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Rheological properties of modified polymer-composite bone pastes
Hlináková, Kristýna ; Vojtová, Lucy (oponent) ; Michlovská, Lenka (vedoucí práce)
Diploma thesis is focused on study of visco-elastic behavior of bone pastes based on calcium phosphate and the aqeous solution of biodegradable termosensitive triblock copolymer improving flowing properties of the paste. In the theoretical part, a brief characterization of calcium phosphate cements is elaborated. It also deals with the characteristics of rheological properties of injectable bone pastes. It includes a brief overview of additives influencing the rheological and mechanical properties of pastes. The experimental part was firstly focused on the triblock copolymer characterization by proton nuclear magnetic resonance spectroscopy and rheology. Secondly, the preparation of modified polymer-phosphate pastes was evaluated in terms of visco-elastic properties. Bone paste was modified by the addition of adhesive compouds (dopamine and sodium iodate) and antibacterial compound (selenium nanoparticles). Visco-elastic properties were performed by rheological analysis, during which the setting process proceeded exhibiting significant changes in the thixotropic behavior of both unmodified and modified phosphate pastes. The setting process took place at 23 °C and 37 °C imiting physiological environment. Morphology of polymer-phosphate pastes was characterized by scanning electron microscopy and the particle size was determined using a laser particle analyzer. It has been shown that the above-mentioned additives had a positive effect on the kinetics of self-setting paste process, moreover, selenium nanoparticles improved as well thixotropic behaviors of polymer-phosphate pastes. Therefore, novel injectable composite bone pastes are suitable for mini-invasive surgery in terms of treating fractures due to the adhesion additives as well as for osteomyelitis treatment due to the possible release of antibacterial nanoparticles.
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Catecholamine modified polymer-composite bone cement: preparation, characterization and in-vitro evaluation
Raszková, Alena ; Vojtová, Lucy (oponent) ; Michlovská, Lenka (vedoucí práce)
This bachelor thesis is focused on preparation, characterization of catecholamine-modified calcium phosphate cement and evaluation of in-vitro tests. The theoretical part deals with the characterization of calcium phosphate cements and their material property. This part also includes overview of additives used to modify cements in order to improve both their chemo-physical and biological properties. The increasing use of catecholamine in tissue engineering is also discussed here. First part of experimental work focuses on optimization of preparation and characterization of catecholamine modified calcium phosphate cement. The phase composition kinetics was evaluated by X-ray diffraction analysis and chemical composition by Fourier-transformed infrared spectroscopy. The second part of the work is then focused on the optimization and evaluation of in-vitro cytotoxicity of modified cements. In conclusion, it was found that the conversion rate during curing was faster when catecholamine was used to prepare phosphate cement. Modified cements exhibit almost 93 % conversion after 3 days with respect to unmodified one where the conversion reach only 79 % at the same time. For in-vitro testing, the new method for preparation of samples was approached. It was found that further optimization of the preparation method and test conditions are necessary for the successful in-vitro tests. Due to attractive properties, catecholamine-modified calcium phosphate cement seems to be an interesting material for bone regeneration.
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The effect of biopolymers on adhesive and rheological properties of calcium phosphate bone cements
Scholz, David ; Michlovská, Lenka (oponent) ; Vojtová, Lucy (vedoucí práce)
This thesis deals with bone cement composed of tricalcium phosphate and thermosensitive copolymer. The main aim was to improve especially the adhesive properties of the cement by adding polysaccharide. The theoretical part of the thesis deals with the characterization of bone cements and their application and also a description of polymeric additives used in bone cements mainly focused on polysaccharides. In the experimental part, the prepared cements were characterized using rheology, powder X-ray diffraction and static mechanical tests on the cured cement alone and glued bones. Rheology was used to measure the setting time of the cements as a function of time and temperature. Furthermore, rheology was also intended to measure the adhesive properties of copolymer solutions, but this was not possible due to the nonreproducible results caused by inhomogeneity of the copolymer solutions with polysaccharide. Powder X-ray diffraction was used to measure the effect of polysaccharide on the conversion of tricalcium phosphate to calcium deficient hydroxyapatite. It was found out that polysaccharide does not significantly affect the conversion of tricalcium phosphate. Static mechanical tests were used to measure maximal compressive strength for the cured cement samples and also to measure the adhesion strength of glued bone samples. Cured samples with low polysaccharide concentration showed higher compressive strength compared to control samples. Inconclusive results were obtained during testing of the bone samples due to the complexity of the measurement. In particular, it concerns the preparation of bone samples and their gluing with bone cement.
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Catecholamine modified polymer-composite bone cement: preparation, characterization and in-vitro evaluation
Raszková, Alena ; Vojtová, Lucy (oponent) ; Michlovská, Lenka (vedoucí práce)
This bachelor thesis is focused on preparation, characterization of catecholamine-modified calcium phosphate cement and evaluation of in-vitro tests. The theoretical part deals with the characterization of calcium phosphate cements and their material property. This part also includes overview of additives used to modify cements in order to improve both their chemo-physical and biological properties. The increasing use of catecholamine in tissue engineering is also discussed here. First part of experimental work focuses on optimization of preparation and characterization of catecholamine modified calcium phosphate cement. The phase composition kinetics was evaluated by X-ray diffraction analysis and chemical composition by Fourier-transformed infrared spectroscopy. The second part of the work is then focused on the optimization and evaluation of in-vitro cytotoxicity of modified cements. In conclusion, it was found that the conversion rate during curing was faster when catecholamine was used to prepare phosphate cement. Modified cements exhibit almost 93 % conversion after 3 days with respect to unmodified one where the conversion reach only 79 % at the same time. For in-vitro testing, the new method for preparation of samples was approached. It was found that further optimization of the preparation method and test conditions are necessary for the successful in-vitro tests. Due to attractive properties, catecholamine-modified calcium phosphate cement seems to be an interesting material for bone regeneration.
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Rheological properties of modified polymer-composite bone pastes
Hlináková, Kristýna ; Vojtová, Lucy (oponent) ; Michlovská, Lenka (vedoucí práce)
Diploma thesis is focused on study of visco-elastic behavior of bone pastes based on calcium phosphate and the aqeous solution of biodegradable termosensitive triblock copolymer improving flowing properties of the paste. In the theoretical part, a brief characterization of calcium phosphate cements is elaborated. It also deals with the characteristics of rheological properties of injectable bone pastes. It includes a brief overview of additives influencing the rheological and mechanical properties of pastes. The experimental part was firstly focused on the triblock copolymer characterization by proton nuclear magnetic resonance spectroscopy and rheology. Secondly, the preparation of modified polymer-phosphate pastes was evaluated in terms of visco-elastic properties. Bone paste was modified by the addition of adhesive compouds (dopamine and sodium iodate) and antibacterial compound (selenium nanoparticles). Visco-elastic properties were performed by rheological analysis, during which the setting process proceeded exhibiting significant changes in the thixotropic behavior of both unmodified and modified phosphate pastes. The setting process took place at 23 °C and 37 °C imiting physiological environment. Morphology of polymer-phosphate pastes was characterized by scanning electron microscopy and the particle size was determined using a laser particle analyzer. It has been shown that the above-mentioned additives had a positive effect on the kinetics of self-setting paste process, moreover, selenium nanoparticles improved as well thixotropic behaviors of polymer-phosphate pastes. Therefore, novel injectable composite bone pastes are suitable for mini-invasive surgery in terms of treating fractures due to the adhesion additives as well as for osteomyelitis treatment due to the possible release of antibacterial nanoparticles.
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