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Spectroscopic Study of Singlet Oxygen in Cells and Model Systems
Scholz, Marek ; Dědic, Roman (advisor) ; Heřman, Petr (referee) ; Kubát, Pavel (referee)
Title: Spectroscopic Study of Singlet Oxygen in Cells and Model Systems Author: Marek Scholz Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. Roman Dědic, Ph.D., KChFO Abstract: Singlet oxygen (1O2), the first excited state of molecular oxygen, plays many important roles in nature and technology. The work is aimed at development of novel methods for monitoring of 1O2 in cells and other biological samples. Two main ap- proaches were employed: direct detection of the very weak near-infrared phospho- rescence of 1O2, and detection of Singlet Oxygen-Feedback Delayed Fluorescence (SOFDF), which is the emission from the photosensitizer induced by energy transfer from 1O2. The first part of the thesis introduces the basic concepts of photophysics and photochemistry of 1O2: its generation, deactivation, applications, and overview of detection methods. The second part presents the experimental results. Wide-field mi- crospectroscopic detection of 1O2 phosphorescence enabled us to acquire 1O2-based images and near-infrared spectra from single cells incubated with photosensitizers. However, the direct detection suffers from the inherently very low phosphorescence quantum yield. It is shown that SOFDF may overcome this problem and become a promising alternative tool for studies of 1O2 and...
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Time-Resolved Fluorescence of Protoporphyrin IX
Kozáková, Veronika ; Dědic, Roman (advisor) ; Fučíková, Anna (referee)
Title: Time-Resolved Fluorescence of Protoporphyrin IX Author: Veronika Kozáková Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. Roman Dědic, Ph.D., Department of Chemical Physics and Optics Abstract: The bachelor thesis deals with concentration dependence of endogeneous photosensitizer Protoporphyrin IX fluorescence lifetimes in model solutions in THF and DMSO using time-correlated single photon counting technique. Protoporphyrin IX represents a photosensitizer utilized in photodynamic therapy and photodiagnosis of oncologic and other chronic diseases. It is naturally occuring precursor in biosynthesis of heme in cells. Biologically relevant concentration ranges of Protoporphyrin IX were investigated. Increasing lifetimes with increasing concetrations of Protoporphyrin IX were found both in THF and in DMSO. The increase from 8.85 ns to 9.22 ns in the former is under 3% experimental uncertainty. The increase from 9.96 ns to 12.29 ns is well over the uncertainty in the case of DMSO. Keywords: fluorescence, TCSPC, Protoporphyrin IX
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Fluorescence Detection of Skin Tumours
Stíbal, Adam ; Dědic, Roman (advisor) ; Hála, Jan (referee)
This thesis discusses the photodynamic therapy (PDT) and it's application for dia- gnostics of tumours. The PDT is based on production of reactive oxygen species (ROS) from the molecules of photosensitizers (PS). PS are preferentially accumulated in disea- sed tissues, where ROS are produced and cause selective destruction of the target tissue, while surrounding healthy tissue remains intact. The photodynamic diagnostics uses the fluorescence of PS for digital and spectral imaging. This thesis is focused on detection of tumours from spectral characteristics of protoporphyrin IX fluorescence induced in tis- sue by methyl-aminolevulinate. The main part of the research was realised on rats' scars in vivo, the solutions of homogenized mouse fibroblasts were also studied. The way to distinguish between diseased and healthy tissue was found using measurements of fluo- rescence bleaching kinetics.
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Methods of Study of Photosensitizer-Photophysics with Application on Thiazolyl-porphyrins
Scholz, Marek ; Dědic, Roman (advisor) ; Hála, Jan (referee)
Title: Methods of Study of Photosensitizer-photophysics with Application on Thiazolyl-porphyrins Author: Marek Scholz Department: Department of Chemical Physics and Optics Supervisor: RNDr. Roman Dědic, Ph.D. Supervisor's e-mail address: Roman.Dedic@mff.cuni.cz Abstract: Photodynamic therapy for oncologic and various chronic diseases is a rapidly emerging method of treatment. It is based on the production of highly reactive singlet oxygen and free radicals by excitation energy transfer from the molecules of photosensitizers. Photosensitizers are preferentially accumulated in the target tissues and locally illuminated. This way produced reactive species cause apoptosis or necrosis of the cells leading to the desired therapeutic effect. Synthesis and subsequent photophysical characterization of photosensitizing dyes is a fundamental part of the development of photodynamic methods. The main aim of the work is to explain the most widely used methods of photophysical study of photosensitizers and apply them to new synthesized photosensitizers: thiazolyl-porphyrins. Methods of absorption and fluorescence spectroscopy, flash- photolysis, time- and spectral-resolved detection of luminescence, optoacoustic spectroscopy and other spectroscopic methods were used. Thiazolyl-porphyrins proved to be promising new...
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Vliv redoxního stavu na zhášení excitace v bakteriochlorofylových agregátech
Paleček, David ; Dědic, Roman (advisor) ; Polívka, Tomáš (referee)
Harvesting only 4 % of light striking the Earth could possibly fulfill present energy demands of a mankind. Chlorosome of green sulfur bacteria is re- garded as suitable light-harvesting system for photosynthesis imitation. This work presents comparison of absorption and hole burning spectra of artificially prepared aggregates similar to chlorosomes with different compositions in order to verify the proposed role of quinones in excitation quenching and its redox de- pendence. Absorption spectra at room and helium temperature showed a resem- blance between artificial aggregates and chlorosomes. Hole burning experiments verified the role of quinones in excitation quenching under aerobic conditions. Even more pronounced excitation quenching was observed under anaerobic con- ditions. Significant improvements of the original experimental set-up provided better experimental data which raised many further question that are worth trying to answer in the future.
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In situ Luminescence Detection of Singlet Oxygen
Vyklický, Vojtěch ; Dědic, Roman (advisor) ; Mojzeš, Peter (referee)
The thesis summarises already published results of singlet oxygen luminiscence detection in relation to photodynamic therapy treatment. The spectroscopic and photosensitising properties of the photosensitizer TMPyP and their comparison with already published properties of TPPS4 are presented. Also the inuence of phosphatidylcholine on photosensitising properties of TPP and singlet oxygen lifetime was investigated. The thesis is mainly focused on adaptation and optimisation of experimental setup for singlet oxygen luminescence deteciton from the surface of solid samples with time and spectral resolution using optical fibres with luminescence probe. The usability was tested on polymer matrix (PMMA or polystyrene) containing protoporphyrine IX. Finally, the kinetics of singlet oxygen phosphorescence measured from surface of thin layer of 3T3 murine fibroblasts containing TPPS4 or TMPyP are presented. Thereby the feasibility of singlet oxygen detection in situ was demonstrated using this setup.
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Information Strategy
Kratochvíl, Tomáš ; Dědič, Roman (referee) ; Koch, Miloš (advisor)
This diploma thesis is focused on the possibility of using modern approaches to information technology management. Specifically, it concentrates on demands for innovation of software development lifecycle management. The theoretical part of the thesis is focused on methods used in information strategy. Based on results of the analytical part, where I evaluate current approach to information technologies service management, I suggest solutions in the form of customer oriented information strategy and approach to the management of software development as a part of service lifecycle.
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