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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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Kinetics Studies of Collagen I Self-Assembly
Voldánová, Michaela ; Ondreáš, František (referee) ; Jančář, Josef (advisor)
Collagen, the most abundant protein of connective tissues, in various forms has a wide applications due to their diverse biological and chemical properties. One of the forms are collagen hydrogels, which are considered very suitable material for applications in tissue engineering, because they are able to provide biodegradable scaffolds that its properties correspond with living tissues. These systems are used for example as scaffold for targeted drug delivery with controlled release, in combination with cells can be used for the regeneration and reconstruction of tissues and organs. Heating the aqueous solution of collagen leads to spontaneous self-assembly process to variously distributed fibrillar structures, which are at a later stage of fibrillogenesis prerequisite for creating a three-dimensional supporting network, which is the basic building block of the gel. The resulting properties of the hydrogel depend not only on its structure, but also on the conditions which cause self-assembly process. Hydrogels were performed at 37 ° C and physiological pH. Studied structural variable was the concentration of collagen. So far, for the research of self-assembly were used spectrometric methods, which only provide information about kinetics of morphogenesis. In this work to study the kinetics of collagen I self-assembly were used rheological methods, which additionally give information about viscoelastic properties of the resulting material. The obtained experimental data confirmed two-step process of collagen I fibrillogenesis consisting of nucleation and growth process. Rheological hydrogels collagen behaved as a nonlinear yield-pseudoplastic. An attempt was made to molecular interpretation of the results. Using two-parametric Avrami equation was determined the rate of self-assembly for each concentration of collagen and the value of Avrami exponent determining the shape of produced units. The prepared hydrogels were subjected to increasing shear stresses (strain amplitude, shear rate). Larger amplitudes leads to collapse of the hydrogel structure, which is able to again partially regenerated.
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Kinetics Studies of Collagen I Self-Assembly
Voldánová, Michaela ; Ondreáš, František (referee) ; Jančář, Josef (advisor)
Collagen, the most abundant protein of connective tissues, in various forms has a wide applications due to their diverse biological and chemical properties. One of the forms are collagen hydrogels, which are considered very suitable material for applications in tissue engineering, because they are able to provide biodegradable scaffolds that its properties correspond with living tissues. These systems are used for example as scaffold for targeted drug delivery with controlled release, in combination with cells can be used for the regeneration and reconstruction of tissues and organs. Heating the aqueous solution of collagen leads to spontaneous self-assembly process to variously distributed fibrillar structures, which are at a later stage of fibrillogenesis prerequisite for creating a three-dimensional supporting network, which is the basic building block of the gel. The resulting properties of the hydrogel depend not only on its structure, but also on the conditions which cause self-assembly process. Hydrogels were performed at 37 ° C and physiological pH. Studied structural variable was the concentration of collagen. So far, for the research of self-assembly were used spectrometric methods, which only provide information about kinetics of morphogenesis. In this work to study the kinetics of collagen I self-assembly were used rheological methods, which additionally give information about viscoelastic properties of the resulting material. The obtained experimental data confirmed two-step process of collagen I fibrillogenesis consisting of nucleation and growth process. Rheological hydrogels collagen behaved as a nonlinear yield-pseudoplastic. An attempt was made to molecular interpretation of the results. Using two-parametric Avrami equation was determined the rate of self-assembly for each concentration of collagen and the value of Avrami exponent determining the shape of produced units. The prepared hydrogels were subjected to increasing shear stresses (strain amplitude, shear rate). Larger amplitudes leads to collapse of the hydrogel structure, which is able to again partially regenerated.
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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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