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Study of degradation of biocompatible copolymers
Oborná, Jana ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
This diploma thesis is focused on biocompatible polymers degradation study. Copolymers were studied based on poly(lactic-co-glycolic) acid and poly(ethylene glycol) PLGA-PEG-PLGA and further these copolymers modified with itaconic acid ITA-PLGA-PEG-PLGA-ITA. This paper investigated the influence of pH phosphate solution on the degradation of polymers. Degradation of polymers occurred at 37 °C in phosphate solution with pH 4.2, 7.4 and 9.2. High performance liquid chromatography with UV-VIS detection of diode-array type was used for quantitative determination of lactic acid and glycolic acid as the final degradation products. For qualitative identification of additional degradation products were used tandem connection liquid chromatography and mass spectrometry. Gel permeation chromatography with refractive index detector was used to determine the molecular weight decrease polymer chain after the degradation.
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Controlled Drug Release from Biodegradable Hydrogels.
Oborná, Jana ; Chýlková, Jaromíra (referee) ; Kráčmar, Stanislav (referee) ; Kučerík, Jiří (referee) ; Vávrová, Milada (advisor)
This dissertation is focused on the controlled release of drugs from a biodegradable amphiphilic hydrogel based on hydrophobic poly(lactic acid), poly(glycolic acid) and hydrophilic poly(ethylene glycol) (PLGA-PEG-PLGA, ABA) and its modification with itaconic anhydride (ITA). The resulting ,-itaconyl(PLGA-PEG-PLGA) copolymer is referred to as ITA/PLGA-PEG-PLGA/ITA or ITA/ABA/ITA. Itaconic acid provides reactive double bonds and a functional carboxyl group at the ends of the PLGA-PEG-PLGA copolymer chain, thereby rendering the modified ITA/ABA/ITA copolymer less hydrophobic and offering the possibility of forming a carrier for hydrophilic drug substances. These functional copolymers are thermosensitive and change in the external environment (e.g. temperature) causes a sol-gel phase transition due to the formation of micellar structure. The bioactive substances can thus be mixed with a copolymer which is in a low viscous phase (sol phase) and subsequently the mixture can be injected into patient's body at the target site where it forms a gel at 37 °C. This hydrogel becomes a drug depot, which gradually releases the active substance. Prediction of the substance’s release profile from the hydrogel is an effective tool to determine the frequency of administration, potentially enhancing efficacy, and assessment of side effects associated with dosing. The analgesic paracetamol and the sulfonamide antibiotic sulfathiazole were used as model drugs, representing hydrophilic and hydrophobic substances, respectively. The active substances had a significant effect on the resulting hydrogel stiffness. Type of solvent, incubation medium and nanohydroxyapatite also influenced on the gel stiffness and subsequent stability of the hydrogel-drug system. Controlled release of drugs took place in simulated conditions of the human body. Verification of Korsmeyer-Peppas (KP) drug-release model is also discussed in this thesis. The KP model was found suitable for simulating the release of sulfathiazole from ABA and ITA/ABA/ITA hydrogels. On the contrary, the performance of KP model was not suitable for describing the release of paracetamol from the ABA hydrogels. Therefore, a new regression model suitable for both buffered simulated media and water has been proposed. The proposed model fitted better the release of both sulfathiazole and paracetamol from composite material prepared from ABA hydrogel and nanohydroxyapatite.
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The issue of penicillin antibiotics in water
Landová, Pavlína ; Oborná, Jana (referee) ; Vávrová, Milada (advisor)
This bachelor thesis deals with the occurrence and determination of penicillin antibiotics in wastewater. Penicillin V was selected as a representative of this class of antibiotics due to its frequent prescribing. Solid phase extraction (SPE) was selected as a method of isolation of the analyte from the wastewater. Optimal conditions were found for Bakerbond C18 SPE column. Drug analysis was carried out on ultra-high performance liquid chromatography (UHPLC) with diode array detection (UV-VIS/DAD). Under optimized conditions, the analysis of wastewater from the WWTP Brno Modřice influent and effluent was performed.
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Study of biocompatible polymers degradation
Oborná, Jana ; Márová, Ivana (referee) ; Vávrová, Milada (advisor)
This bachelor thesis is focused on biocompatible polymers degradation study. Both poly(D,L-lactic-co-glycolic acid)-g-polyethyleneglycol-g-poly(D,L-lactic-co-glycolic acid) copolymers and their forms modified with itaconic acid were monitored. This work verified the optimal analytical procedure for monitoring the degradation of investigated copolymers. Bio-degradation of polymers occured at 37 °C in phosphate buffer with pH=7.4. High performance liquid chromatography with UV-VIS detection of diode-array type was used for determation of the degradation products. Gel permeation chromatography with refractive index detector was used for the assesment of the change of molecular weight polymer chain after the degradation.
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Controlled Drug Release from Biodegradable Hydrogels.
Oborná, Jana ; Chýlková, Jaromíra (referee) ; Kráčmar, Stanislav (referee) ; Kučerík, Jiří (referee) ; Vávrová, Milada (advisor)
This dissertation is focused on the controlled release of drugs from a biodegradable amphiphilic hydrogel based on hydrophobic poly(lactic acid), poly(glycolic acid) and hydrophilic poly(ethylene glycol) (PLGA-PEG-PLGA, ABA) and its modification with itaconic anhydride (ITA). The resulting ,-itaconyl(PLGA-PEG-PLGA) copolymer is referred to as ITA/PLGA-PEG-PLGA/ITA or ITA/ABA/ITA. Itaconic acid provides reactive double bonds and a functional carboxyl group at the ends of the PLGA-PEG-PLGA copolymer chain, thereby rendering the modified ITA/ABA/ITA copolymer less hydrophobic and offering the possibility of forming a carrier for hydrophilic drug substances. These functional copolymers are thermosensitive and change in the external environment (e.g. temperature) causes a sol-gel phase transition due to the formation of micellar structure. The bioactive substances can thus be mixed with a copolymer which is in a low viscous phase (sol phase) and subsequently the mixture can be injected into patient's body at the target site where it forms a gel at 37 °C. This hydrogel becomes a drug depot, which gradually releases the active substance. Prediction of the substance’s release profile from the hydrogel is an effective tool to determine the frequency of administration, potentially enhancing efficacy, and assessment of side effects associated with dosing. The analgesic paracetamol and the sulfonamide antibiotic sulfathiazole were used as model drugs, representing hydrophilic and hydrophobic substances, respectively. The active substances had a significant effect on the resulting hydrogel stiffness. Type of solvent, incubation medium and nanohydroxyapatite also influenced on the gel stiffness and subsequent stability of the hydrogel-drug system. Controlled release of drugs took place in simulated conditions of the human body. Verification of Korsmeyer-Peppas (KP) drug-release model is also discussed in this thesis. The KP model was found suitable for simulating the release of sulfathiazole from ABA and ITA/ABA/ITA hydrogels. On the contrary, the performance of KP model was not suitable for describing the release of paracetamol from the ABA hydrogels. Therefore, a new regression model suitable for both buffered simulated media and water has been proposed. The proposed model fitted better the release of both sulfathiazole and paracetamol from composite material prepared from ABA hydrogel and nanohydroxyapatite.
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|
|
Study of degradation of biocompatible copolymers
Oborná, Jana ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
This diploma thesis is focused on biocompatible polymers degradation study. Copolymers were studied based on poly(lactic-co-glycolic) acid and poly(ethylene glycol) PLGA-PEG-PLGA and further these copolymers modified with itaconic acid ITA-PLGA-PEG-PLGA-ITA. This paper investigated the influence of pH phosphate solution on the degradation of polymers. Degradation of polymers occurred at 37 °C in phosphate solution with pH 4.2, 7.4 and 9.2. High performance liquid chromatography with UV-VIS detection of diode-array type was used for quantitative determination of lactic acid and glycolic acid as the final degradation products. For qualitative identification of additional degradation products were used tandem connection liquid chromatography and mass spectrometry. Gel permeation chromatography with refractive index detector was used to determine the molecular weight decrease polymer chain after the degradation.
|
|
|
The issue of penicillin antibiotics in water
Landová, Pavlína ; Oborná, Jana (referee) ; Vávrová, Milada (advisor)
This bachelor thesis deals with the occurrence and determination of penicillin antibiotics in wastewater. Penicillin V was selected as a representative of this class of antibiotics due to its frequent prescribing. Solid phase extraction (SPE) was selected as a method of isolation of the analyte from the wastewater. Optimal conditions were found for Bakerbond C18 SPE column. Drug analysis was carried out on ultra-high performance liquid chromatography (UHPLC) with diode array detection (UV-VIS/DAD). Under optimized conditions, the analysis of wastewater from the WWTP Brno Modřice influent and effluent was performed.
|
|
|
Study of biocompatible polymers degradation
Oborná, Jana ; Márová, Ivana (referee) ; Vávrová, Milada (advisor)
This bachelor thesis is focused on biocompatible polymers degradation study. Both poly(D,L-lactic-co-glycolic acid)-g-polyethyleneglycol-g-poly(D,L-lactic-co-glycolic acid) copolymers and their forms modified with itaconic acid were monitored. This work verified the optimal analytical procedure for monitoring the degradation of investigated copolymers. Bio-degradation of polymers occured at 37 °C in phosphate buffer with pH=7.4. High performance liquid chromatography with UV-VIS detection of diode-array type was used for determation of the degradation products. Gel permeation chromatography with refractive index detector was used for the assesment of the change of molecular weight polymer chain after the degradation.
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