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Use of microcalorimetry in the study of hydration of biopolymers
Bola, Tomáš ; Smilek, Jiří (referee) ; Krouská, Jitka (advisor)
This master thesis deals with the using of microcalorimetry in the study of hydration of biopolymers. Lactose has been selected together with the other biopolymers although it is not among biopolymers but disaccharides. Selected biopolymers are alginate, dextrane, chitosan and hyaluronan of two molecular weights. Lactose has been selected for these purposes mainly because it is a model example to determine whether or not the reaction to moisture between the other samples and the saturated salt solution occurs. The biopolymer hydration study, as opposed to the commonly used perfusion calorimetry method using the possibility of measuring with adjustable moisture has been used an isothermal microcalorimetry method where at two constant temperatures the reaction of the sample to the different moisture released by the saturated salt solution was monitored.
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Preparation and characterization of hybrid hydrogels matrix
Magera, Lukáš ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
Submitted bachelor’s thesis aims for preparation and subsequent optimisation of hybrid hydrogels, which represent material with high application potential because of their unique properties. Hybrid hydrogels have extraordinary mechanical resistance and other beneficial properties (e.g. transportation) due to their unique hybrid network structure, strong interpenetrating network entanglement and efficient energy dissipation system. This work engages in chemically-physically crosslinked hybrid gel, namely the combination of alginate-polyacrylamide. The hybrid hydrogel was formed and then underwent the tests of drying and swelling. The main purpose of the experimental part was to determine viscoelastic properties of hybrid hydrogels using standard oscillation tests. Swelling tests showed that the hybrid network containing limitedly swelling alginate gel reaches lower degree of swelling than the single unlimitedly swelling polyacrylamide gel. Viscoelastic tests unveiled an influence on the mechanical properties by value augmentation of the hybrid gel´s storage modulus in comparison with the reference alginate hydrogel. Hybrid hydrogel reported an increase in the linear viscoelastic area compared to the reference polyacrylamide gel, whose hybrid structure prevents from creating microcracks, that caused earlier rupture of the reference polyacrylamide gel.
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Study of barrier and transport properties of polyelectrolytes using diffusion techniques in hydrogels
Valentová, Kristýna ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
This diploma thesis was focused on study of barrier and transport properties of selected polyelectrolytes in hydrogel matrices by using diffusion techniques. The study of these properties was performed in horizontal diffusion cells where is observed the change in diffusion probe concentration over time. Diffusion experiments were performed on an agarose hydrogel with the addition of alginate, hyaluronic acid, polystyrene sulfonate, humic acids and as a model probe rhodamine 6G was used. Important parts of this thesis are also the methods which characterize the substances and hydrogel matrices such as rheology and potentiometric titration. The main aim of this diploma thesis was to investigate the effect of interactions between passing model dye (rhodamine 6G) and the appropriate gel (agarose + polyelectrolyte) on the fundamental diffusion parameters (effective diffusion coefficient, lag time, etc.).
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Preparation and characterization of enzyme-containing wound dressings
Jurová, Bronislava ; Szotkowski, Martin (referee) ; Skoumalová, Petra (advisor)
This diploma thesis is focused on the study and characterization of nanofiber wound dressings from natural biopolymers. Proteolytic enzymes, specifically collagenase and bromelain, were incorporated into these nanofiber covers. The theoretical part deals with a brief description of skin wounds, their healing and skin covers. There are also methods for preparing these covers and the methods used to characterize them. The practical part deals with the optimization of the preparation of nanofiber coatings based on polyhydroxybutyrate, gelatin, alginate and chitosan. These nanofibers were then enriched with active substances and their gradual release into the model environment was monitored. Finally, their proteolytic activity was determined for these substances.
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Phospholipids as the basis of biodegradable delivery systems
Burdíková, Jana ; Čeppan, Michal (referee) ; Mravec, Filip (advisor)
This thesis is focused on investigation of phospholipid-hyaluronan system. First, appropriate method for preparation of bulk solution of phospholipid/lipid and suitable fluorescence probe were chosen. Sonification was selected as a method for preparation of bulk solution and pyrene was chosen as a fluorescence probe. From the group of phospholipids lecithin was selected. Next to phospholipid, lipid with no phosphate group (DPTAP) was utilized for comparison, alternatively a mixture of lipid (DPTAP) and phospholipid (DPPC). Instead of hyaluronan another polyelectrolytes (sodium polystyrene sulfonate, sodium alginate) were used too. Measurements were performed in water environment and in phosphate buffer saline (PBS). All investigation was accomplished by fluorescence spectroscopy and dynamic light scattering.
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The Utilization of Light Scattering Techniques for the Study on Hydrogel Gelation
Candráková, Simona ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This bachelor thesis focuses on the study of hydrogel gelation using light scattering methods. For these purposes two different biopolymers (agarose and sodium alginate), with different sol to gelation phase transition, were selected. In the case of agarose, the gelation is caused by temperature change. On the other side, the gelation of sodium alginate is initiated by addition of polyvalent cations. In the experimental part of the work, agarose gelation was studied by DLS, temperature gradients of agarose solutions (40 – 30 °C) were measured. During the measurement the particle size distributions in the solutions having different concentrations were monitored as well as the temperature influence on the diffusion coefficient. The DLS method provided the values of the gelling temperatures of the solutions at a concentration of 0,5 wt.% and 1,0 wt.%. Furthermore, the DLS microrheology method was used, where temperature dependences of viscoelastic characteristics of agarose solutions (40 – 30 °C) were also measured, from which the gelling temperatures of agarose solutions of 0,1 wt.% and 0,5 wt.% were evaluated. The classical rheology was also used in the work to compare the viscoelastic behaviour of the samples and to determine the gelation point of the agarose solutions. By this method were determined gelling temperatures for all studied concentration of agarose (0,1 wt.%, 0,5 wt.% and 1,0 wt.%). The DLS method was also used to monitor the interactions of sodium alginate with the addition of Ca2+ ions, these interactions were then also evaluated and discussed in the experimental part.
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Mechanical and Transport Properties of Hybrid Hydrogel Systems
Klímová, Eliška ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
This master´s thesis deals with the study on mechanical and transport properties of hybrid hydrogel systems. Considering applications of hydrogels, especially in chemical industry, pharmacy, or eventually medical applications, for the study gellan and alginate-based hydrogels were selected. In order to compare individual characteristics physical and hybrid hydrogels were prepared. Gellan hydrogels were prepared in deionization aqua solution, calcium chloride dihydrate and tween 80 solution. Alginate hydrogels were prepared in calcium chloride dihydrate solution as well, and polyacrylamide with N,N´–methylenbisacrylamide. For the study of mechanical properties moisture analyser and rheology measurements were selected. Transport properties were studied using the diffusion experiments combined with UV-VIS spectroscopic detection. Concluding of this thesis is summarization of measured values, which provides comprehensive review of the problematics. It was discovered that the conveniently selected concentrations of structural components of hydrogel matrix and the additives can influence both the mechanical as well as the transport properties of studied hydrogels.
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Encapsulation of selected natural extract for food application.
Vyskočilová, Terezie ; Kočí, Radka (referee) ; Márová, Ivana (advisor)
This diploma thesis deals with encapsulation of natural extracts. In the theoretical part the methods of encapsulation, materials for particle preparation, as well as application of encapsulation techniques in food industry were described. In experimental part selected natural extracts of propolis, green barley and probiotics were characterized. There substances were encapsulated into alginate and chitosan. In the total of 25 types of prepared particles long-term stability in some model physiological conditions as well as in four different model foods was evaluated. Additionally, stability of selected particles in several real milk-based products was followed too. The stability of particles was determined spectroptohometrically. In natural extract a content of polyphenols, proteins, chlorophylls, as well as total antioxidant activity were analysed. To analysis of probiotics optical and fluorescence microscopy were used. In propolis and green barley antimicrobial activity was tested too. Moreover, in the sample of propolis also cytotoxic assay was applied. Agar-chitosan was chosen as the best shell material for propolis due to its optimal stability in model physiological conditions as well as model foods. Liposomes were evaluated as unstable and were not recommended for further application. As the suitable shell material for powdered green barley starch-alginate (rate 1:4) and agar-chitosan were proposed, while the second one showed better stability for released proteins. Agar-chitosan shell material was usable for fresh green barley too. For probiotics encapsulation alginate or alginate-starch were chosen because of their porosity and possibility of nutrients diffusion. In real foods the best results were reached with application of probiotic particles into milk. Coencapsulation of powdered barley and probiotics did not confirm inhibition of culture growth. Neither the antimicrobial effect of propolis and barley nor the cytotoxic effect of propolis were confirmed.
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Encapsulation of active substances into nanofibers and possibilities of their application
Procházková, Lucie ; Pernicová, Iva (referee) ; Skoumalová, Petra (advisor)
The master thesis was based on the optimization of the production of nanofiber covers and to gaine the product for subsequent functional use. The production of nanofiber covers was made by electrospinning and forcespinning from selected materials. Polyhydroxybutyrate, gelatin, chitosan and alginate were used as starting materials. After successful optimization, these materials were enriched with active ingredients ampicillin and ibuprofen for the functionalized use of covers for more effective wound healing. The theoretical part was focused on the issue of skin, healing processes, types of wounds and nanofibers, the characterization of selected starting materials for the formation of nanofibers was also mentioned. The practical part was based on the lengthy optimization of the preparation of fiber covers and later enriched with active ingredients. Furthermore, combined covers made of different materials with contents of both active ingredients were designed. This was followed by the characterization of all prepared covers from the point of view of stability in the short and long term. The gradual release of active ingredients was determined spectrophotometrically and by hifh performance liquid chromatography. It was also important to determine the antimicrobial activity of selected active substances. At the end of all testing, combined coatings containing both active ingredients were used for safety testing with human keratinocyte cells (HaCaT). Safety testing was based on determining the viability of human cells using the MTT test, to verify the LDH test. A scratch test was also performed, a wound healing test after the application of devised combined covers.
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Development and characterization of hydrogel carriers for modern agricultural applications
Mai, Thuy Ha ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The bachelor thesis is focused on characterization of hydrogel carriers and their application in agriculture. Entrapment of active phase within the hydrogel matrix would allow release of its content in controlled rate. The theoretical part describes encapsulation techniques and suitable biocompatible materials involved in encapsulation. For the experimental part, the release of soil bacteria Cupriavidus necator H16 from alginate matrix was examined. The focus was on the release rate of bacteria via diffusion and later, on the release rate of bacteria encouraged by chemical or enzymatic reagents. Further modification of carrier was suggested by adding hydrophobic barrier composed of polyhydroxybutyrate (PHB). The modified alginate beads seemed to be more resistant toward enzymatic or chemical agents, thus the process of the release was to some extent suppressed. This fact might suggest PHB as a possible vessel for optimization of controlled release system of hydrogel carriers.
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