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The D-A and pi-pi interactions and their use in self-assembly
Rejchrtová, Blanka ; Starý, Ivo (advisor) ; Kotora, Martin (referee)
The D-A and π-π Interactions and Their Use in Self-Assembly Due to their well-defined shape, size and properties gold nanoparticles represent an advantageous platform for the study of non-covalent interactions between ligands anchored to their surface both in solution and in monolayers or thin films. The aim of this thesis was the synthesis of ligands for gold nanoparticles bearing an anchoring group at one end and a planar π-electron rich pyrene unit at the other. Six structurally variable ligands were prepared differing in the pyrene substitution pattern and the spacer between the aromatic part and the acetylated thiol function. Furthermore, a synthetic pathway leading to extended π-electron systems (both electron rich and electron poor) such as hexabenzocoronene derivatives and its fragments was explored. The key steps in the synthesis of these compounds are the cyclization reactions of alkynes leading to polycyclic intermediates and their ensuing cyclodehydrogenation (Scholl reaction). All of the prepared ligands and their intermediates were characterized by spectroscopic methods. The structure of the key hexakis(pentafluorosulfanyl-phenyl)benzene was confirmed by single crystal X-ray crystallography. The prepared ligands bearing a pyrene unit were deacetylated and anchored to the surface of...
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Gold nanoparticles as a tool of targeted therapy of cancer
Knoblochová, Lucie ; Hodný, Zdeněk (advisor) ; Brábek, Jan (referee)
Nanomaterials have caught the interest of biomedical science because of their size (which enables them to interact with cellular structures), high surface area, and unique physical properties. Gold nanoparticles (GNPs) can be synthesised in various shapes. Their common property is surface plasmon resonance, which makes it possible to detect these particles with high resolution using dark field microscopy. GNPs can be efficiently modified with various ligands such as drugs, antibodies, or aptamers; this can be utilized to selectively bind GNPs to tissues, e.g. for drug delivery. Conjugated GNPs can also be used in diagnostics of tumor cells as well. Photothermal therapy consists of GNPs selectively binding to the tumor tissue, where they transform light into heat upon irradiation by near-infrared (NIR) light, thereby damaging nearby cells. The toxicity of GNPs is currently unclear. Research into modified gold nanoparticles is of great interest for targeted tumor therapy, as it may yield a tool for the selective destruction of tumor cells.
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Preparation of plasmonic nanoparticles in non-aqueous environments and in water using chemical way and by laser ablation and their testing
Hochmann, Lukáš ; Šmejkal, Petr (advisor) ; Procházka, Marek (referee)
Příprava nanočástic (N) se stala význačnou oblastí chemie díky unikátním vlastnostem, které tyto částice mají a které vedou k širokému okruhu možných aplikací. N se běžně používají v katalýze, elektronice, fotonice a nachází se i v mnoha předmětech běžné denní potřeby. Navíc, vzhledem ke svým plasmonickým vlastnostem, se N ušlechtilých kov· hojně používají ve spektroskopii, kupříkladu při povrchově zesíleném Ramanově rozptylu (SERS). V závislosti na plánovaném použití N lze k jejich přípravě použít více cest. V pří- padě přípravy N v kapalinách (koloid·) lze použít r·zné metody chemické redukce. Tyto metody jsou dobře zavedené postupy, obzvláště ve vodném prostředí. Pro určité aplikace by však byly příhodnější koloidy v jiných rozpouštědlech. Proto je hlavním cílem této práce zhodnotit možnosti přípravy koloid· chemickou redukcí a laserovou ablací ve vodě a organick- ých rozpouštědlech. Dalším cílem je charakterizace připravených částic a zhodnocení jejich potenciálu pro SERS. Zlaté koloidy ve vodě a alkoholech byly připraveny redukcí kyseliny tetracholoro zlatité tetrahydridoboritanem sodným. K přípravě stabilních sol· v alkoholech byl dále nutný pří- davek polyvinylpyrrolidonu (PVP) jako stabilizátoru, protože přímá příprava koloid· chemickou redukcí v alkoholech vedla k jejich kolapsu. Dále...
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Plasmonically active electrochemical electrodes based on tungsten disulfide nanotubes decorated with gold nanoparticles
Salajková, Zita ; Daňhel,, Aleš (referee) ; Ligmajer, Filip (advisor)
When an electromagnetic wave illuminates metal nanostructure under right circumstances, it can couple to the motion of electrons and thus give rise to so-called LSPR. When these collective oscillations non-radiatively decay, they excite charge carriers that can have, for a short moment of time, highly non-thermal energy distribution. These so-called "hot" electrons and holes can then take part in photochemical applications, e.g. in reactions on photoactive electrodes where hot electrons act as catalysts. Gold nanoparticles seem to be a good candidate for fabrication of such electrodes because they exhibit resonantly enhanced absorption due to plasmon excitation in the visible and near infrared spectral range, which could make the solar energy harvesting more efficient. In this work we present electrohemical experiments that should help to clarify the underlying principles of photochemical reactions involving hot electrons. Our model system consists of indium tin oxide electrodes covered with tungsten disulphide nanotubes that were previously decorated by gold nanoparticles. By comparing the results of chronoamperometric measurements on individual components of this system it was shown that excitation of plasmonic nanoparticles indeed leads to photocurrents and that electrochemical methods can serve as a valuable tool for analysis of photochemical reactions catalyzed by hot electrons.
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Photoelectrochemical properties of titanium dioxide doped by metals
Vičarová, Monika ; Drbohlavová, Jana (referee) ; Dzik, Petr (advisor)
This thesis deals with the optimization of materials and processes for making layers of titanium dioxide enriched with metal nanostructured aggregates. These layers have a plasmonic effect in visible light radiation. Gold-doped titanium dioxide thin films were applied to the FTO glass substrate by spin-coating method and calcined at 450 ° C for 30 minutes. Two forms of titanium dioxide and two different gold precursors were used to make the layers. The structure of the layers was observed by optical and SEM microscopy. The photoelectrochemical properties of the prepared layers were studied by electroanalytical methods linear sweep voltammetry and chronoamperometry.
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Analysis of one-dimensional structures using Kelvin Probe Force Microscopy
Kovařík, Martin ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This bachelor's thesis deals with the use of Kelvin probe force microscopy (KPFM) for analysis of 1D nanostructures, namely germanium nanowires and tungsten disulfide (WS2) nanotubes. First part of this thesis is dedicated to the possibility of gold nanoparticles detection on germanium nanowires and also to the analysis of relevance of the KPFM method to measurements performed at various humidity. Second part deals with the measurement of surface potential changes on WS2 nanotubes induced by interaction with light. We have concluded, that relative surface potential changes can be measured at various humidity. This conclusion is also applied to study the interaction of WS2 nanotubes with monochromatic light. The experiment has revealed, that when exposed to light with defined wavelength, nanotubes coated with gold nanoparticles show opposite surface-potential changes as compared to pristine nanotubes, which indicates different physical processes under way.
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The Introduction of Contact Ecotoxicity Tests for the Assessment of Terrestrial Ecosystems
Modlitbová, Pavlína ; Kráčmar, Stanislav (referee) ; Beklová, Miroslava (referee) ; Demnerová, Kateřina (referee) ; Vávrová, Milada (advisor)
This dissertation thesis is focus on using toxicity tests with testing organism - terrestrial isopod Porcellio scaber. This organism is use for toxicity assessment of selected anorganic compunds which could contaminate terrestrial ecosystem. This organism was selected for several reasons - sophisticated test methodology; well known biology of these animals and their ecological relevance. Besides classical endpoints such as mortality, change in mass of test specimens and the effect of the presence and concentration of contaminants onto food consumption; we monitored changes in the morphometric characteristics at the level of tissues and cells, the cytotoxicity and possibly bioaccumulation in various parts of the body of the organism. Selected test substance in this thesis were nanoparticles and inorganic salts. Wherein for chosen gold nanoparticles was carried out a complete study presents several levels of organization of living matter (organism, tissue, cell). For selected salts compound, this study was carried out on the behavior of organisms and classical endpoints.
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Analysis of Nanostructures by ToF-LEIS
Duda, Radek ; Král, Jaroslav (referee) ; Mašek, Karel (referee) ; Dub, Petr (advisor)
The presented thesis deals with the utilization of TOF-LEIS analytical method in the area of nanostructure analysis. A new procedure for depth profiling of the elemental composition of the sample, based on the alternate measurement with the DSIMS method, was established. The TOF-LEIS method is able to detect the interface between the layers before its mixing by the ion beam of the DSIMS method. Furthermore, a procedure of TOF-LEIS spektra modification was established to obtain the actual concentration of elements in the sample by reduction of a multiple collision contribution. By comparison of TOF-LEIS spectra with the results received by the DSIMS method the ratio of molybdenum and silicon ion yields was obtained. In the next section advantages of the TOF-LEIS method in combination with XPS during analysis of thermal stability of gold nanoparticles are presented. The mutual complementarity of both methods is shown and final conclusions are supported by electron microscopy images. The final section deals with a newly assembled apparatus for the TOF-SARS analytical method and shows its possibilities regarding the detection of hydrogen on the graphene.
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Characterization of semiconducting nanowires
Novotný, Karel ; Grym, Jan (referee) ; Kolíbal, Miroslav (advisor)
This diploma thesis is focused on characterization of semiconductive nanowires. Theoretical part of thesis deals with basic physical properties of TiO2 and a search of selected properties of titanium dioxide nanostructures is preseted. The experimental part describes several spectroscopic measurements carried out with complex of TiO2 nanowires. The influence of gold nanoparticles (deposited on the nanowire surface) on sample properties is also tested. The final part of thesis is devoted to methodology for measurement of electrical properties. These experiments are carried out only with one nanowire. Focused electron beam induced deposition (resp. Focused ion beam induced deposition) and electron lithography are utilized.
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