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Wound dressing nanofibers mats fabricated from nanocomposite material
Čileková, Marta ; Pavliňák,, David (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
New wound dressing based on nanocomposite polyvinyl alcohol/hyaluronan/ silver nanoparticles (PVA/HA/Ag-NPs) was prepared by green way. Hyaluronan was used as reducing and stabilizing agent for hyaluronan for silver nanoparticle preparation. Different parameters were investigated for preparation of Ag-NPs like concentration of silver nitrate as a source of Ag-NPs (0.01, 0.1, 0.5, 1M), concentration of HA (1, 2 %) and molecular weight of HA (50 kDA, 1,7 MDa). The nanofibers dressing sheet were fabricated by electro-spinning technique using different ratios between PVA and HA/Ag-NPs (100; 90/10; 80/20; 64/40; 50/50). The nanocomposites were evaluated by TEM, rheology, DLS, UV/Vis spectroscope, and the wound dressing nanofibers were characterized by SEM, TGA, FTIR, XRD and the mechanical properties were measured and evaluated.
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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 chitin film
Debnáriková, Michaela ; Abdelrahman, Rasha (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
The bachelor thesis deals with the extraction, purification, dissolution and preparation of film based on chitin/ polyvinyl alcohol (PVA). The pure chitin was fully characterized by different techniques like potentiometric titration, FT-IR, TGA, XRD, SEM and solid NMR. The solubility, purity of extracted chitin was investigated and evaluated by measuring the protein percent, rheology, and time need for dissolution. The chitin/PVA films were prepared using different ratio between chitin and PVA solution and film was prepared by casting method. The surface morphology, rheological and mechanical properties of the film were measured and evaluated.
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Novel hydrogels based on polysaccharides for soft tissue regeneration: preparation and characterization
Nedomová, Eva ; Abdellatif, Abdelmohsan (oponent) ; Vojtová, Lucy (vedoucí práce)
Presented diploma thesis deals with preparation, crosslinking and physico-chemical characterization of natural polysaccharide-based hydrogels. The aim of the work was to evolve elastic thin films with potential application for moist wound healing. The theoretical part summarizes the state-of-art about regeneration of soft tissues and their substitutes (synthetic or nature). There are pointed out the basic information about natural polysaccharide gums (chemical structure, solubility, heat and pH stability etc.), its modification and chemical crosslinking. The experimental part is focused on the modification of natural gum Karaya in order to make transparent hydrogels with adjustable hydrolytical stability. Samples were analyzed by FTIR, TGA followed by evaluation of swelling properties and hydrolytical degradation. Based on the results, chemical modification helped to stabilize polysaccharide hydrogels in water up to 25 days which is useful mainly for moist wound healing (e.g. after burns) because of high values of water uptake (from 85 up to 96%).
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Wound dressing nanofibers mats fabricated from nanocomposite material
Čileková, Marta ; Pavliňák,, David (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
New wound dressing based on nanocomposite polyvinyl alcohol/hyaluronan/ silver nanoparticles (PVA/HA/Ag-NPs) was prepared by green way. Hyaluronan was used as reducing and stabilizing agent for hyaluronan for silver nanoparticle preparation. Different parameters were investigated for preparation of Ag-NPs like concentration of silver nitrate as a source of Ag-NPs (0.01, 0.1, 0.5, 1M), concentration of HA (1, 2 %) and molecular weight of HA (50 kDA, 1,7 MDa). The nanofibers dressing sheet were fabricated by electro-spinning technique using different ratios between PVA and HA/Ag-NPs (100; 90/10; 80/20; 64/40; 50/50). The nanocomposites were evaluated by TEM, rheology, DLS, UV/Vis spectroscope, and the wound dressing nanofibers were characterized by SEM, TGA, FTIR, XRD and the mechanical properties were measured and evaluated.
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Preparation of chitin film
Debnáriková, Michaela ; Abdelrahman, Rasha (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
The bachelor thesis deals with the extraction, purification, dissolution and preparation of film based on chitin/ polyvinyl alcohol (PVA). The pure chitin was fully characterized by different techniques like potentiometric titration, FT-IR, TGA, XRD, SEM and solid NMR. The solubility, purity of extracted chitin was investigated and evaluated by measuring the protein percent, rheology, and time need for dissolution. The chitin/PVA films were prepared using different ratio between chitin and PVA solution and film was prepared by casting method. The surface morphology, rheological and mechanical properties of the film were measured and evaluated.
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Novel hydrogels based on polysaccharides for soft tissue regeneration: preparation and characterization
Nedomová, Eva ; Abdellatif, Abdelmohsan (oponent) ; Vojtová, Lucy (vedoucí práce)
Presented diploma thesis deals with preparation, crosslinking and physico-chemical characterization of natural polysaccharide-based hydrogels. The aim of the work was to evolve elastic thin films with potential application for moist wound healing. The theoretical part summarizes the state-of-art about regeneration of soft tissues and their substitutes (synthetic or nature). There are pointed out the basic information about natural polysaccharide gums (chemical structure, solubility, heat and pH stability etc.), its modification and chemical crosslinking. The experimental part is focused on the modification of natural gum Karaya in order to make transparent hydrogels with adjustable hydrolytical stability. Samples were analyzed by FTIR, TGA followed by evaluation of swelling properties and hydrolytical degradation. Based on the results, chemical modification helped to stabilize polysaccharide hydrogels in water up to 25 days which is useful mainly for moist wound healing (e.g. after burns) because of high values of water uptake (from 85 up to 96%).
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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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