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Study on structure and behavior of water in vicinity of hydrophilic surfaces
Slaninová, Eva ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
The main aim of the bachelor thesis was focused on study of the effect of hydrophilic surfaces on the structure and behavior of water. Especially, it deals with the new experimental findings with regard to the anomaly behavior of water in vicinity of hydrophilic surfaces where explore the formation of structured water in as it is called exclusion zones. Exclusion zones were studied along the hydrophilic surfaces (Nafion) and examined from the point of view of the kinetics of exclusion zone, the effect of addition of ions and polar compounds and study the structure of the hydrated Nafion using infrared spectroscopy.
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Study of surface tension of systems applied in ultrasonography.
Říkovská, Klára ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
Surface tension of sonography systems was investigated using several experiments. These experiments were comprised of measurements of surface tension using BPA-800P tensiometer. The influence of surface tension of commercial substance SonoVue®, which contains in its structure two types of phospholipids, was studied more detailed. Other phospholipids were studied to comparison with SonoVue®. All substances were dissolved in saline (0,15 M NaCl). Effect of gas type on microbubbles formation and surface tension was investigated. Some samples were studied using du Nüy ring method. It was found that gas constructing the microbubbles (air or SF6) has no impact to the surface tension value. Production of foam on the surface of solutions has an impact on the value of the surface tension. This foam degreases the surface tension. Gas pressure is significant to comparison of measured data.
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Analytical methods for hyaluronan
Černá, Lucie ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
This thesis deals with of simple methods for determining the concentration of hyaluronan in aqueous solution and compares the performance of each selected methods such as UV -VIS spectroscopy, IR spectroscopy and the method of determination by alcian blue. These methods were chosen for their simplicity and low cost of the assay. As the most reliable of these three methods, seems to be the method of IR spectroscopy. Determination of the concentration of HA by this method is relatively accurate at concentrations above 0.4 % in deionized water. The method of UV-VIS spectroscopy is based on a linear calibration curve determination, but no characteristic peak was detected, which means that this determination could be influenced by other components of the aqueous solution. Weak ionic strength and molecular weight of HA does not affect the determination. In the method with alcian blue, the results were quite unsatisfactory and does not correspond with the literature. Therefore, this method is not applicable in this form for determining the concentration of HA. Another option for determining the concentration of the HA is ELISA method. These are commercially produced kits suitable for determining low concentrations in low volumes. Its price is higher than the above- mentioned methods.
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Study on structural and thermodynamic aspects of the interactions of humic substances with organic ions.
Fryšová, Eva ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the study of thermodynamic and structural aspects of the interactions of humic acids with organic ions. Methylene blue (dye) was used as a model organic ion. The interactions were studied by isothermal titration calorimetry and dialysis in diffusion cells. The calorimetric experiments showed exothermic nature of the interactions. Furthermore it was proved that increasing concentration of humic acids causes increasing of reaction enthalpy. The dialysis experiments found that increasing concentration of humic acids causes increasing of apparent equilibrium constant. The value of this constant was lower for modified humic acid due to the reduced content of the binding sites.
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Use of selected fluorescence techniques to characterization of microbial cells
Vaněk, Martin ; Pekař, Miloslav (referee) ; Márová, Ivana (advisor)
Carotenoids are one of the most abundant natural pigment. Furthermore, they have great potential for wide industrial utilization. Nowadays, prefered (and cheaper) synthetic method counters progressively improved biotechnological production. Far more cheaper production should be reached via implementing methods of on-line optimization, such as flow cytometry. In this thesis the dependence of yeasts autotofluorescence intensity on carotenoids concentration in dry mass was studied. The dependence was established by means of linear regression. Moreover, the dependence between light scatter and the amount of dry mass was established by means of model utilizing forward scatter, side scatter and number of cells in unit volume. Yeasts' cells was also studied under the lenses of laser scanning confocal microscope. The goal was to localize carotenoids inside cells. Experiments undertaken suggest that they are localized inside the lipidic granules, but more experiments are required for a proof.
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Study of aggregation process and physical stability of polymeric micelle by fluorescence probe method
Chovancová, Romana ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
Amphiphilic block copolymer poly(ethylene glycol)-b-poly(–caprolactone) (PEG–PCL) was synthesized from poly(ethylene glycol) (PEG) and poly(–caprolactone) (PCL) by using ring-opening polymerization. The structure and composition of this copolymer was determined by IR spectroscopy. Polymeric micelles were prepared by membrane dialysis method and direct dissolution of copolymer in water. The process of aggregation and physical stability in water solution was studied by fluorescence spectroscopy using pyrene and perylene as fluorescent probes.The results of steady-state and time resolved fluorescence measurements indicate that system of PEG–PCL forms both unimolecular and multimolecular micelles, which depends on copolymer concentration. The critical micelle concentration (CMC) was around 0,002 g/L. Measurement of micelles size by dynamic light scattering method suggested that systems with higher concentration form bigger aggregates. In addition, copolymer behavior was explored under physiological conditions. The results show that CMC of copolymer increased in 0,15 mol/L sal solution at temperature 37°C to 0,02 g/L when compared to copolymer in water.
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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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Optimalization of experimental method for study on penetration of humic acids into leaves.
Smilková, Marcela ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This bachelor’s thesis is focused on the study of penetration of humic substances trough the plant cuticle. The main objective of the thesis aimed at a literature search on foliar fertilization and transport of substances in the plant leaves. According to the literature search, experimental technique was suggested and tested in order to study penetration of humic substances through the leaf cuticle. The method consists of observation of diffusion transport of humic acids between two inert agarose gels separated by the plant cuticle. Cuticles were prepared by the means of three different isolation procedures.
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Aggregation processes in amphiphil-polymer system
Šejnohová, Michaela ; Márová, Ivana (referee) ; Pekař, Miloslav (advisor)
This Bachelor´s thesis is focused on the exploration of polyelectrolyte-surfactant system by fluorescence spectroscopy with pyrene as fluorescent probe. Cationic cetyltrimethylammonium bromide (CTAB) was used as a surfactant. Native hyaluronan was used as polyelectrolyte. Hyaluronan was used in one constant molecular weight and one constant concentration. The whole system was prepared in an aqueous environment. Interactions were studied in area between critical aggregation concentration (CAC) and critical micelle concentration (CMC). The influences of the concentration of pyrene and the effect of the way of the samples preparation on aggregation behavior were also studied. It was found that above the critical aggregation concentration exists an area where stable properties of aggregates can be found. The concentration of pyrene has a major effect on the fluorescence properties of the system. Preparation of samples affects the aggregation of the system. At higher surfactant concentrations, above the stable area, was observed phase separation and gel formation.
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Encapsulation of caffeine
Patočková, Klára ; Pekař, Miloslav (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on possibilities of encapsulation caffeine in micro- and nanoparticles. In the theoretical part was devoted to information about caffeine, liposomes and polysaccharides and also on the techniques of encapsulation. In the experimental part 5 different methods were used for preparation of micro- and nanoparticles with encapsulated caffeine. Caffeine was packaged into liposomes and polysaccharide particles (chitosan/alginate). Encapsulation’s effectiveness was determined by HPLC/UV-VIS. Prepared particles were monitored for size and stability by dynamic light scattering. The particles were exposed to the arteficial stomach and intestinal juices and bile acids. Particle stability and amount of released caffeine was monitored. Analytical centrifugation was used to measurement of sedimentation velocity and stability of the prepared particles. Caffeine containing particles were added in several soft drinks to determine particles amount when turbidity occurred.
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