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Crosslinking of polysaccharide microfibers
Svidroňová, Barbora ; Abdellatif, Abdelmohsan (oponent) ; Vojtová, Lucy (vedoucí práce)
The general goal of the proposed diploma work was preparation and characterization of crosslinked hyaluronan microfibres, which would be stable in aqueous environment with proper mechanical properties. The fibres prepared by the wet spinning technique, were crosslinked with solution containing crosslinking reagent 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide or two crosslinking reagents, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide, leading to amidation and formation of ester bonds. Characterization of prepared samples is the main goal of experimental part of the thesis. The swelling characteristics were carried out to determine the stability of fibres in three different solutions (with pH 7.4, 3 and 11). For determination of thermal stability was used thermogravimetrical analysis, and for determination of esterification and amidation was used infrared spectroscopy with Fourier transformation. Mechanical properties of fibres were studied by stress-strain tester. Additionally, the rheological properties were investigated, as well as the microstructure and surface of fibres by scanning electron microscopy. The fibres before chemical crosslinking had lower stability in all three types of solutions; the thermal stability was also lower, than the stability of crosslinked fibres. For not chemically modified fibres with crosslinking reagent, only one type of peak for esterification occurred. The infrared spectra of chemically crosslinked fibres showed the presence of two esterification peaks, which was the result of the effectiveness of the crosslinkig reagent. Amidation was also stronger for crosslinked fibres, especially for fibres crosslinked long time and in the solution with higher concentration of crosslinking reagent. Due to the heterogeneity of fibres, mechanical properties did not show evidence of any dependence on the crosslinking. The rheological study showed that the viscosity of fibre dissolved in water is less dependent on the shear rate than the powder of sodium hyaluronan dissolved in water. Despite more different methods of characterization of fibres which were used in this work, there are still many options for better characterization and closer understanding of this biopolymeric material.
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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (oponent) ; Přikryl, Radek (vedoucí práce)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Microfibers based on polyhydroxybutyrate for medical applications
Gregušková, Zuzana ; Obruča, Stanislav (oponent) ; Přikryl, Radek (vedoucí práce)
Master’s thesis targets microfibers based on biopolymer poly(3-hydroxybutyrate) and their use in medical applications. The theoretical part deals with a study of the microfibers creation process using the technology of centrifugal spinning, its kinetics and factors influencing the creation and properties of prepared microfibres. Subsequently, the theoretical part orientates on a short overview of biopolymers used in the technology, characterization of material poly(3-hydroxybutyrate). It also presents a proposal of a potential target application of the microfibres. The experimental part concentrates on microfibers preparation from the mentioned poly(3-hydroxybutyrate). Several parameters leading to better spinnability of the material are tracked and optimized. The practical part is extended by modifying the polymer solution by adding other biopolymers and plasticizers and producing microfibres from the polymer mixture thus treated. Attention is also paid to the optimization of process parameters. Moreover, the prepared microfibres are analyzed and characterized by several methods and compared to develop a suitable alternative to currently used substrates for cell growth in 3D.
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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (oponent) ; Přikryl, Radek (vedoucí práce)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Microfibers based on polyhydroxybutyrate for medical applications
Gregušková, Zuzana ; Obruča, Stanislav (oponent) ; Přikryl, Radek (vedoucí práce)
Master’s thesis targets microfibers based on biopolymer poly(3-hydroxybutyrate) and their use in medical applications. The theoretical part deals with a study of the microfibers creation process using the technology of centrifugal spinning, its kinetics and factors influencing the creation and properties of prepared microfibres. Subsequently, the theoretical part orientates on a short overview of biopolymers used in the technology, characterization of material poly(3-hydroxybutyrate). It also presents a proposal of a potential target application of the microfibres. The experimental part concentrates on microfibers preparation from the mentioned poly(3-hydroxybutyrate). Several parameters leading to better spinnability of the material are tracked and optimized. The practical part is extended by modifying the polymer solution by adding other biopolymers and plasticizers and producing microfibres from the polymer mixture thus treated. Attention is also paid to the optimization of process parameters. Moreover, the prepared microfibres are analyzed and characterized by several methods and compared to develop a suitable alternative to currently used substrates for cell growth in 3D.
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Crosslinking of polysaccharide microfibers
Svidroňová, Barbora ; Abdellatif, Abdelmohsan (oponent) ; Vojtová, Lucy (vedoucí práce)
The general goal of the proposed diploma work was preparation and characterization of crosslinked hyaluronan microfibres, which would be stable in aqueous environment with proper mechanical properties. The fibres prepared by the wet spinning technique, were crosslinked with solution containing crosslinking reagent 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide or two crosslinking reagents, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide, leading to amidation and formation of ester bonds. Characterization of prepared samples is the main goal of experimental part of the thesis. The swelling characteristics were carried out to determine the stability of fibres in three different solutions (with pH 7.4, 3 and 11). For determination of thermal stability was used thermogravimetrical analysis, and for determination of esterification and amidation was used infrared spectroscopy with Fourier transformation. Mechanical properties of fibres were studied by stress-strain tester. Additionally, the rheological properties were investigated, as well as the microstructure and surface of fibres by scanning electron microscopy. The fibres before chemical crosslinking had lower stability in all three types of solutions; the thermal stability was also lower, than the stability of crosslinked fibres. For not chemically modified fibres with crosslinking reagent, only one type of peak for esterification occurred. The infrared spectra of chemically crosslinked fibres showed the presence of two esterification peaks, which was the result of the effectiveness of the crosslinkig reagent. Amidation was also stronger for crosslinked fibres, especially for fibres crosslinked long time and in the solution with higher concentration of crosslinking reagent. Due to the heterogeneity of fibres, mechanical properties did not show evidence of any dependence on the crosslinking. The rheological study showed that the viscosity of fibre dissolved in water is less dependent on the shear rate than the powder of sodium hyaluronan dissolved in water. Despite more different methods of characterization of fibres which were used in this work, there are still many options for better characterization and closer understanding of this biopolymeric material.
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