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Electronic effects at the interface between biomolecules, cells and diamond
Krátká, Marie ; Rezek, Bohuslav (advisor) ; Cifra, Michal (referee) ; Skládal, Petr (referee)
Understanding and control of interactions between biological environment (cells, proteins, tissues, membranes, electrolytes, etc.) and solid-state surfaces is fundamental for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and implant materials as well as for environmental monitoring, security and other fields. Diamond can provide unique combination of semiconducting, chemical, optical, biocompatible and other properties for this purpose. In this thesis we characterize electronic properties of protein-diamond interface by employing a solution-gated field-effect transistor (SGFET) based on hydrogen-terminated diamond, surface of which is exposed to biological media. We elucidate the role of adsorbed protein layer on the electronic response of the diamond transistor. We investigate effects of cells (using mainly osteoblast cells as model) on diamond SGFETs transfer characteristics and gate currents. We employ nanocrystalline diamond (NCD) thin films of different grain sizes (80 - 250 nm) to characterize and discuss influence of grain boundaries and sp2 phase on bio- electronic function of SGFETs. We investigate effects of gamma irradiation on function and stability of hydrogen-terminated diamond SGFETs interfaced with proteins and cells, showing feasibility of...
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Superconductivity in disordered systems
Šopík, Břetislav ; Lipavský, Pavel (advisor) ; Novotný, Tomáš (referee) ; Munzar, Dominik (referee)
Author: Mgr. Břetislav Šopík Thesis advisor: doc. Pavel Lipavský, CSc. Ph.D. thesis Superconductivity in disordered systems Abstract We study some aspects of the superconductivity in disordered systems - namely the superconductivity in a boron-doped diamond. We also apply theoretical methods originally developed in the field of the disordered systems to the theory of superconductivity. In the case of the boron-doped diamond we focus on the question of the dependence of the critical temperature Tc on boron doping. We discuss the impact of the boron distribution correlations on the Tc as well. First, we evaluate the density of states at the Fermi energy N0 within the dynamical cluster approximation. We discuss the Tc as a function of N0 within the BCS, the McMillan and the Belitz theory. In the case of 100 samples, the simplified Belitz theory gives the best agreement with experimental data. For 111 samples the McMillan theory is sufficient. We also show that the difference of 100 and 111 samples in the N0 dependence of Tc can be explained as given by attractive correlations in the boron distribution. Applying the concept of the coherent potential approximation, we re- move a self-interaction from the Galitskii-Feynman T-matrix approxima- tion. This correction has no effect in the normal state but makes the...
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Dynamics of modified diamond nanocrystals in living cells
Majer, Jan ; Libusová, Lenka (advisor) ; Fišer, Radovan (referee)
Nanodiamonds (NDs) are an interesting platform in biological applications and disease treatment. Because of their photoluminescence properties and modifiable surface, they have been investigated as potential carriers for drugs and nucleic acids as well as fluorescent probes. In order to design NDs meeting specifically desired parameters, which would succeed in clinical trials and in medicinal therapy, understanding the mechanism of uptake and intracellular fate of NDs is crucial. The diploma thesis is focused on mechanistic investigation of ND-based nanoparticles delivering nucleic acids to human cells. First, NDs coated with a novel cationic co-polymer were prepared. NDs were then complexed with siRNA in order to transfect siRNA inside U-2 OS cells. NDs proved to be biocompatible and effective transfection particles as observed by qPCR and colorimetric cytotoxicity and cell viability tests. To examine ND uptake by cells, we inhibited endocytosis by specific inhibitors. Obtained results implicated that ND uptake was clathrin- and caveolin dependent. Nonetheless, more than half of NDs was internalized by cells in a different fashion. Some NDs colocalized with early endosomes, lysosomes and caveolin-derived endosomes after internalization. Other NDs resided either in unknown cell structures or escaped from...
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Laser spectroscopy of crystalline and nanocrystalline diamond
Zukerstein, Martin ; Trojánek, František (advisor)
The aim of this thesis is a study of NV centres in crystalline and nanocrystalline diamond by laser spectroscopy methods. In the theoretical part we discuss the laser spectroscopy methods, the studied material - diamond and the NV colour centres. In the experimental part we discuss the influence of nanoparticle size on luminescence spectra. We measure the luminescence of samples at room and also at low temperatures depending on the intensity and wavelength of the excitation. We study the photo-conversion of negatively charged state of NV centres to the neutral in detail. We make the time resolved measurements of the luminescence on streak camera for characterization the dynamical properties of the studied samples. The result is the comparison of lifetimes of the states in NV centres in selected samples.
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Design and synthesis of surface architectures on fluorescent nanodiamonds
Havlík, Jan
anks to their unique properties and high biocompatibilities, fluorescent nanodiamonds are promising representatives of modern carbon nanomaterials with a broad range of applications. Nevertheless, their wider use is limited because of weak fluorescence intensity and low colloidal stability in the biological environment. e optimization of treatment procedures and development of new suitable surface designs is therefore critically needed. In this study, several key steps for fluorescent nanodiamond treatment have been optimized, leading to both a substantial increase in fluorescence intensity and to significantly lower surface damage caused by graphitization. Further, a new high-throughput irradiation technique was developed. e influence of surface chemistry on the fluorescence parameters was studied using partial fluorination of the functional groups on the nanodiamond surface. A novel method which significantly affects the interaction of nanodiamonds with biological systems by increasing of the homogeneity and circularity was developed. e potential of nanodiamonds for future medical and biological research was demonstrated on particles with complex surface architectures that enabled targeting and therapy of tumor cells. Moreover, a strong and highly selective affinity of fibroblast growth factors to diamond...
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Ultrafast highly nonlinear processes in diamond
Zukerstein, Martin ; Trojánek, František (advisor) ; Kloz, Miroslav (referee) ; Kužel, Petr (referee)
Intense few-cycle laser pulses can significantly affect the properties of transparent solids during the interaction. These processes take place on femtosecond time scales and they can be studied using ultrafast spectroscopic methods. This dissertation deals with highly nonlinear processes in diamond. In the interaction with a crystalline diamond, we observed a strong nonlinear broadening of the spectrum due to self-phase modulation effect, which allowed us to create a simple technique for compression of pulses from laser oscillator. At the same time, strongly nonlinear five-photon absorption was observed, in which we found a significant anisotropy and dependence on the polarization state. With two-beam pump and probe experiments we present a study of anharmonic phenomena in the dynamics of coherent phonons in diamond, additionally we created a new detection technique of lattice vibrations using multiphoton absorption. Finally, the high time resolution of the experiments revealed that the sub-picosecond electron dynamics strongly depends on the composition and morphology of the polycrystalline diamond thin films. The experimental results of this work provide comprehensive research into the interaction of diamond with few-cycle laser pulses and the development of new spectroscopic methods.
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Spectroscopy of semiconductors with ultra-high time resolution
Hanák, Martin ; Trojánek, František (advisor) ; Kozák, Martin (referee)
This thesis is aimed at building and optimization of a new experiment setup for measuring time-resolved transmittance using a pump-probe method. Test measurements were then conducted on a sample of SiV centers in diamond. The theoretical part contains a general description of luminescence of color centers. It then specifically focuses on SiV centers in diamond and describes their structure, electronic and spectral properties in detail. The description of our setup and its optimization is given at the beginning of the experimental part. The dependencies of differential transmittance of SiV centers in diamond on excitation intensity and wavelength were measured and the lifetime of SiV centers was then determined from our measurement results. 1
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Dynamics of modified diamond nanocrystals in living cells
Majer, Jan ; Libusová, Lenka (advisor) ; Fišer, Radovan (referee)
Nanodiamonds (NDs) are an interesting platform in biological applications and disease treatment. Because of their photoluminescence properties and modifiable surface, they have been investigated as potential carriers for drugs and nucleic acids as well as fluorescent probes. In order to design NDs meeting specifically desired parameters, which would succeed in clinical trials and in medicinal therapy, understanding the mechanism of uptake and intracellular fate of NDs is crucial. The diploma thesis is focused on mechanistic investigation of ND-based nanoparticles delivering nucleic acids to human cells. First, NDs coated with a novel cationic co-polymer were prepared. NDs were then complexed with siRNA in order to transfect siRNA inside U-2 OS cells. NDs proved to be biocompatible and effective transfection particles as observed by qPCR and colorimetric cytotoxicity and cell viability tests. To examine ND uptake by cells, we inhibited endocytosis by specific inhibitors. Obtained results implicated that ND uptake was clathrin- and caveolin dependent. Nonetheless, more than half of NDs was internalized by cells in a different fashion. Some NDs colocalized with early endosomes, lysosomes and caveolin-derived endosomes after internalization. Other NDs resided either in unknown cell structures or escaped from...
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Design and synthesis of surface architectures on fluorescent nanodiamonds
Havlík, Jan
anks to their unique properties and high biocompatibilities, fluorescent nanodiamonds are promising representatives of modern carbon nanomaterials with a broad range of applications. Nevertheless, their wider use is limited because of weak fluorescence intensity and low colloidal stability in the biological environment. e optimization of treatment procedures and development of new suitable surface designs is therefore critically needed. In this study, several key steps for fluorescent nanodiamond treatment have been optimized, leading to both a substantial increase in fluorescence intensity and to significantly lower surface damage caused by graphitization. Further, a new high-throughput irradiation technique was developed. e influence of surface chemistry on the fluorescence parameters was studied using partial fluorination of the functional groups on the nanodiamond surface. A novel method which significantly affects the interaction of nanodiamonds with biological systems by increasing of the homogeneity and circularity was developed. e potential of nanodiamonds for future medical and biological research was demonstrated on particles with complex surface architectures that enabled targeting and therapy of tumor cells. Moreover, a strong and highly selective affinity of fibroblast growth factors to diamond...
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Electronic effects at the interface between biomolecules, cells and diamond
Krátká, Marie ; Rezek, Bohuslav (advisor) ; Cifra, Michal (referee) ; Skládal, Petr (referee)
Understanding and control of interactions between biological environment (cells, proteins, tissues, membranes, electrolytes, etc.) and solid-state surfaces is fundamental for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and implant materials as well as for environmental monitoring, security and other fields. Diamond can provide unique combination of semiconducting, chemical, optical, biocompatible and other properties for this purpose. In this thesis we characterize electronic properties of protein-diamond interface by employing a solution-gated field-effect transistor (SGFET) based on hydrogen-terminated diamond, surface of which is exposed to biological media. We elucidate the role of adsorbed protein layer on the electronic response of the diamond transistor. We investigate effects of cells (using mainly osteoblast cells as model) on diamond SGFETs transfer characteristics and gate currents. We employ nanocrystalline diamond (NCD) thin films of different grain sizes (80 - 250 nm) to characterize and discuss influence of grain boundaries and sp2 phase on bio- electronic function of SGFETs. We investigate effects of gamma irradiation on function and stability of hydrogen-terminated diamond SGFETs interfaced with proteins and cells, showing feasibility of...
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