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Hyaluronan micro- and nanoparticles
Mourycová, Jana ; Marián, Lehocký (referee) ; Pekař, Miloslav (advisor)
The aim of this thesis was to prepare hyaluronic acid micro- and nanoparticles based on electrostatic interactions with oppositely charged molecules. Following parameters were monitored: correlation function behavior, the particle size and zeta potential value. At the beginning, it was necessary to study the behavior of hyaluronan in solution by dynamic light scattering measurement. Micro- and nanoparticles were prepared by mixing different volume ratios of negatively charged hyaluronan and positively charged polyarginine or cetyltrimethylammonium bromide. Micro- and nanoparticles were prepared in aqueous solution as well as in 0,15 M sodium chloride solution (physiological solution). In the case of the hyaluronan solution a polydisperse character of hyaluronan was detected. It was found that the dissolution of hyaluronan in the physiological solution gives us the smaller particle size in opposite to particle size obtained from the same concentrations of hyaluronan dissolved in water. Furthermore, it was found that systems composed of hyaluronan and polyarginine create particle size of about 100 nm. Whereas systems consisting of cetyltrimethylaminoum bromide and hyaluronan form larger particles, in units of hundreds of nanometers, the particle size in physiological solution were smaller than the same systems dissolved in aqueous solution.
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Hydrogels with incorporated vesicular systems
Kalendová, Lucie ; Pekař, Miloslav (referee) ; Venerová, Tereza (advisor)
This bachelor thesis deals with the incorporation of vesicular systems into polysaccharide – based hydrogels. The chosen vesicular systems were Ion Pair Amphiphile vesicles (IPA), which consist of cetrimethylammonium bromide, sodium dodecyl sulfate, dioctadecyldimethylammonium chloride and cholesterol. The work is divided into two parts. In the first part, interactions between IPA vesicles and sodium hyaluronan and interactions between IPA vesicles and sodium polystyrene sulfonate were studied. Even though interactions occured, it was not possible to prepare a hydrogel based on these interactions. The second part of this work deals with incorporation of IPA vesicles into an agarose – based gel when heated. Particles of two different concentrations (1 mmol·l1 and 2 mmol·l1) were used. The effect of the IPA particles on the properties of the gel was observed with rheological measurements. The results showed that the gel with incorporated particles has a longer linear viscoelastic region and that there were no interactions between the IPA particles and the gel. The particles only fill the gaps of the gel network. Different behaviour within the gels with different concentrations of IPA vesicles was not observed.
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Microrheology modeling with COMSOL Multiphysics package
Koláček, Jakub ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis focuses on modeling Brownian motion using the COMSOL Multiphysics package and its Particle Tracing module. The aim of the work is to design and create elementary models that will be able to suitably simulate the movement of microparticles in viscous and viscoelastic environments, which can later be used for modeling passive microrheology. Within this work, Matlab scripts were created for the calculation of MSD from the simulation results, validation of the viscous model was performed on experimental data and elementary models for the simulation of the viscoelastic environment were also designed. Two different approaches were chosen for the design of these models, namely the use of rigid obstacles under the assumption of a discrete environment and a mathematical model assuming continuous environment. Data from the viscous model showed good agreement with the experimental results. The results of viscoelastic simulations are presented, and further possible development of these models is discussed. The continuous mathematical model is considered closest to modeling viscoelastic behavior because of a characteristic curvature that was observed in the evaluation of MSD.
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Hyaluronan effect on transdermal penetration of selected pharmaceutical substances
Ureš, Tomáš ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
This work deals with the transmittance of a family of non-steroidal anti-inflammatory drugs across biological membranes in combination with the use of hyaluronan. Hyaluronic acid (hyaluronan, HYA) is a linear polysaccharide formed from disacharide units containing N-acetyl-D-glucosamine and glucuronic acid. HYA is present in almost all biological fluids and tissues, so there is an assumption that could affect the penetration of substances through the skin. Standards were prepared by anti-inflammatory drugs in admixture with various concentrations hyaluronan and subsequently measured transmittance of such substances through the skin. Standards were applied to the skin obtained from pig auricle. The drug content was determined by HPLC.
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Preparation, characterization of trimethylchitosan and verification of its interaction ability with regards to variable charged ionic compounds
Bayerová, Zuzana ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The aim of this thesis is to study the interactions of trimethylchitosan with oppositely charged substances with regard to its potential biomedical use. A substantial step before the study of interactions was a successful synthesis of trimethylchitosan, which was subsequently confirmed by characterization of the final synthesis product using physico-chemical methods (infrared spectroscopy, elemental analysis, nuclear magnetic resonance). The result product was subjected to negatively charged interactions such as sodium dodecyl sulphate as a representative of the ionic surfactant, alginate as a natural polysaccharide representative and Chicago Blue as a representative of the anionic dye. The ability to interact with sodium dodecyl sulfate and alginate was demonstrated by the formation of hydrogels, which were subsequently characterized by mechanical viscosity tests using rheometric properties. The positive affinity of trimethylchitosan for organic dyes has been investigated in agarose-based support hydrogel matrices for changes in transport and barrier properties.
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Genesis of new ultra-fine particles of milling stock in the course of the mill exposure.
Kejík, Pavel ; Pekař, Miloslav (referee) ; Svěrák, Tomáš (advisor)
This work deals with the study of limestone and corundum dry milling using attritor-type stirred mill in a batch mode. There were stearin and polyethylene glycol used as surfactants and spherical shaped steel grinding elements used for the experimental part of the work. The main idea was to examine behavior of the selected grinding stock type within a long-term grinding forces exposure in selected conditions of ultrafine dry milling leading up to the submicron area. Characterization of samples was performed by laser granulometry, X-ray powder diffraction analysis, flame atomic absorption spectroscopy, objective color determination and electrokinetic potential measurement. Experimetaly measured data implies that in all cases there was a re-agglomeration of the grinding stock particles occurring, although in different stages of the disintegration process and in mutually various degree. The analysis results denote that a larger erosion of the crystal structures with the associated increase of the amorphous phase in the submicron particle size took place in the grinding stock.
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Utilization of various methods of porosimetry in investigation of internal structure of biopolymer hydrogels
Zahrádka, Jan ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
The main aim of the thesis was to select, optimize and test suitable methods for studying inner structure of hydrogel materials. The study of the size of pores with potential use in fundamental and applied research of these materials is the central focus of the thesis. Firstly, a literature search was done in order to collect basic information about usefulness of the individual methods. On the basis of this literature search, the experimental part of the work was divided into several steps. First, selected methods of conventional porosimetry (mercury intrusion porosimetry, BET analysis and DSC thermoporometry) were applied on reference porous materials and the results obtained by the individual methods were compared. The methods optimized with the use of these reference materials were then utilized in the analysis of porosity of model hydrogels based on polyvinyl alcohol. Based on the results of this analysis, the usability and benefits of the individual methods were discussed with respect to the sample preparation, time and financial demands, and also from the viewpoint of compliance of the determined pore sizes with the range of sizes declared for the physical PVA gels.
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Influence of polysaccharides on caffein absorption from beverages
Osecká, Karolína ; Márová, Ivana (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis was focused on investigation of the interaction between the polysaccharide sodium hyaluronan (HA) and the alkaloid caffeine (CAF). The reason why this thesis was focused on study of aqueous solutions of hyaluronan with caffeine is that presence of polysaccharide can slow down the realising from hyalurona-caffeine complex. At first, it was determined whether the photophysical properties of caffeine reacts in different polarity solvents. Based on these results was studied the interaction of caffeine and hyaluronan using the fluorescence. Emission and excitation spectra of caffeine were observed. The HA of molecular weight of 1.7 MDa were chosen for the study of the interactions with the caffeine of concentration the caffeine contained in coffee. The results of interaction that would result to influence the emission properties of CAF, not show. In acidic solutions leading to the formation of various shapes of HA and by centrifugation it was determined whether HA in this form interacts with CAF, which was shown to decrease the absorbance of the supernatant in the CAF. The solution and the mixtures were measured in four types of environment in hydrochloric acid solutions at different pH. The influence of constant addition of caffeine and the HA of molecular weights of 1.7 MDa with different concentrations in different acidic solutions. As a part of the work was to determine how hyaluronan behaves in strongly acidic solution. And then determine the pH in model gastric juices after intake of Coca Cola and Kofola. The obtained results can be used as for description of the behavior of caffeine in the presence of selected polysaccharide.
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Preparation and characterization of novel application forms of humic substances in combination with water sorbents
Nováčková, Táňa ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This bachelor’s thesis discusses an applicability of hydrogel forms-based composite materials of humic acids and commercial water sorbent. According to the literature review, methods of incorporation of humic acids into commercial sorbents of water under various conditions and the resulting materials were subsequently characterized. In the characterization, major attention was paid to the determination of the water content and the swelling characteristics. Preparation of the composite materials was directed to use their sorption abilities and ability to control the release of humic substances in agriculture.
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Interactions and aggregation in hyaluronan-aminoacid-surfactant systems
Venerová, Tereza ; Velebný, Vladimír (referee) ; Pekař, Miloslav (advisor)
The effect of native hyaluronan addition on CMC of excluded surfactants (Tween 20, BETADET THC 2, SDS, CTAT a CTAB) in physiological solution (0,15 M NaCl) has been investigated by fluoresence spectroscopy with Pyrene and Nile red as probes. The greatest influence on CMC has been observed in systems with cationic surfactant. System of cetyltrimethylamonnium bromid has been closely studied. Solubilization experiments with a hydrophobic dye Sudan red has been realized and aggregation number of this system has been determinated via fluorescence quenching with cetylpyridinium chloride as quencher and Pyrene as fluorescence probe. Addition of hyaluronan (native or hydrophobicaly modified) reduces aggregation number of system.
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