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Effect of bioceramic additives on morphology, physical and biological properties of collagen scaffolds for bone tissue engineering
Klieštiková, Nikola ; Poláček, Petr (oponent) ; Brtníková, Jana (vedoucí práce)
The diploma thesis deals with preparation of three-dimensional porous collagen composite scaffolds for bone tissue engineering and study of the effect of addition of bioceramic particles on morphological, biomechanical and biological properties. Theoretical part describes biomaterials and bioceramic particles used for scaffolds in bone tissue engineering and their fabrications method. As for experimental part, samples were prepared by the freeze-drying method. As tested material, type I collagen from porcine and bovine sources was combined with hydroxyapatite and mixture of -tricalcium phosphate and -tricalcium phosphate in ratios 1 : 1, 1 : 2 and 2 : 1. The effect of bioceramics solubility and particle sizes on scaffolds morphology, biomechanics and biocompatibility was evaluated. Addition of bioceramic particles changed the morphology of the samples. The pore size decreased, whereas the porosity was nearly the same in all tested samples. Bioceramic particles also made the collagen matrix of the scaffolds less hydrophilic, moreover they stabilized the scaffolds against the effect of enzymatic degradation. The biomechanical properties of the samples were tested in both dry and hydrated state. In dry state, the pure bovine collagen scaffolds reached the highest compressive strength, contrary in hydrated state, the samples containing bioceramic particles reached the highest value. None of the samples was cytotoxic and the most preferable environment for cell adhesion and proliferation was in the pure bovine collagen scaffolds and also in the composite scaffolds with ratio HAp : -TCP : 1 : 1.
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Rheological properties of biodegradable thermosensitive copolymers
Chamradová, Ivana ; Poláček, Petr (oponent) ; Vojtová, Lucy (vedoucí práce)
The general goal of the proposed diploma work was preparation, characterization and rheological study of well-defined “smart” injectable hydrogels from biodegradable, biocompatible, controlled life-time copolymers based on hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(lactic acid)—co—poly(glycolic acid) (PLA/PGA) copolymer. Resulted thermosensitive PLGA—PEG—PLGA copolymer, which gels at body temperature, was additionally functionalized by itaconic anhydride (ITA) from renewable resources, bringing both reactive carbon double bonds and functional —COOH groups to polymer ends. Additionally, the PLGA—PEG—PLGA copolymer was modified by inorganic bioactive hydroxyapatite (HAp) for usage as injectable bone bioadhesive. Both functionalized ITA/PLGA—PEG—PLGA/ITA copolymer and PLGA—PEG—PLGA/HAp polymer composite affected rheological properties of original PLGA—PEG—PLGA copolymer deciding whether or not would be the new polymeric material suitable as injectable drug carrier or bone adhesive in medical applications. Experimental part of this thesis describes mainly characterization of viscoelastic properties of both unmodified and ITA or HAp modified PLGA—PEG—PLGA copolymer by test tube inverting method (TTIM) and dynamic rheological analysis. Advantage of TTIM is sol-gel visualization with determination of the critical gelation temperature and the critical gelation concentration. The rheological measurements provide information about viscosity and elasticity of the gel by the changes storage (G´) and loss (G´´) modulus. The prepared copolymers were additionally characterized by 1H NMR and GPC. Surface and HAp particles size was determined by both SEM and Laser Particles Size Analyzer. Both unmodified and ITA or HAp modified PLGA—PEG—PLGA copolymers exhibited sol-gel transitions induced by increasing temperature. Rheological properties of copolymers’ 6 to 24 wt% water solutions investigated either by TTIM or by rheometer were in good agreement. Evaluating by rheometer, the copolymers showed two cross-points, where G´= G´´. The first one very well corresponded with the first sol-gel transition found via TTIM. The maximum values of G´ representing the highest gel stiffness lie in the white gel observed by TTIM. The second cross-point constituted to the gel-suspension transition where white polymer is precipitated from the water. The gel stiffness grows with increasing polymer concentration in water. In comparison, ITA modification or addition of HAp (0, 10, 20, 30, 40, 50 wt%) caused increasing the gel stiffness of unmodified PLGA—PEG—PLGA copolymer and approximating the temperature of G´max closer to body temperature (37 °C). Investigated both ITA/PLGA—PEG—PLGA/ITA copolymer and PLGA—PEG—PLGA/HAp composite were proved to be suitable candidates as injectable systems for drug delivery or regenerative medicine in orthopedics or dental applications, respectively.
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Studium biokeramických materiálů na bázi fosforečnanů vápenatých
Kolář, Martin ; Maca, Karel (oponent) ; Cihlář, Jaroslav (vedoucí práce)
Byla připravena rešerše na téma „Biokeramické materiály“ se zaměřením na vrstevnaté biomateriály na bázi fosforečnanů vápenatých. Na základě získaných informací byly navrženy a provedeny experimenty přípravy vrstevnatých materiálů na bázi fosforečnanů vápenatých metodou spin-coating se zaměřením na optimalizaci podmínek nanášení vrstev. Dále byly provedeny experimenty přípravy objemové hydroxyapatitové keramiky uniaxiálním lisováním s následným tepelným zpracovaním. Připravená vrstevnatá a objemová keramika byla hodnocena z hlediska bioaktivních vlastností testováním interakcí se simulovanou tělní tekutinou.
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Syntéza biokeramických materiálů na bázi hydroxyapatitu
Kočicová, Pavla ; Králová, Marcela (oponent) ; Částková, Klára (vedoucí práce)
Práce se zabývá precipitační syntézou nanočásticového hydroxyapatitu s cílem posoudit vliv reakčních podmínek na morfologii částic. Teoretická část je zaměřena na obecnou charakterizaci biomateriálů, biokeramik a fosforečnanů. Dále se konkrétně zabývá hydroxyapatitem, jeho charakteristikou a možnými syntézami. Experimentální část práce popisuje precipitační syntézu hydroxyapatitu. Syntézy probíhaly při reakční teplotě 0-80 °C, při pH = 8-11, při době stárnutí 0-24 h, v přítomnosti povrchově aktivní látky (PAL) a chelatačního činidla a při postprecipitačním hydrotermálním nebo ultrazvukovém zpracování. K popisu připravených prášků byla využita rastrovací elektronová mikroskopie (SEM), transmisní elektronová mikroskopie (TEM), rentgenová difrakce (XRD), laserová difrakce (LD) a analýzy specifického povrchu (BET). Precipitační syntézou byly připraveny čisté prášky hydroxyapatitu nebo směs hydroxyapatitu a fosforečnanu vápenatého. Morfologie částic HA byla silně ovlivněna reakční teplotou – se zvyšováním teploty vznikaly rozměrnější částice s jasnější morfologií, většinou ve tvaru tyčinek. Na morfologii částic HA mělo značný vliv postprecipitační hydrotermální zpracování, které způsobilo vznik kulovitých nebo mírně podlouhlých částic. Reakční prostředí voda/etanol mělo vliv na morfologii částic – inhibovalo jejich růst.
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Preparation of thin wall ceramic hollow fibers by dip-coating
Gockert, Radek ; Maca, Karel (oponent) ; Salamon, David (vedoucí práce)
This master thesis deals with the production of ultrathin ceramic hollow fibers by dip-coating. Preparation of ceramic hollow fibres is nowadays limited by dimension of outer and inner diameter. Application of dip-coating for preparation of ultrathin hollow fibers is new and technologically demanding process that requires the choice of a suitable sacrificial template, while mastering the control of coating parameters. The basic materials selected with high application potential are hydroxyapatite and titanium dioxide. Self-supporting hollow fibers with wall thickness below 1 m were successfully prepared from both materials. Furthermore, dip-coating process of thin sacrificial templates was described. This method is unique because it allows the production of ultrathin ceramics fibers with an outside diameter below 100 m and a wall thickness below 1 m.
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Polymeric Materials for the Controlled Drug Delivery and Controlled Release of Active Substances
Chamradová, Ivana ; Kučerík, Jiří (oponent) ; Lehocký,, Marián (oponent) ; Vojtová, Lucy (vedoucí práce)
The literature review of proposed doctoral thesis summarizes knowledge of both present-day biomaterials and the new type of “smart” biomaterials such as thermosensitive copolymers. Among those copolymers whose aqueous solutions are liquid at laboratory temperature but turn into a solid gel as the temperature rises to 37 °C belong e.g. amphiphilic triblock copolymers based on the biodegradable hydrophobic polylactide, polyglycolide and hydrophilic poly(ethylene glycol) (PLGA PEG PLGA). Commercially available thermosensitive PLGA PEG PLGA copolymers, known as ReGel or OncoGel are used as injectable controlled drug delivery systems for diabetes or cancer treatment, respectively. However, PLGA PEG PLGA copolymers might be used as well as inorganic drug delivery carries and biodegradable implants for regenerative medicine in orthopedic and dental applications. For this reason the biocompatible hydroxyapatite (HAp), utilized in the bone remodeling process, was employed because of its majority representation in hard tissue. The experimental part of this work is focused on the preparation of HAp/PLGA PEG PLGA composites, where used HAp was in the form of either nano- (n-HAp) or core-shell (CS) particles. Novel core-shell particles, prepared by double emulsion method, were consisted of “rigid” n-HAp core covered by PLGA PEG PLGA shell additionally end-functionalized by itaconic acid (ITA/PLGA PEG PLGA/ITA). ITA modification brought crosslinkable both double bonds and functional carboxylic groups to the ends of copolymer chains. Consequently, the ITA/PLGA PEG PLGA/ITA copolymer shell was chemically crosslinked to form life-time controlled 3D polymer network surrounded HAp core resulting in crosslinked core-shell particles (CS-x). The ATR-FTIR spectroscopy proved the presence of “new” ester bonds in polymer shell at 1021 cm-1 arising from the carbodiamide coupling reaction between -OH and -COOH groups. As mentioned above, both n-HAp and CS-x particles were mixed with the copolymer thermosensitive PLGA PEG PLGA matrix and flow/gelation behavior important for injectable materials were evaluated by rheological measurement. . It was found, that the addition of less than 5 wt.% of n-HAp particles or 10 wt.% of CS-x particles into the PLGA PEG PLGA polymer matrix retains its thermosensitive properties. However, adding higher amount of either n-HAp particles or CS-x particles in copolymer matrix changed the aqueous sol to permanent stiff gel while the temperature increases above 37 °C. Based on the ICP-OES analysis, the release of CS-x particles from 10 w/v % PLGA PEG PLGA gel matrix to the incubation medium at 37 °C was faster than in case of n-HAp particles (6 % vs. 3% in 9 days, respectively) which are more strongly bonded to matrix micellar structure. As a conclusion, composite based on n-HAP particles in copolymer matrix exhibiting stiff permanent gel at body temperature is suitable more as biodegradable bone adhesive while composite consisting of CS-x particles in thermosensitive copolymer matrix is useful as injectable drug delivery carrier.
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Příprava biokeramických materiálů pro medicínské aplikace
Doboš, Petr ; Šoukal, František (oponent) ; Palou, Martin (vedoucí práce)
Cílem práce bylo připravit vzorky práškového hydroxyapatitu pomocí sol-gel a precipitační metody. Po syntéze byly prášky vylisovány a vypáleny při teplotách 500 °C, 800 °C a 1100 °C. Vzorky HAP byly podrobeny analýze FTIR, XRD, SEM. Výsledné měření poukazuje na velikost HAP částic v rozmezí mikro až nano rozměrů. Průměrná velikost dominantních zrn je v oblasti kolem 5 – 8 µm pokryté menšími částicemi o rozměru 1 µm. Byla sledována mikrostruktura materiálu a bioaktivita in vitro v simulovaném krevním roztoku po 4 týdnech. Bioaktivita byla ovlivněna teplotou výpalu, od které závisí mikrostruktura. Je zřejmé, že tloušťka vrstvy hydroxyapatitu na povrchu roste s teplotou výpalu.
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Stress-strain analysis of skull implant
Hřičiště, Michal ; Borák, Libor (oponent) ; Marcián, Petr (vedoucí práce)
Cranial implants are used as a substitute for parts of cranial bones that lost its function due to trauma or disease. An important factor, that influences function of the cranial implant structure, is its mechanical behavior. This thesis briefly summarizes current knowledge in the field of cranial defect reconstruction and provides comparison of different types of materials and implant wall shapes, based on stress-strain analysis of Computer Tomography based neurocranial model with placed implant and loaded by intracranial pressure and external load.
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Studium biokeramického kompozitu na bázi hydroxyapatitu a bioskla
Virágová, Eliška ; Hadraba, Hynek (oponent) ; Drdlík, Daniel (vedoucí práce)
Tato bakalářská práce se zabývá studiem biokeramických kompozitních materiálů na bázi hydroxyapatitu (HAp) a bioskla (BG). Pro přípravu těchto materiálů byla zvolena metoda mokrého tvarování – elektroforetická depozice (EPD). Byla evaluována metodika přípravy a její vliv na relativní hustotu a distribuci pórů v připravených kompozitech. Bylo provedeno studium slinovacího procesu připravených kompozitních materiálů pomocí vysokoteplotní dilatometrie s následným vyhodnocením mikrostrukturních a mechanických vlastností. Bylo zjištěno, že pomocí EPD lze úspěšně připravit částicové kompozity, jejichž mikrostrukturní kvalitu ovlivňuje zejména elektrická vodivost suspenze. Při studiu kinetiky depozičního procesu bylo zjištěno, že EPD probíhá nejrychleji v suspenzi s nejnižší elektrickou vodivostí. Se zvyšujícím se obsahem BG v HAp rostla relativní hustota materiálů a také docházelo ke snížení četnosti a zvětšení průměru pórů. Při vysokoteplotní dilatometrii byl patrný pokles relativního smrštění se vzrůstajícím obsahem HAp ve struktuře. Pozorování mikrostruktury ukázalo krystalickou strukturu BG a otevřenou porozitu HAp, která je pro biokompatibilní materiály žádoucí. Fázové složení jednotlivých materiálů bylo určeno pomocí rentgenové difrakční analýzy. V rámci mechanických vlastností byl zjištěn nárůst tvrdosti a Youngova modulu pružnosti se vzrůstajícím obsahem BG v biokeramických kompozitech. Na základě získaných poznatků byl identifikován vhodný postup a materiálové složení pro plánovanou přípravu funkčně gradientního materiálu na bázi HAp a BG
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Advanced preparation of inorganic (ceramic) particles and nanostructures
Šťastná, Eva ; Martinovou,, Lenku (oponent) ; Vojtová, Lucy (oponent) ; Částková, Klára (vedoucí práce)
An electrospinning process was used for bioactive nanofibrous structures preparation. Neat polycaprolactone nanofibres and polycaprolactone nanofibres containing hydroxyapatite nanoparticles were successfully prepared via electrospinning and characterized using scanning electron microscopy. Mechanical properties of the nanofibres were analyzed using uniaxial tensile strength test. Results of the testing showed strong influence of the nanofibres direction alignment and nanoparticles presence on the mechanical properties of the prepared structures. The direction alignment contributed to higher elastic modulus and failure stress regardless the presence of the hydroxyapatite nanoparticles in the structure. However, the direction alignment considerably reduced failure strain of the structure. An interesting phenomenon occurred by the composite nanofibres – the influence of the hydroxyapatite particles was more distinct by the random fibres (they worsened failure strain and failure stress of the random composite fibres) but the hydroxyapatite particles did not have such strong effect on the parallelly aligned fibres. The samples were then modified by surface low-temperature plasma treatment to improve biological properties of the nanofibres. Change of the nanofibres surface characteristics was examined by contact angle measurement by sessile drop method and by XPS spectroscopy. The contact angle measurement showed that the plasma treatment considerably increased structures hydrophilicity – was unmeasurable. The XPS analysis explained the effect of the plasma treatment on microscopical scale – the plasma treatment had affected only polymer constituent of the treated structure, the hydroxyapatite nanoparticles remained intact. Selected prepared structures were biologically tested. Test in simulated body fluid proved high bioactivity of the polycaprolactone/hydroxyapatite composite nanofibres through precipitation of calcium phosphates phases on the composite structures. Following in-vitro tests using living cell cultures (ISO 10993-5 and WST-8 test) proved beneficial influence of the hydroxyapatite in the structure and of the surface plasma treatment when bioactivity of the plasma treated composite structures increased 1.5 times compared to the neat as-spun polycaprolactone fibres.
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