbidity. New chitosan-based materials have a big potential in agriculture and medicine.
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Study of hyaluronan-albumin systems using light scattering methods and calorimetry
Sereda, Alena ; Hermannová, Martina (referee) ; Chytil, Martin (advisor)
This thesis, which is a continuation of the previous Bachelor thesis, is dedicated to the study of polyelectrolyte complexes between hyaluronan (HA) and bovine serum albumin (BSA). Interactions between HA and BSA and a formation of complexes were studied by SEC-MALLS method, where a molar mass, a root mean square (rms) radius, a hydronamic radius and an intrinsic viscosity of particles of the system were defined. Furthermore the interactions were studied by calorimetric measurement ITC, where thermodynamic character of complex formation was determined. Additionally, dynamic and electrophoretic light scattering methods (DLS and ELS) were applied, where hydrodynamic radius and a value of the zeta potential were defined. Also the effect of higher temperature on the character and complex formation was examined by SEC-MALLS and ITC measurements. The interactions were confirmed at any of the used media, but with different efficiency. It was also proved that complexes become smaller in their radii and viscosity with growing BSA concentration. Furthermore it was proved, that the high ionic strength hinders surface charges of HA and BSA molecules and minimizes their mutual interactions. At the higher ionic strength the radii of the complexes, their intrinsic viscosity and zeta potential are increased. The higher temperature has only minimal effect on the formation of the complexes.
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Possibilities of using recycled glass for the preparation of blended cements
Dobrovolný, Petr ; Všianský,, Dalibor (referee) ; Dvořák, Karel (advisor)
This work focuses on the possibility of using recycled glass in the manufacture of blended portland cements. It examines the possibilities to improve pozzolanic properties of recycled glass with new milling processes, the formation of agglomerates material during the course of grinding and their subsequent effect on the hydration process of binders. It is also the optimization of the grinding process with respect to the wear of grinding bodies, grinding energy consumption and maximize the performance of the mill.
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Preparation of high sulphate binders and study of their properties
Dolák, Dušan ; Štenko,, Miroslav (referee) ; Dvořák, Karel (advisor)
Thesis is indirectly connected to many years of research in field of sulphate binders. Work is focused on modifying of properties of alfa and beta gypsum, mainly on reduction of water ratio. We monitored effect of addition of chloride salts, carbonates and sulphates on zeta potential and its measurement. Part of thesis is also focused on laboratory production of beta plaster from secondary materials and optimization of grinding process to achieve required criteria.
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Study of influence of quantum dots to biological systmes and their components
Koudelková, Zuzana ; Zítka, Ondřej (referee) ; Provazník, Ivo (advisor)
The aim of this thesis is to summarize the available evidence about quantum dots and their effects on living systems. The text describes methods for the preparation of quantum dots with respect to their characteristics (size, fluorescence wavelength) and methods of quantum dots bio-functionalization of biomolecules. In living organisms is a large number of proteins, because these are considered as one of the main components of the interaction of organisms. Therefore, the work also provides basic information about proteins. Finally, there are described various methods by which the quantum dots may be characterized mainly by differential pulse voltammetry measurement zeta potential and fluorescence measurement. The main objective of this work is to propose models of different environments in which will be degradation of quantum dots with regard to the evaluation of acquired kinetic parameters for predicting the stability of individual quantum dots.
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SEC-MALLS study on hyaluronan-albumin interactions
Sereda, Alena ; Kalina, Michal (referee) ; Chytil, Martin (advisor)
This work is focused on interactions of hyaluronan (HA) and bovine serum albumin (BSA). These interactions were studied by SEC-MALLS method, where molar mass, root mean square (rms) radii, hydronamic radius and intrinsic viscosity of particles of the system were defined. Additionally, interactions were examined by measurement of DLS and zeta potential, where hydrodynamic radius and a value of the zeta potential were defined. The interactions were confirmed at any of the used media, but with different efficiency. Furthermore it was found out, that the high ionic strength minimizes the range of the interactions, magnifies the radii of the complexes, their intrinsic viscosity and zeta potential. It was proved that complexes become smaller in their radii and viscosity with growing BSA concentraton.
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The Study of Biopolymers Stability Using Light Scattering Techniques
Kratochvíl, Zdeněk ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
The stability of chosen biopolymers (or simple carbohydrates and amino acids) was in-vestigated using light scattering methods. Samples were prepared by dissolving the sub-stance in deionised water or in diluted acetic acid. Firstly, the effect of increasing concen-tration on zeta potential was observed and the optimal concentration for the next measure-ments was determined. Afterwards, the stability and the molecular weight of used sub-stances were studied during long-time storage in different time intervals. It was found out that chitosan, CMC, hyaluronate and sodium alginate were subjected to degradation whereas increase of the molecular weight and the zeta potential was observed in case of BSA. In the end, the samples were exposed to several different external effects, namely the influence of different temperatures, UV radiation and increasing ionic strength. The results showed that rather higher temperature has a significant impact on biopolymers stability. However, used biopolymers were hardly affected by UV radiation except BSA whose molecular weight increased considerably. Decrease of the zeta potential absolute values and the molecular size usually occurred with increasing ionic strength. The change of molecular weight was not detected.
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