National Repository of Grey Literature 257 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Production of polyesters by extremophilic bacteria
Bednárová, Kristína ; Mravec, Filip (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis deals with the study of the production of polyhydroxyalkanoates using thermophilic bacterial strains Schlegelella thermodepolymerans, Schlegelella aquatica and Thermomonas hydrothermalis. The aim of the thesis is to optimize the conditions of polymer production. In bacterial strains of the genus Schlegelella, phaC gene at the genotype level was confirmed. The ability to produce polyhydroxyalkanoates in the bacterial strain Thermomonas hydrothermalis at the phenotype level was demonstrated. The utilization of selected carbon sources was studied experimentaly. The production of PHA was optimized by selecting the appropriate substrate and cultivation temperature. The effect of precursors on the production of copolymers P(3HB-co-4HB) and P(3HB-co-3HV) was observed. The most promising carbon substrate for bacterial strain Schlegelella aquatica was glycerol while the best metabolic activity was at 45 °C. Strain Thermomonas hydrothermalis was able to produce the copolymer P(3HB-co-4HB) with extreme high molar fraction of 4HB. Optimal cultivation temperature was 55 °C. The highest yield of P(3HB) among selected bacteria, synthesized Schlegelella thermodepolymerans cultivated on xylose at 55 °C. For this strain, the effect of aeration on biomass growth and PHA production was observed. In an effort to reduce production costs, Schlegelella thermodepolymerans was cultivated on model hydrolysates of lignocellulose-rich materials. Finally, batch cultivation in a larger production volume in laboratory fermentor was performed.
Application of microencapsulation techniques in development of novel controlled-release systems.
Karásková, Iva ; Mravec, Filip (referee) ; Sedláček, Petr (advisor)
This diploma thesis deals with application of microencapsulation techniques in development of hydrogel controlled-release systems in which the main role is played by humic acids, biopolymer chitosan, compound fertilizer NPK and 3-indoleacetic acid. This paper continues my bachelor thesis topic about utilization of polyelectrolyte complexes. The aim of this work was to develop a literature review focusing on the microencapsulation techniques and according to its results optimize the method. Microencapsulation was performed with a commercial encapsulator BUSCHI B-395 Pro and a release of individual components into a water was measured. An amout of released substances was measured by UV-VIS method and HPLC analysis. Practical part also included testing of repeated swelling and drying. It was found that suitable composition and combination of ingredients form hydrogels for further use in agriculture.
Kinetic study of excited state proton transfer in polymer-surfactant system
Bačová, Jana ; Vala, Martin (referee) ; Mravec, Filip (advisor)
In this bachelor thesis were studied interactions between hyaluronic acid and cationic septonex by steady-state and time-resolved fluorescence with fluorescence probes pyrene and 1-naphthol. At first was determined critical micelle concentration of septonex. In the case of both fluorescence probes was studied area below and above critical micelle concentration. It was found, that 1-naphthol undergo very fast deprotonation in aqueous solution, while in the present of micelles the rate of deprotonation is c significantly retarded. In the system of hyaluronic acid – septonex it was observed, that formation of aggregates occurs at lower concentrations than in the system without hyaluronic acid. Molecules of probe are probably distributed between hyaluronic acid – septonex aggregates and free micelles above critical micelle concentration.
Hydrogels with incorporated enzymes
Geistová, Karolína ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with the study of incorporation of enzymes into phase separated hydrogels. The aim of this work is to determine the enzyme activity in phase separated gels. Gels were prepared by the dry-way based on the interaction of negatively charged polyelectrolyte (hyaluronan) with positively charged surfactant (Septonex). Two enzymes, bromelain and collagenase, were incorporated into the hydrogels. To determine enzyme activity, the modified albumin protein with bound sulfanilamide group (azoalbumin) was used as a substrate. The enzyme activity of the enzyme itself, the enzyme activity affected by one of the two components of the system as well as the activity of the enzyme directly in the hydrogel was determined on UV-VIS spectrophotometry. The enzyme was found to be incorporated in the hydrogel. Furthermore, a significant effect of the positively charged surfactant on the enzyme activity was detected in phase-separated hydrogels.
Anisotropy techniques in study of cytoplasm
Sýkorová, Kateřina ; Obruča, Stanislav (referee) ; Mravec, Filip (advisor)
The main goal of this thesis was to compare experiments using time-resolved anisotropy and steady-state anisotropy for measuring in bacteria strain Cupriavidus necator. Fluorescent probe for anisotropy imaging was chosen BCECF_AM, which is derivate of fluorescein. Using experiment in system glycerol/water with fluorescein, anisotropy has been verified and calculated molecular hydrodynamic volume of a single fluorescein molecule, which approximately corresponded with real value. By using fluorescence imaging anisotropy microscopy, images and values of average anisotropy in cells were taken. Images of living cells (bacteria) of CN H16 and mutant CN PHB-4 showed differences, mainly in the uniformity of the inside environment.
Fluorescence correlation spectroscopy in colloid systems
Janíček, Tomáš ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
This work is focused on studying of stability and interaction in colloidal systems created by micelles of surfactant CTAB in solution of hyaluronic acid and water. As method chose for this work was selected fluorescence correlation spectroscopy. As dye was used Nile red. Measurements were divided firstly by size of polymeric chain and secondly by concentration of hyaluronic acid. Purpose of this work was to find out how will CTAB particles react with different sizes and concentration of hyaluronic acid. For comparison to hyaluronic acid was used Poly(sodium-4-styrenesulfonate).
Preparation and characterization of complex liposomal for drug delivery systems
Szabová, Jana ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with the preparation and characterization of stealth liposomes and their combination with trimethylchitosan (TMC). This complex could find application in the field of inhalation administration. Stealth liposomes were prepared from neutral phophatidylcholine, negatively charged fosfatidic acid and polyethyleneglycol bounded to phosphatidylethanolamine. We have managed to prepare stealth liposomes with suitable properties that should guarantee passive targeting without evocation an immune response, despite the content of the negative component. We also found a suitable method of preparation for stealth liposome–TMC complex, where the change of size and zeta potential confirmed the non–covalent bound between two components despite the content of the polyethyleneglycol.
Influence of the temperature on hydrophobic domain quality in a biopolymer-surfactant system.
Hnyluchová, Zuzana ; Kopuletá, Ema (referee) ; Mravec, Filip (advisor)
The temperature dependence on polarity has been investigated by fluorescence spectroscopy with pyrene as a probe. Pyrene was chosen thanks to its unique sensitivity to polarity of the medium. As a biopolymer was chosen 73 kDa and 1,4 MDa hyaluronic acid. Emission spectra of pyrene were measured as a function of temperature in aqous solution of CTAB in a presence and absence of sodium chloride. The results show, that the addition of specific concentration of hyaluronic acid to the sample with CTAB, mostly doesn´t have effect to change increasing/decreasing slope of polarity with the temperature.
Preparation of humic hydrogels for appliaction in cosmetics
Pavlicová, Renata ; Mravec, Filip (referee) ; Sedláček, Petr (advisor)
This bachelor´s thesis is focused on the preparation and characterization of hydrogels containing humic substances and assessment of their potential usefulness in cosmetic practice. Main objective of the work was to develop a literature review focusing on the potential use of humic substances in the cosmetics and pharmaceutical industries. Furthermore, the aim was to prepare model hydrogels addition of soluble humic substances in traditional cosmetic compositions and their characterization by basic methods of analysis parameters. The main investigated parameters were consistency resulting gels (assessed subjectively and subsequently by rheology), their internal pH and dry matter. The experimental results showed that incorporation of humic substances into hydrogels resulting gels acceptable characteristics for further use in cosmetic applications.
Preparation of model membranes to study their interactions with biopolymers using fluorescence correlation spectroscopy
Adamcová, Zuzana ; Márová, Ivana (referee) ; Mravec, Filip (advisor)
This diploma thesis is focused on preparation and characterization of supported lipid bilayers as simplified models of cell membranes. The bilayers were prepared from source system of lecithin liposomes in phosphate buffer using the vesicle fusion method on a cover glass sufrace hydrophilized by plasma. Three fluorescent probes – Nile red, Oregon Green DHPE and DiO – were utilized to characterize diffusion within the bilayer using fluorescence correlation spectroscopy. For this purpose Z-scan FCS, which is a method developed specially for planar samples, was used. After the process of preparation and characterization of supported lipid bilayer was optimalized, interaction between this artificial membrane and solution of hyaluronic acid in phosphate buffer was studied. It was found out, that addition of this biopolymer causes slowing the diffusion of the fluorescent probe within the bilayer.

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