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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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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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Influence of metal ions on microorganization of humic substances
Odehnalová, Nikola ; Krouská, Jitka (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focused on the study of influence of metal ions on microorganization of humic substances. This issue was studied on a sample od fulvic acid. Solution of cocentration 1 g/l was prepared from this sample. This solution was ten titrate with solutions of copper, calcium and magnesium ions. For this purpose, methods of dinamic and electrophoretic light scattering were used. The results obtained by these methods show that the solution of fulvic acid is the most made by associated molecules of fulvic acid. The size of molecules became larger and larger during titrations. Copper was sorpted the most.
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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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Interaction of negatively charged vesicular systems based on ionic amphiphilic pairs with polycations
Fardová, Lucie ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This work is focused on the preparation of negatively charged vesicular systems from amphiphilic pairs deprived of counterions and their interaction with the polycation. First, vesicular systems were prepared from the surfactants sodium dodecyl sulfate and cetyltrimethylammonium bromide. The addition of cholesterol and phosphatidic acid stabilized and at the same time gained a negative charge. Subsequently, there was an interaction with the polycation diethylaminoethyl-dextran hydrochloride. The systems were investigated by the measuring of particle size, zeta potential, generalized polarization and anisotropy. The measurement of generalized polarization was enabled with the laurdan probe and measurement of anisotropy was performed with the introduction of the 1,6-diphenyl-1,3,5-hexatriene probe. The results indicate the successful preparation of stable, negatively charged systems that interacted with positive diethylaminoethyl-dextran hydrochloride, which affected the behavior of the outer membrane but not the inner. The systems were still stable.
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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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Microcalorimetric and Light Scattering Methods in the Study of Interactions in Biopolymer - Surfactant System
Šojdrová, Kamila ; Mravec, Filip (referee) ; Krouská, Jitka (advisor)
Biopolymer surfactant systems have been studied by using different physico chemical methods. As the biopolymer, it was chosen high (1400–1600 kDa), medium (250–450 kDa) and low (8–15 kDa) molecular weight sodium hyaluronate. Two cationic surfactants – cetyltrimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex) were selected to provide polyelectrolyte complexes with oppositely charged hyaluronan. The critical aggregation concentration of the surfactant in the system was monitored by dynamic light scattering (Zetasizer Nano ZS). SEC-MALS method was used for the description of the conformation of sodium hyaluronate of different molecular weights and polyelectrolytes complexes hyaluronan surfactant after reaching the aggregation point. Isothermal titration calorimetry (ITC) was used to determine the critical aggregation concentration of the surfactant by monitoring the thermal changes accompanying the aggregation of the system. It was found out that the increasing molecular weight of hyaluronan in these systems decreases the critical aggregation concentrations and conversely.
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Preparation and Characterization of Iron Complexes with Amino Acids
Bednárová, Paula ; Hurčíková, Andrea (referee) ; Kalina, Michal (advisor)
This bachelor thesis focuses on the preparation and characterization of iron complexes with amino acids. The work in the theoretical part is focused on specification of iron as an essential element in living organisms, on his abilities to build complexes and on its wide range of biological attributes of these complexes, which can be natural or leading to various disorders of their metabolism. The studied literature is oriented on preparation of Fe(III) complexes with amino acids. In the experimental part of work we deal with titrational setting of zeta potential and critical aggregation concentration which were set only for amino acids L-lysine and an Aspartic acid. We also deal with coagulation reactions that had low yield in most of the selected amino acids except cystein, which doubled its amount after the modification of the conditions. We have stated that the resulting yield depends mainly on the type of used amino acid as well as on the used solvent and its amount used in synthesis.
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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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Influence of dispersion parameters on formation of vesicular systems
Vajcíková, Katarína ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
The work describes a method for the preparation of catanionic vesicular systems using the method of ultrasonic dispersion in order to find the most suitable parameters for the preparation of a system with long–term physical stability. The parameters compared were the amplitude of the ultrasonic wave, the energy used for dispersion, and the volume of deionized water used to prepare a system consisting of the negatively charged surfactant sodium dodecyl sulfate and the positively charged surfactant hexadecyltrimethylammonium bromide. To increase stability and provide a positive charge, the surfactant dimethyldioctadecylammonium chloride was used and cholesterol was also added to increase stability. The individual systems were compared over time because of their size, zeta potential and turbidity of the solution. Particle size and polydispersity coefficient were measurement by the dynamic light scattering method. The zeta potential was determined by electrophoretic light scattering, and the turbidity was monitored by UV-VIS spectrophotometry based on the measurement of turbidity. The results present the most suitable parameters of ultrasonic dispersion using Bandelin SONOPULS UW 3200. The use of these parameters shows the emergence of systems with long–term physical stability, which means that they can be used for other applications.
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