This diploma thesis summarizes knowledge from the fields of synthesis, characterization and application of titanium dioxide nanotubes and its combination with silver nanoparticles for biomedical purposes. Basic protocols of working with cell cultures and bacteria are also included. Experimental part of this diploma thesis focuses mainly on the synthesis of tubular structures made of titanium dioxide via anodic oxidation of 500nm titanium layer and their subsequent decoration with silver by electrodeposition. Last section of the experimental part is devoted to testing of antibacterial properties of the new material and examining the effect of different silver concentrations on the adhesion of MG-63 cells. All results are compared to reference samples consisting of titanium dioxide nanotubes without silver.

This thesis is focused on nanoparticles produced by internal combustion engines utilized in vehicles. It deals with spatial distribution of nanoparticles within urban areas, impact of alternative fuels usage on particle production and toxicity, and a particle toxicological testing methodology. Monitoring of airborne nanoparticles identified traffic as the main source of airborne nanoparticles in places with heavy traffic load (Prague), as well as in a small city with only local traffic (Čelákovice). Most particles were likely emitted during short episodes of high emissions (e.g. uphill acceleration). During the measurements, high-emission vehicles responsible for a large fraction of the air pollution were also identified. On the other hand, small non-road internal combustion engines, which are not subject to any limit on particle emissions, such as a lawn mower, were operated during the measurement and generated a large number of nanoparticles. The amount and characteristics of the particles produced by combustion depend on the combustion technology and the fuel composition. A large part of the thesis deals with alternative fuels and their effects on the quantity of produced particles and toxicity of organic matter adsorbed on the particles. Hydrotreated vegetable oil (HVO) exhibited the lowest...

Nano-structured materials are widely applied for various applications like photovoltaics, electrochromics and sensors. A challenging task in all these fields is the functionalization of these materials with a molecule of interest for the desired application. This work demonstrate the post grafting of the most important and commonly used nano-structured material, mesoporous TiO2, with different bifunctional molecular linkers. These compounds basically have two functional groups, the phosphonic acid group which coordinates to the TiO2 surface and a positive and negative head group which controls the surface charge and the potential interaction of the surface with species in solution. These two groups are systematically separated by alkyl group of different chain length which controls the hydrophobicity of the surface. It is shown that the new surface modification technique simplifies the molecular requirements for functional surface modifiers considerably. Using a limited set of organic anchors with adjustable head group charge and hydrophobicity, broad range of molecules can be adsorbed onto TiO2. Different applications based on such modified surfaces were explored and demonstrated. The modified surfaces can be used to incorporate different charged guest molecules, electrochromophores and dyes which enable to probe their electrochemistry and photovoltaic properties on the surface. Supra-molecular self assembly inside the modified pores is possible which can be monitored by different methods. The study includes the prepartaion of the modified surfaces and their characterization using different electrochemical methods, FTIR spectroscopy, Quartz Crystal Microbalance, Contact angle and Scanning Electron Microscopy measurements.

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Táto práca sa zaoberá technikou výroby samousporiadaných nanoštruktúr pre elektrické aplikácie. Prototypy boli pripravené anodickou oxidáciou v dvoch dĺžkach a tromi rôznymi tepelnými úpravami. Štrukturálna charakterizácia bola spravená pomocou techniky SEM, TEM a EDX a vyhodnotenie nielen z štrukturálneho, ale aj z materiálového hľadiska. Jedinečná koreňová štruktúra samousporiadaných nanotyčiniek bola vyhodnotená a porovnaná po troch rôznych tepelných úpravách: po anodizácii, po vákuovom žíhaní, a po žíhaní vo vzduchu. Všetky prototypy obsahujú nanotyčinky s amorfnou štruktúrou, ale našli sa však aj nanokryštály pod koreňovými štruktúrami. Elektrická charakterizácia prototypov ukázala: odporové spínacie správanie (RS), diódové charakteristiky a charakteristiku podobnú pre diódy s kapacitorom. Aktívny povrch pre spínací mechanizmus je v hornej časti nanoštruktúr na rozhraní nanotyčiniek a zlatej elektródy. Výška Schottkyho bariéry na rozhraní Ti / TiO2 bola vypočítaná dvoma spôsobmi a pre všetky tri zariadenia bola nižšia ako 1,11 eV.

Nanomaterials have attracted substantial attention in the area of catalysis due to the unique properties they exhibit such as high surface areas, intricate pore networks and unique morphologies. TiO2 has attracted attention as a catalyst since the discovery of its high photocatalytic activity by Fuishima and Honda in 1972. Given its high thermal stability, low cost, low environmental impact, and versatility, TiO2 is a widely used commercial catalyst and catalyst support. TiO2 is used in many applications such as photocatalysis is also an excellent support material for noble metals in a number of oxidative synthesis and pollution-control reactions. Though TiO2 is a widely used catalyst support, currently available commercial titanias often have low surface area and poor thermal and hydrothermal stability. While several methods reported in literature produce materials of higher surface area and more ideal porosity relative to commercially available titanias, these procedures generally involve inherent drawbacks including time-consuming, complicated, and expensive processes that are not industrially viable. Cost-effective, large-scale preparations of stable, high surface area, mesoporous TiO2 need to be developed. The work in this dissertation focuses on (1) producing high surface area stabilized TiO2 supports of controlled pore diameters and (2) the preparation of well dispersed Pt on these supports using industrially viable processes. The effects of dopants Al, La, Si, and Zr on the stability, surface area, and porosity of anatase TiO2 supports were investigated. Results show that dopants increased the surface area and thermal stability of anatase through structural modifications and grain growth inhibition. Stabilized titanias produced by this method demonstrated equivalent or higher thermal stability and surface area compared with pure anatase and previously reported materials after treatment at 400°C and 700°C including 22 mol% Al-TiO2 calcined at 400°C which had a surface area of 479 ± 39 m2/g, a pore volume of 0.46 ± 0.04 cm3/g, and a pore diameter of 2.9 ± 0.2 nm. Ten synthesis variables were examined and optimized using statistically designed experiments (DOEs). Equations were developed to predict the conditions to obtain the highest surface area and pore volume at the desired pore diameter and predict the pore diameter range that may be obtained for aluminum-modified anatase TiO2. Confirmation trials closely matched predicted surface areas, pore volumes, and pore diameters in all but one trial, demonstrating the power of DOEs in identifying and controlling synthesis variables in relatively few experiments. The structure of Al-modified anatase TiO2 was analyzed to determine the mechanism of Al stabilization. Surface Al stabilized TiO2 by lowering anatase surface energy, stabilizing planes of high surface energy which would otherwise join to achieve stabilization. Al in TiO2 lattice vacancies stabilized TiO2 through increasing lattice strain and limiting mass transport necessary for grain growth. Results demonstrate the importance of structure analysis of doped nanomaterials in the development of stabilized catalysts and catalyst supports. An industrially viable, one-pot synthesis of Pt supported on 22 mol% Al-modified anatase is presented. Pt dispersions as high as 54% (one-pot method) and 59% (DI method) have been obtained. Results show that this one-pot method and the DI method using our Al-modified supports are promising syntheses of highly dispersed Pt catalysts and demonstrate that the alumina-stabilized anatase support is superior to other many available anatase supports.

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