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Preparation and Characterization of Mixed Hydrogels Based on the System Hyaluronan-Albumin
Hájovská, Pavla ; Kráčalík, Milan (referee) ; Kalina, Michal (advisor)
This diploma thesis deals with preparation and subsequent characterization of albumin (BSA) and mixed hyaluronan-albumin (HA+BSA) hydrogels. The experimental characterization was based on the rheological measurements of the influence of ionic strength, pH and molar mass of HA on the gelation process and the properties of formed gels, as well as the time stability of these properties. Following object of the study was swelling of hydrogels in water and buffers with different pH value. Characterization was extended by thermal analysis, morphology description using scanning electron microscopy (SEM) and study of transport properties of hydrogels for selected model substance. Due to increasing ionic strength, the gel point was shifted towards higher temperature values and the resulting gels exhibited higher values of complex moduli. In case when pH was lower than isoelectric point of BSA, attractive electrostatic interactions between albumin and hyaluronan took place and the faster gelation occurred, compared to the case when pH was higher than isoelectric point of BSA. On the contrary, values of complex moduli increased with increasing pH. The gel samples prepared in the presence of low molecular weight HA reached higher values of complex moduli, compared to samples with the high molecular weight HA. Rheological properties of BSA gels were stable over time, whereas the mixed HA+BSA were characterized by significant decrease of complex moduli during the first three days of storage. Due to heating up to 100 °C, more than 80 % of the weight of studied samples was lost, as a result of water evaporation. Further heating of hydrogels, up to 250 °C, did not cause other changes associated with weight loss, in contrast with crystalline powder BSA, in which another weight loss at 220 °C was observed, as a result of the beginning degradation. Swelling studies, as well as SEM images, indicated higher crosslink density of BSA gels, compared to HA+BSA samples, which exhibited higher values of swelling ratio. The lowest values of equilibrium swelling ratio were observed at pH 4, which is close to the isoelectric point of albumin. Calculated diffusion coefficients relative to diffusivity of methylene blue in water ranged between the order of 10E-2 for diffusion into physiological solution and the order of 10E-3 for the diffusion into water. Ongoing transport of model dye from gel to solution was significantly slower, compared to its diffusion in water, as a result of gel porosity and electrostatic immobilization of positively charged molecules of methylene blue on the negatively charged BSA and HA chains.
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Resonance energy transfer in the environment of the hydrogel matrix
Janča, David ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
The diploma thesis deals with resonance energy transfer in hydrogel matrix enviroment. In the theoretical part, all the important features of these systems and their components are summarized and all the principles for explaining the method used are described. The work also includes a short literary background research. In the experimental part, the resonance energy transfer was measured in micellar solutions and hydrogels in 0.15 M NaCl medium. The hydrogels were formed on the basis of interaction of the surfactant with the oppositely charged polyelectrolyte. As a positively charged surfactant, carbethopendecinium bromide (Septonex) was chosen and hyaluronan as the negatively charged polyelectrolyte. Perylene with fluorescein and perylene were selected as fluorescent pairs for RET. It has been found that increasing concentration of the acceptor molecule increases the intensity of RET, in other word the rate of acceptor binding to the donor. In the study of fluorescent pair of perylene with DiO was observed, that it was not appropriate to use fluorescence probe DiO at higher concentrations. Experiments were carried out to determine whether RET changes in the time from the point of mixing the donor and acceptor fluorescence probes together. This phenomenon has not been confirmed. In hydrogels, the effect of increasing surfactant concentration and molecular weight of hyaluronan was observed. The resulting analysis showed that the molecular weight of hyaluronan has a significant effect on RET efficiency in hydrogels.
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Diffusivity of humic hydrogels
Král, Jan ; Smilek, Jiří (referee) ; Klučáková, Martina (advisor)
Presented diploma thesis focuses on the study of diffusion of cupric ions in humic acid gels. A total of fifth different standards of humic acids and one sample humic acid prepared from same source as in bachelor's thesis, on which this thesis continues, were used for preparation solutions of humic acids. Thereafter, these solutions were used for preparation of agarose hydrogels, which were necessary in following diffusion experiments. The objective of the work was to compare transport properties of humic standards between themselves and then compare standards with humic acid prepared from same source as in bachelor's thesis. Measure, which was used to determine the transport properties, was comparison of effective diffusion coefficients. Method of instantaneous planar source diffusion was used to compare them. This method was based monitoring temporal evolution of diffusion profiles of cupric ions in humic hydrogels. Copper ions were selected as diffusing medium because of their high affinity and strong bonds to humic acids.
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Biocompatibility and immunocompatibility of polymers for gene therapy
Matyášová, Veronika ; Šírová, Milada (advisor) ; Tučková, Ludmila (referee)
Gene therapy is a potential strategy for treatment of diseases caused by a gene defect. Recent studies are involved particulary in the cure of diseases caused by single gene defect (cystic fibrosis, haemophilia, muscular dystrophy etc.). Our work is part of a project aiming at developing ex vivo non-viral gene delivery systems that could be used for the treatment of ocular and cardiovascular diseases. The gene vectors are biodegradable polymeric carriers based on poly-α-amino acids. These polyplexes should transfect target cells which are supposed to be seeded on polyimide membranes. The biodegradable polymer membrane will be implanted into the retina or used as a coating for cardiovascular prosthesis. As a cover of the implantable membranes we used polymerized methacrylamide-modified gelatin forming hydrogels and mediating a growth support for transfected cells. We focus on material bio- and immunocompatibility/immunoacceptability. The results indicated a very good bio- and immunocompatibility of the gelatin B hydrogel both in vitro and in vivo. The gelatin B hydrogel did not cause erythrocytes lysis, stimulation of proliferation (spontaneous or mitogen-induced) of mouse or human lymphoid cells, neither production of cytokines or NO in vitro. Histological examination following subcutaneous...
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Thermosensitive polymer gels
Pelánová, Markéta ; Smilek, Jiří (referee) ; Chamradová, Ivana (advisor)
The presented thesis on thermosensitive polymer gel is focused especially on a thermosensitive triblock copolymer, which is composed of hydrophobic polylactide, polyglycolid and hydrophilic polyethylene glycol (PLGA-PEG-PLGA). Thermosensitive copolymers are very attractive for their phase sol-gel transitions and gel-suspension transitions. The aqueous solution of this copolymer behaves like a sol at laboratory temperature and like a gel at body temperature. These systems are used as injectable carriers for targeted drug delivery with controlled release. However, the influence of the resulting polymer concentration and temperature on the thermosensitive hydrogel nanostructure was not yet fully studied. In the experimental part, the viscoelastic behavior of hydrogels was observed by dynamic rheological analysis at different polymer concentrations and temperature conditions. The average size and distribution of micelles of triblock copolymer in aqueous solution were measured using dynamic light scattering technique. Characterization of fibrous micelles was complemented by imaging technique, cryogenic transmission electron microscopy.
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Využitie pomocných pôdnych látok pri zakladaní trávnikov
Petríček, Jozef
The literature review section of this thesis deals with the characteristics of types of lawns, and more about the methods of lawn making. Furthermore, in the thesis there is the description of natural and artificial soil conditioners. The thesis' experiment, which took place at the ZF MENDELU plots , consisted of landscaping, blown experimental plots, incorporation of Hydrogel and sowing seeds. The seeds used were either coated or uncoated seeds. The experiment consisted of 6 variants and each variant had three repetitions. The grasses rate of emergence, the amount of biomass after cutting and the depth of the root systems were tested on the sowed seeds. The fastest emergence and initial growth and the longest grass' length were observed in variant 3 in which seeds were coated with Hydro-absorbent and land applied with hydrogel at a dose of 50g.m2. Variant 3 also had the longest root system.
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Posouzení vhodnosti pěstebního substrátu s obsahem kokosových vláken
Kuncová, Lenka
The aim of the thesis was to verify the practical relevance and impact of nursery growing substrates containing coconut fiber development and quality produced by the trees. The experiment was based on the experimental area of the Horticultural Faculty in Lednice . The experiment was used ornamental tree Spiraea bumalda 'Anthony Waterer ' .
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Implants for nervous system
Kuruc, Lukáš ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This thesis deals with implants for nervous system. The first part of this thesis focuses on theoretical analysis of this issue, makes reader familiar with seriousness of spinal cord injury, its treatments options and regeneration with hydrogel implants. The second part describes experimental manufacturing of implants, testing patency and summary of their properties.
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A novel way of preparing hydrogels
Kratochvílová, Olga ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
This work is focused on testing the effect of ionic strength on the preparation of hydrogels prepared by phase separation hylauronanu polyelectrolyte solution (Hya) with cationic surfactant cetyltrimethylammonium bromide (CTAB) called „dry way“. In this case, there is a mixing of the polymer and the surfactant in the dry form and then added to the dispersion medium. With observation and rheology, the effects of the proportion of the components for the formation of the hydrogel. It was found that the higher the ionic strength causes the hydrogel has a lower viscosity and a more fluid. Tthis fact was confirmed from the results of rheological measurements. The gel with the ionic strength of 1 M is less viscous to gel the ionic strength of 0,5 M. Next, the purity of the hydrogel was observed, and it was found that hydrogels with the ionic strength of 0,15 M are clear without the use of centrifugation. In case of getting gel of the specific ionic forces of 0,15 M and 0,3 M formed by addition of multivalent cations/anions from observations we can say that the ionic strength in the case of the method of preparation of gels does not matter.
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Humic substances as transport medium for plant nutrition
Vlková, Markéta ; Solná, Irena (referee) ; Klučáková, Martina (advisor)
This bachelor thesis treats about humic matters and their application in agriculture by means of hydrogels transport medium. It studies progressive releasing of substances, which could be used as more common nutrition for plants, prepared from superabsorbent polymers. Research was implemented in collaboration with industrial partners. The substances are synthetically made of sodium Lignohumate and mixture of industrial fertilizer called NPK. Released substances were characterized by using some methods. First, there were measured qualities, which didn’t specify released compounds, like swelling, conductivity, pH and absorption of hydrogels with different wavelengths. More details came with methods ICP-OES and ion chromatography. Hydrogels which contained both mixtures of matters written up, were studied in water solution for 5 weeks and every week all characterization were measured. From the results we can see that both of the mixtures decrease ability of hydrogel’s swelling, mainly NPK. Measuring of absorption showed that the most of the substances released from sodium Lignohumate were from hydrogels without NPK. By other measuring, we noticed realizing of potassium and phosphorus elements. The most of them were from hydrogels containing NPK. By measuring ion chromatography, we found chloride, phosphoric, sulfuric and nitric ions in solution.
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