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Preparation and application of nanoparticles and nanofibres with natural UV filters
Plachá, Monika ; Skoumalová, Petra (referee) ; Márová, Ivana (advisor)
The presented diploma thesis is focused on preparation of nanoparticles and nanofibres with natural UV filters. Liposomes with encapsulated aqueous, ethanol and lipid extracts were prepared. Nanofibers from PHB containing lipid extract were prepared too. As a part of this work, an overview of natural sources with potential effects as UV filters were introduced. Moreover, nanoparticles and nanofibers and methods of their characterization were described. Size, polydisperse index and colloid stability of prepared nanoparticles were characterized via DLS. In experimental part aqueous, ethanol and lipid extracts were prepared from roasted coffee, green coffee and cascara. These extracts were spectrophotometrically characterized for the content of polyphenols, flavonoids, antioxidant activity, tannins and their SPF. Liposomes and liposomes containing PHB with these extracts were prepared and the encapsulation effectivity, short–term and long–term stability as well as SPF of nanoparticles were determined. Nanofibers from PHB containing lipid extracts were prepared via electrospinning and forcespinning methods. Prepared nanofibers were examined via FTIR–ATR. Antioxidant activity, short–term and long–term stability were determined spectrophotometrically. From selected nanoparticles, emulsions and gels were prepared and their SPF was also determined. Three types of emulsions with the best SPF were selected and tested on volunteers. Sedimentation stability of emulsions was tested by analytical centrifuge. Finally, cytotoxicity of selected nanoparticles and nanofibers was tested via MTT assay using human keratinocytes.
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Study of preparation and structure of nanofibers of inorganic and organic biomaterials
Ručková, Jana ; Částková,, Klára (referee) ; Cihlář, Jaroslav (advisor)
The aim of this Master’s thesis is to investigate the preparation and structure of nanofibres of inorganic and organic biomaterials. Nanofibres of polycaprolactone, chitosane and their composites with hydroxyapatite particle were prepared by centrifugal force spinning process, which uses centrifugal forces for nanofibres spinning. Designed nanofibres can be used in bone tissue engineering. Experimental activity has started with synthesis of hydroxyapatite nanoparticles and preparation of polymer solutions and composite suspensions at different concentrations. The solutions and the suspensions were characterized by density and viscosity which were changed in dependence on temperature and polymer concentration. The solutions and the suspensions were spun at varying speeds and using two different sizes of collectors. The dependence of spinneret head revolution speed, size of collectors and polymer concentration on nanofibres diameter was studied. Biological activity of polycaprolactone and hydroxyapatite/polycaprolactone nanofibres was tested by means of SBF.
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PREPARATION AND APPLICATION OF SOME BIOPOLYMERS, NANOPARTICLES AND NANOFIBRES FOR COSMETICS AND FOOD
Bokrová, Jitka ; Pekař, Miloslav (referee) ; Kráčmar, Stanislav (referee) ; Márová, Ivana (advisor)
The presented doctoral thesis is focused on preparation of nanoparticles and nanofibers with natural active ingredient and testing their biological effects. Modern types of application forms were prepared from biomaterials based on one or more natural polymers. Chitosan particles were prepared from cross-linked polymer using ultrasonication. A mixture of soy lecithin and cholesterol was used for preparation of liposomes. Poly-3-hydroxybutyrate was used for preparation of combined liposomes, too. All liposome particles were prepared by ultrasonication. Nanofibers were obtained from polyhydroxybutyrate using electrospinning. Mixtures of low-molecular antioxidants obtained by extraction from natural sources were used as active ingredients. Different types of teas, barks, herbs, spices, fruits and vegetables were selected as sources of natural antioxidants. Total phenolic and flavonoid content and total antioxidant activity of extracts were determined using spectrophotometrical methods. Obtained natural extracts were subsequently used for encapsulation. Prepared application forms were characterized in terms of their physicochemical properties. Particle size was monitored by dynamic light scattering. Colloidal stability of particles in suspension was determined using zeta potential. Spectrophotometry was used to evaluate the efficiency of encapsulation of active compounds into particles. The morphology of the new type of combined PHB liposomes was monitored by electron microscopy. Chromatography was used for quantification of individual components of particles. Morphology of nanofibers and incorporation of active agent into their structure were monitored using FTIR-ATR spectroscopy and electron microscopy. Afterwards, antimicrobial, cytotoxic and genotoxic effects of preparations were evaluated. It was found that the most suitable types of extracts for liposome preparation are aqueous and lipid extracts of natural antioxidants. Prepared particles showed excellent stability and good encapsulation efficiency. The study confirmed that incorporation of polydroxybutyrate into liposome structure does not reduce neither the colloidal stability of the particle, nor the efficiency of encapsulation process. Antimicrobial and antimycotic effect of preparations against model microorganisms Micrococcus lutues, Serratia marcescens and Candida glabrata was detected. It was found that process of encapsulation increases the inhibitory effect of natural extracts of antioxidants. The safety of preparations was assessed using two human cell cultures: epidermal keratinocytes and HaCaT cell line. Assays of cell viability and plasma membrane integrity were used to determine cytotoxicity of preparations. Low toxicity of liposome particles was confirmed by a series of cytotoxic tests. Obtained data showed that association of phospholipid with PHB polymer does not cause a significant increase in cytotoxicity in human skin cells. Genotoxicity testing on model procaryotic organism confirmed zero genotoxic potential of preparations. The new type of combined particles and polymeric fibers cant thus be used as a carrier for active ingredients, complex natural extracts, antimicrobial agents and many others.
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Utilization of Nanofibres in the Traditional Ceramics Body
Sedláček, Daniel ; Stančík,, Hynek (referee) ; Sokolář, Radomír (advisor)
This thesis summarizes the current knowledge about ceramic composites with nanofibers. So far, most research focused on the reinforcement of hi-tech ceramics, such as carbides and nitrides, however, this traditional ceramics left behind. Due to the improving the efficiency of production of nanofibers and thus a drop in prices, companies consider their use even in a cheaper ceramic materials. Reinforcement of traditional ceramic shard could theoretically improve many characteristics, but there are absolute minimum of practical researches.
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Preparation and characterization of nanostructured resorbable substitutes for accelerated skin healing
Kacvinská, Katarína ; Muchová, Johana (referee) ; Vojtová, Lucy (advisor)
Spolu s narastajúcimi nárokmi na kvalitu liečby v oblasti popálenin a plastickej chirurgie existuje možnosť ako uplatniť nové technologické riešenie na liečbu porúch s celkovou stratou kožnej vrstvy. Diplomová práca sa zaoberá prípravou nanoštrukturovaného, dvojvrstvového skafoldu pre využitie v tkánivovom inžinierstve, ktorý nahrádza kožnú časť dermis (dolná porézna vrstva) a bazálnu membránu (horná a tenká nanovlákenná vrstva). Zákaldom dolnej pórovitej vrstvy je kolagén, charakterizovaný v prítomnosti ďalších polysacharidových aditív: chitosan, vápenatá soľ oxidovanej celulózy (CaOC), sodná soľ karboxymetylcelulózy (NaCMC). Zároveň prídavok dopamínu a fibroblastového rastového faktoru (FGF), s cieľom zlepšiť biomechanické vlastnosti, regulovať a podporovať hojenie kože. Tenká nanovlákenná vrstva je zložená zo želatíny, polycaprolaktónu (PCL) a CaOC. Sú navrhnuté dva rôzne mechnizmy prípravy skafoldu, ktoré sa odlišujú sa v prítomnosti sieťovaných a nesieťovaných nanovláken. Skafoldy boli charakterizované z hľadiska biomechanických, štruktúrnych vlastností a in vitro. Vrchná nanovlákenná vrstva poskytuje mechanickú podporu, ktorá je výrazne zvýšená prítomnosťou polydopamínu (PDA). Test botnania poréznej vrstvy skafoldu ukázal na dostatočne veľké póry, umožňujúce filtráciu buniek. Táto botnatosť bola znížená v prítomnosti PDA, ktorý má zároveň významný vplyv na časové predĺženie degrádácie v prítomnosti kolagenázy a lyzozýmu. Spolu s FGF výrazne podporil proliferizáciu a životaschopnosť myších fibroblastov. Nanoštrukturovaný, dvojvrstvový skafold má potenciál pre budúce aplikácie pri hojení rán, kedže sa vyznačuje dobrými mechanickými vlastnosťami a umožňuje bunkám adherovať, proliferovať a formovať extra celulárny matrix.
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Investigation of nanomaterials for their nuclear power and research utilization
Jelínek, Martin ; ČEZ,, Jiří Skalička, (referee) ; Katovský, Karel (advisor)
This bachelor thesis provides a comprehensive overview of the properties of various nanomaterials and summarizes the latest findings and knowledge of advanced applications in all sectors of nuclear power engineering from construction materials through nuclear fuel, fuel cladding, neutron moderator and coolant to the advanced methods for detection of ionizing radiation ad its direct utilization for electricity production. A significant space is devoted to the applications in safety systems of nuclear power plants. The experimental part of the thesis deals with the possibility of using carbon nanofibers as an additive to the coolant in VVER reactor type in order to improve the thermal properties of the coolant. So far a very little examined issues of neutron balance changes due to interaction with nanoparticles was experimentally verified on the paraffin wax mixture of two different concentrations. The comparison with the reference sample of pure paraffin was also made.
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Preparation and optimization of electrospun materials suitable as electricity generators
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This master's thesis is focused on energy harvesting and is divided into two parts: theoretical and practical part. The theoretical part of the thesis contains the dielectric parameters, the meaning of the piezoelectric and triboelectric effect and the principles of electric energy gain in energy havesting. The last chapter of the theoretical part is devoted to various electrospun materials suitable for energy harvesting. The practical part of the work deals with nanofibers as an energy generator and describes their dielectric parameters. In this part the relative permittivity and loss factor of selected types of nanofibers are measured. Also the triboelectric nanogenerator is made and it's properties are measured.
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The Effect of Nanofibres Dispergation on the Properties of Sintered Ceramic Body
Němec, Tomáš ; Keršner, Štěpán (referee) ; Sokolář, Radomír (advisor)
The main goal of this diploma´s thesis is to review final qualities of traditional porcelain body with using nanofibers. The theoretical part of the thesis summarizes the current knowledge of the research on ceramic composite with using nanofibers. The vast majority of these researches is engaged by reinforcing technical ceramics, on the other hand area of traditional porcelain is still unexplored area. Besides that there are shown technological ways of the production and dispersion of the most important types of nanofibers. In the practical part of this thesis is experimentaly defined the most effecient way of homogenization procedure and the most effecient dose of nanofibers for pure kaolin body. In conclusion are compared the resulting properties of traditional porcelain body with using Al2O3 and SiO2 nanofibers.
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Hyaluronan nanofibers
Linhartová, Beáta ; Velebný, Vladimír (referee) ; Pekař, Miloslav (advisor)
This bachelor´s thesis deals with the most common methods of producing nanofibres, it presents an overview of these techniques and briefly desribes common models. It shows their advantages and disadvantages and tries to follow the develompent of nanofibres. This theoretical part is followed by an experimental one which describes concrete example of producing nanofibres.
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