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Hydrogels based on cationic polyelectrolytes
Jarábková, Sabína ; Lehocký,, Marián (referee) ; Pekař, Miloslav (advisor)
This diploma thesis deals with the study of physical hydrogels based on positively-charged polyelectrolyte. The study is to investigate the interaction of selected positively-charged polyelectrolytes with oppositely charged surfactants in water and in physiologicla saline solution (0.15 M NaCl). The influence of the process for preparing hydrogels. Hydrogels were prepared by dry or wet. Were tested solubilization abilities hydrogels prepared using the hydrophobic dye oil red O were also measured rheological properties of the hydrogels prepared using frequency oscillatory tests and flow tests, depending on the concentration of the polymer or surfactant. For the rheological experiments suggest that chitosan is capable of forming rigid hydrogels with better mechanical properties than the dextran in the presence of both surfactants. Selected samples were also carried out experiments using fluorescent sold prodan, nile red and -naphthol as fluorescent probes. And in selected experiments was determined by solids content in percentage depending on the concentration used polyelectrolytes or surfactants.
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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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Study of interactions of pigments with biopolymer chitosan
Kolesa, Pavel ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This master's thesis was focused on the study of interaction of some organic azo dyes (model diffusion probes) with cationic biopolymer chitosan. This interactions were realized via diffusion processes in hydrogel media based on thermoreversible agarose. The main aim was study of influence of pH of solution on the diffusion process. Interactions of used dyes are based on electrostatic character. The aminogroup of chitosan interacts with the functional group of chosen dyes (anionic sulfonic group) and thus affects the process of diffusion. The model diffusion compounds were chosen organic anionic dyes Chicago sky blue 6B (C.I. 24 410), Sirius red (C.I. 35 780) and Reactive blue 49 (C.I. 621 526). The important content of this diffusion method is a monitoring of the time progression of diffusion profile by UV-VIS spectrophotometry. The presented work follows the bachelor thesis and shows comprehensive view of the reactivity of chitosan and its behavior in different systems. Unsteady diffusion in cuvettes appears to be a universal method for the study of reactivity of biopolymers and for the study of transport processes in hydrogel media. The diffusion method is universal, easy and cheap.
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Preparation and characterization of hydrogels based on cationic biopolymer
Tesařová, Barbora ; Mravec, Filip (referee) ; Smilek, Jiří (advisor)
Presented thesis deals with the preparation and characterization of hydrogels based on positively-charged biopolymer and negatively-charged tenside. As an appropriate representative of positively-charged polymer was chosen chitosan, because of his biocompatibility and biodegrability, and N,N,N-trimethylchitosan, which was synthetised from chitosan in this diploma thesis. The final product of synthesis was characterised by SEC-MALS, elemental analysis, infrared spectroscopy and nuclear magnetic rezonation. Interactions between these polymers and representatives of negatively-charged tensides, which are sodium dodecylsuphate and sodium tetradecylsulphate, were investigated. The main method used in this thesis was rheology, through it were investigated prepared hydrogels based on chitosan and tensides and also prepared microgels based on N,N,N-trimethylchitosan and tensides. The interactions between polymers and tensides have been proved.
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Experimental study of artificial articular cartilage friction
Kulíšek, Vlastimil ; Ranuša, Matúš (referee) ; Rebenda, David (advisor)
Many conventional materials are used to replace damaged articular cartilage, which are beginning to be replaced by innovative biomimetic materials that mimic cartilage properties. One of these materials are poly(vinyl alcohol) (PVA) hydrogels crosslinked by freeze-thawing and cast-drying method. These hydrogels possess similar mechanical as articular cartilage. In order to clarify the effect of kinematic conditions on the friction of hydrogels, three levels of sliding speed and load and a uniform lubricant – PBS were chosen. The coefficient of friction of the FT hydrogel decreased with increasing load. The dependence of the sliding speed did not show a uniform trend and corresponded to the adsorption-repellent model for PVA gels. The coefficient of friction of the CD hydrogel increased with increasing sliding speed according to the repulsion-adsorption model for PVA gels. The increase in load at low sliding speeds of CD hydrogel caused a slight decrease in the coefficient of friction. At the highest speed, there was an optimal load at which a low coefficient of friction was achieved. The CD hydrogel showed a lower coefficient of friction than cartilage. The FT hydrogel achieved a lower coefficient of friction than cartilage only at 5 N and 10 mm s- 1. This work contributes to the understanding of the tribological properties of PVA hydrogels.
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Preparation and properties of agarose hydrogel with micellar domains
Sapárová, Alica ; Krouská, Jitka (referee) ; Pekař, Miloslav (advisor)
This diploma thesis was focused on the system of agarose hydrogels with micellar domains. Polysaccharide agarose was used for the preparation of hydrogel matrices. Septonex was chosen as a surfactant. The release of solubilizate from the agarose hydrogel matrix was studied with a hydrophobic dye Sudan III in order to obtain a model system of hydrophobic solubilized drugs. Sudan III was solubilized via surfactant´s micels. Subsequently, this micellar aqueous solution with the dissolved dye was used to prepare the agarose hydrogel. The system was prepared in the environment of deionized water and physiologic solution. The gradual release of the dye into deionized water and physiologic solution was studied for 22 days using the UV-VIS spectrophotometry method. It was found that after 14 days the concentration of the releasing dyes into the deionized water was decreased. The cause is that after 14 and 22 days there was a slight degradation of gels, which was detected using the rheology method. Using the rheology method it was also found that Septonex does not affect the gel formation process.
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Rheology of collagen hydrogels and its nanocomposites
Voldánová, Michaela ; Vojtová, Lucy (referee) ; Jančář, Josef (advisor)
This bachelor thesis deals with the phenomenological description of the rheological behavior of pure collagen I and its nanocomposites with addition of hydroxyapatite in four concentrations. Measurements were performed on a rheometer in the configuration cone – plate for a range of shear rates from 0 s-1 to 100 s-1 under defined conditions. At 4 °C, the collagen in samples of a specific composition remains dissolved; collagen retains his native character and the precursors of hydrogel are in the liquid state. By heating the aqueous solution of collagen with neutral pH leeds to spontaneous crosslinking process into fibrillar structure. At 37 °C, fibrils grow into the gel structure, however, the rate of its formation is dependent on the amount of collagen fibers. The measured data are processed in the form of flow and viscosity curves, from which the rheological behavior of the sample or structural and transformational changes in response to mechanical stress and temperature changes are evaluated and compared. This knowledge can be used to manipulate with hydrogels. Generally, it can help as a basis for further development of collagen, its interaction with HAP and factors influencing their stability or effectiveness.
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Diffusion of dyes in biopolymeric hydrogels
Vyroubal, David ; Mravec, Filip (referee) ; Klučáková, Martina (advisor)
This thesis is focused on diffusion of dyes in biopolymer-based hydrogels. These hydrogels are based on interaction between biopolymer-like electrolytes with oppositely charged surfactants. When polyelectrolytes interact with oppositely charged surfactants, micelle-like nano-containers can be formed. These nano-containers are able of binding hydrophobic compounds. In this study, combination of modified dextran (diethylaminoethyl dextran) with positive charge and oppositely charged sodium dodecylsulphate as surfactant was used for preparation of hydrogels. Next type of hydrogel was based on hyaluronan and positive charged surfactant Septonex (carbethoxypendecinium bromide). As a diffusion probes in hydrogels dyes Nile red and ATTO 488 were used. The diffusion of these dyes from aqeous solutions of NaCl or surfactants into hydrogels was monitored in time. Transport of dyes into structure of hydrogels was characterized by diffusion coefficients and structural parameters of hydrogels.
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Diffusion in humic gels.
Královič, Michal ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focuses on study of heavy metals diffusion in humic gels. The objective of the work was to verify, whether the diffusion is influenced by methylation of humic acid. Cupric and nickel cation was used in this thesis. Absorbance of solutions in acceptor and donor diffusion cell part was measured spektrofotometrically.
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Soil hydrogels based on the principle of controlled release
Macuráková, Viktória ; Smilková, Marcela (referee) ; Kratochvílová, Romana (advisor)
This bachelor thesis is focused on soil hydrogels, which operate on the principle of controlled release. The aim of the research was on the release of substances, and the practical use of hydrogels in agricultural practice. At work, we focused on the effect of humic substances and the quantities of the substances of the fertilizer NPK of hydrogel. Querying this data will use a variety of methods such as pH-metry, conductometry, spectrophotometry and chromatography and knowledge not only of the analysis but also the macromolecular chemistry. Experiment it was found that the content of sodium lignohumate does not affect the rate of release of potassium and phosphorus into the soil. Hydrogel which is located above the quantity of NPK fertilizer and a certain number of lignohumate released from its structures much larger amounts of ions such as Hydrogel without fertilizer NPK with approximately the same amount of lignohumate
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